141

CHISELS. - BY HENRY FOWLER, Member, CHIEF MECHANICALENGINEER, MIDLANDRAILWAY, DERBY.

Very considerable attention has been given to the composition and treatment of tool-steel used in machine-tools, but the three implements of the hand worker-the file, the chisel, and the hammer-have been comparatively neglected. The Author is aware of the work recently done in testing the former of these, and knows that there is little need of improvement with the last- named, but believes that the chisel has not received the systematic attention its importance deserves. A close examination of the new and used chisels in the shop, over which he had control, confirmed that view, and the result was an effort to induce the Alloys Research Committee of the Institution to take up the matter. For various reasons this was not successful, and so the matter has been dealt with individually. The material usually employed for chisels is not bought to specification, but a well-known and tried brand is purchased. In the Chief Mechanical Engineer’s Department of the Midland Railway, after considerable experiment it was decided to order chisel steel to the following specifications :-‘‘ Carbon 0 * 75 per cent. to 0 85 per cent., the other constituents being normal.” This gives a complete analysis as follows :- [THE I.MEcH.E.] L

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FIG.1.-Heavy Brass Work. FIG.6.--Dimond Point fw Jagging, etc.

I

FIG.%-Heavy Iro+&aid Steel Castings. FIG.7.-Lolzg ~TOSSCut.

FIG. 3.-Cylinder Repairs. (Right Hand.) FIG.a.--Round Nose, *--4

L-L-----J -9.’----4 3,

FIG.4.-Side Tool. (Right Hand.) FIG.9.-Gouge Tool.

(J -1.O”A

FIG.B,-Squnre Arose. FIG.10.-White Metal. kll-4

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Per cent. Carbon . . . . . 0.754.85 Manganese . . . . 0.30 Silicon . . . . 0.10 Sulphur . . . . 0.025 Phosphorus . . . . 0.025

It is perhaps interesting to note that the analysis of a chisel which had given excellent service was as follows :- Per cent. Carbon . . . . . 0.75 Manganese . . . . 0.38 Silicon . . . . . 0.16 Sulphur . . . . 0.028 Phosphorus . . . . 0.026 The heat treatment this chisel received is unknown. At the same time that chisel steel was standardized, the form of tbe chisels themselves was revised, and a standard chart of these as used in the locomotive shops was drawn up. Figs. 1 to 10 show the most important forms of these tools, which are made to stock orders in the smithy and forwarded to the heat-treatment room where the hardening and tempering are carried out on batches of fifty. A standard system of treatment is employed here which to a very large extent does away with the personal element. Since the chemical composition is more or less constant, the chief variant is the section which causes the temperatures to be varied slightly. The chisels are carefully heated in a gas-fwed furnace to a temperature of from 730"-740" C. (1346"-1364" F.) according to section. In practice the chisel, Fig. 1, is heated to 730" C., chisel, Fig. 2, to 735" C. (1355' F,), and a 1-inch half round chisel to 740" C., because of their varying increasing thickness of section at the points. Upon attaining this steady temperature, the chisels are quenched to a depth of Q inch to 4 inch from the point in water, and then the whole chisel immersed and cooled off in a tank containing linseed oil. This oil-tank is cooled by being immersed in a cold-water tank through which water is constantly circulated. After this treatment, the chisels have a dead hard point and a tough or sorbitic shaft. They are then tempered or the point L2

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" let down." This is done by immersing them in another oil-bath which has been raised to about 215" C. (419" F.). The first result is of course to drop the temperature of the oil, which is gi-adually raised to its initial point. On approaching this temperature the chisels are taken out about every 2" C. rise and tested with R file, and at a point between 215" C. and 230" C. (428' F.) it is found that the desired temper has been reached, the chisels are removed, cleaned in sawdust, and allowed to cool in an iron tray. A question which naturally will be asked is whether comparative tests of these chisels with those bought and treated by the old rule- of-thumb methods have been made. It must be admitted that the Author knows of no method of carrying out such tests mechanically, other than that of hardness by the Brinell or Scleroscope method, whilst any ordinary test depends so largely upon the dexterity of the operator. The universal opinion of foremen and those using the chisels of the advantages of the ones receiving the standard treatment set out has, however, convinced the Author of the improvement made. The Author is aware that questions may be raised as to why the chisels have not been normalized at about 900" C. (1652" F.) after forging and before hardening. This matter had attention when the question was first dealt with, but at that time there were no facilities for carrying out this work. These have since been provided in connexion with certain other work, but although various chisels have been normalized in the manner mentioned, no advantage has been found in carrying this out.

The Paper is illustrated by 10 Figs. in the letterpress.

Mr. HENRYFOWLER, after reading the Paper, said he thought he ought to apologize for presenting such a short communication to the Institution, but the President might remember that his predecessor in the Chair, Sir H. Frederick Donaldson, was very anxious that the experience which engineers had gained in various

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 PSK. 1916. CHISELS. 145 parts of the country should be placed at the disposal of the whole of the members of the Institution. The first suggestion he (the Author) made was that his Paper should simply be put in the Library, in order that it might be consulted by anyone interested in the subject, but Sir Frederick Donaldson thought that it dealt with a question on which a discussion might usefully take place, The Paper was written two years ago, but his experience since had not caused him in any way to modify the treatment which his Company gave to chisels in those days. He had felt for a long time that, in spite of the very large increase of mechanical work which did away with hand-work and the use of chisels, in the advanced knowledge which was obtainable at the present day with regard to heat treatment of steel it was a pity that something more should not be done in the way of improving the position of a tool which was used so extensively by fitters. It was simply with that object in view that he had put forward the few notes contained in the Paper, trusting that it would lead to a useful discussion and perhaps a criticism of points which, although he might not be able to answer them satisfactorily, would at the same time be of interest to the members.

Discussion in Londoa.

The PRESIDENTsaid he had pleasure in moving that a very hearty vote of thanks be accorded to the Author for his exceedingly useful and interesting Paper, the more so because the members knew how busilyengaged he was on Government work, and they therefore appreciated his kindness in coming forward at the present juncture.

The Resolution of Thanks was then put and carried with tmdamation.

Sir ROBERTA. HADFIELD(Member of Cound), in opening the discussion, said that he had not paid very special attention to the

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 146 CHISELS, FEB.1916. (Sir Robert A. Hadfield.) subject of chisels beyond studying the composition of various steels and alloys for work of that kind. Not long ago he had an interesting experience in Ceylon, in connexion with ancient chisels dating back to a period early in the Christian era, and which he saw when visiting .the Colombo Museum. The then Director, Dr. A. Willey, F.R.S., was good enough to allow him to have one of them, and he had written a Paper on the subject for another Institution.* At the time it was a puzzle to him to know how the Sinhalese, who apparently had but little technical knowledge, obtained chisels of the necessary hardness for cutting purposes. The analysis showed that the material was practically pure iron so far as the shaft portion was concerned. Evidently it must have been known how to produce a chisel with hardened point, otherwise it would no& have been possible to make wrought-iron accomplish the desired work. The explanation WRS probably that the art of cementation must then have been known. In other words, the Sinhalese native took wrought-iron, embedding it in a hot charcoal fire, and'was thus no doubt able to get a certain amount of carbon absorbed by the point of the chisel, which after quenching would give a cutting edge. It was interesting to know that the Author, Mr. Fowler, was evidently an advocate and defender of their old friend carbon-steel. He had made most careful tests and, as a result, of his long experience, put forward the plain carbon-steel, containing no special element, as the best chisel that he was able to find. Personally, he (Sir Robert Hadfield) thought that, by a little further research, improved practice might be obtained by the use of an alloy steel. Members knew how important it was that a chisel should last as long and do as much work as possible. No doubt a chisel made of special steel could be produced, and that this would do more work than the steel now used. It was quite probable, therefore, that if a small Committee of the Institution were formed for this and similar purposes, further improvement in practice could be effected. For example, he suggested that if steel containing a

~ ._____.-----___---__ * Iron and Steel Institute, 1912.

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 YEB. 1916. CHISELS. 147 similar amount of carbon to that shown by the Author’s analysis were used, and to this was added about 1 per cent. of chromium-in other words, a chromium-carbon steel-a chisel would no doubt be obtained able to do more work, and thus prove of great advantage to large engineering shops. On matters of this bind he thought that if we all worked together a little more, the engineer co-operating with the chemist and the metallurgist, great improvements could be effected. A chisel might at first seem not a very important tool, but when the amount of work done by chisels in large shops employing thousands of workmen was borne in mind, there was no doubt that great economy would result by paying attention to small details. As an illustration of what he meant with regard to this suggestion of special steel, he would add that a comparatively inferior amount of work could only be got out of a projectile made of carbon-steel, and required to pierce an armour-plate. Of course, he admitted that a chisel and projectile did not have to do exactly the same kind of work, but nevertheless both had to cut or break into metal under pressure. In the case of the projectile, it was absolutely necessary to employ an alloy steel-that is, carbon- steel was not good enough for the purpose. If, therefore, a series of tests were carried out as he suggested, he felt sure considerable improvement in practice would follow. Captain Sankey reminded him that a projectile was simply a one-blow chisel, and he quite agreed with that view, although it was a very heavy blow, especially when it was borne in mind that a modern large calibre projectile struck the armour with an energy of 40,000 foot-tons or more, passing through plates 15 inches thick in l,iG part of a second. That was a very rapid one blow ! The Author stated that he took a chisel, quenched it in water, and then the whole chisel was afterwards immersed in linseed oil. He would like to ask how long the chisel was kept in the water, also about what was the temperature of the extreme point when the chisel was immersed in the oil. He supposed it would be practically cold, and therefore that the heat remaining in the chisel body might run up to the chisel-point, and slightly temper the metal in the point. If a small

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 148 CIIISELS. FSB. 1916. (Sir Eobert A. Hadfield.) Committee, such as he suggested, were formed to carry out experiments generally on this subject, as no doubt valuable results would be obtained, he hoped that they would be kept for the benefit of members of the Institution. He was glad to notice at the end of the Paper that no advantage was found in normalizing the steel for the chisels in the mitnner mentioned. In a small bar of that kind he did not think normalizing was likely to add much to the uniformity. In making chisel steel, great care was taken that only the purest materials were used, as would be seen from the analysis given, only 0.028 per cent. sulphur and 0.026 per cent. phosphorus being present. He presumed the steel was crucible steel.

Mr. FOWLERreplied in the affirmative.

Sir ROBERTHADFIELD, continuing, said the melting was very carefully carried out in crucibles, the ingot produced was passed through a minute examination by being ‘‘ topped ” and afterwards forged. Consequently a particularly uniform quality of steel was obtained, and for that reason probably normalizing would not be necessary. It was satisfactory to find that such excellent results had been obtained by the Author, who stated that fifty chisels were treated at a time. This showed the advantage of carrying out works practice methodically, and not preparing each chisel separately. Mr. Fowler was exceedingly busy at the present time, doing his utmost to help forward the munitions problem-in fact, there was no man working harder in the country. He had had many opportunities of observing the Author’s work in the last twelve months, and only on the previons Sunday had the pleasure of showing him round one of their new shops at Sheffield, 50 that the members would appreciate that they could not even respect the Sabbath in the north at present. Although the Paper was short, it was at the same time a model one, and it was possible for the members to get definite information without having too many other points for consideration placed before them. Personally, he offered his best thanks to the Author for his interesting Paper,

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 FISB. 1916. CHISELS. 149 which he would send round to all the foremen in his works, because he felt sure that they would benefit from the useful and interesting information there set forth.

Mr. DANIEL.ADAMSONasked whether the Author had been able to trace any connexion between the Scleroscope and Brine11 tests and the duty obtained from the chisels afterwards. A Committee of Engineers in Manchester was endeavouring to ascertain at the present time some connexion between such tests and the results obtained from high-speed steel turning tools. The Author also stated in the Paper that when the tools were being tempered they were tested with a file. He would be glad if the Author would elaborate his description of that process, because he was sure it would be of great value to the members.

Mr. WILLIAMH. ALLEN(Vice-president) suggested that no matter how much machinery might be improved, the first instrument which was used by man would still be wanted. Following the lead of Mr. Fowler, much work had been carried out at Bedford in constructing their various tools in a scientific way. He found the Paper extremely difficult to discuss, but he had prepared a communication showing the difference between the practice at Derby and that at Bedford, and if it were added to the discussion he thought it would prove very serviceable.

Mr. LOUGENAN PENDREDthought it would be of interest if the Author would state whether the chisels to which he referred were all hand-chisels, or whether they were also used in pneumatic tools. It used to be the practice, when he served in the shops, for the smith to harden the chisel according to the work on which it was to be used, and under those circumstances it was possible that a chisel which was suitably hardened for hand-chipping would not be suitably hardened for use with a pneumatic tool.

Mr. DRUITTHALPIN said the Author stated (page 144) that he was not aware of any comparative mechanical means that could be used

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 150 CHIBELS. FER.1916. (Mr. Druitt Halpin.) for really testing accurately what the chisels were doing. He did not know whether it had ever struck Mr. Fowler that it might be possible to use either an ordinary file-cutting machine, or some modification of it, where there was a fairly constant blow, and where the nature of the work done was the nearest approach that could be imagined to chipping.

Mr. A. W. MARSHALLthought the idea at the basis of the Paper was excellent, but it had the effect of separating the work done by the smith in forging from the hardening and tempering process. If the smith carried out the whole process, he knew to some extent how to modify or to adjust his tempering to what he had done with the chisel when he had put it in the fire for forging it, and although the systematized process of hardening and tempering might go very well by itself, there was still the uncertainty which might come in, due to the treatment the steel received by the different smiths who did the forging. He would like the Author to say how he treated the chisels after they had been used in the shops and were sent back blunted to be re-dressed. The chisel then had a certain amount of rough usage, hammering, and so on, and it had to be softened and re-forged. To what extent did that affect the systematized process of hardening Z Had the Author found it necessary to also standardize the system of softening or treating the chisels when they came back to be re-dressed Z

Mr. THOMAST. HEATONasked whether it was necessary to take any special steps to ensure that the quality of steel that was used was always exactly the same.

Mr. J. ELLESBROWN said the Suthor gave in the Paper certain lengths and sizes for the tapering-off of the chisels, but those sizes varied a.ccording to the usage. He would like to know how the angles for the tools were arrived at.

Mr. 0. T. GILLESPYsaid that no particulars were given in the

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Paper of the nature of the facets at the end of the tool, which was a matter of great importance in chipping different materials. The angles to which the chisels were forged were given for various materials, but the nature of the angles to which they were ground at the end was also very important, in his experience, in chipping such different materials as cast-iron, steel, or brass. No indication was given in the Paper as to the nature of that angle.

Mr. A. B. JACKSONinquired what the attitude of the workmen was towards the tools in question. Engineers brought out very often what they thought were theoretical improvements, but it was found that the men did not take them up. In fact, in some cases he had heard it hinted that the end was broken off and the tool re-forged by the workmen in the ordinary way. Had the Author any experience as to how the men actually treated those tools 1

Mr. DAVIDE. ROBERTScongratulated the Author on his excellent Paper and also on the good discussion it had evoked. The members in the Cardiff district hoped to have the privilege of re-discussing it at Cardiff in the following week, when he believed many of the practical people in South Wales would give the Institution the benefit of their views upon it.

Mr. GEORaE GENTRYinquired whether in quenching-off in the first case the chisel was moved from about 4 inch depth to -$ inch by the ordinary method used by a smith to prevent a sharp line of demarcation between the dead hard portion and the otherwise still hot portion. It appeared to him that probably the secret of the Author’s success was due to the fact that the chisels were let down twice. The fact of their being immersed in oil with a hot shaft would have the effect, it seemed to him, of letting down the point somewhat in the first oil-bath. Then they were let down again by being raised to the temper temperature in the second oil-bath. He would very much like to know the comparison between the ordinary temper colour for a chisel for crucible cast-steel, which he believed

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 153 CHISELS. Y&B. 1916. (Mr. George Gentry.) was somewhere about whet would be called a very dark straw, with patches of purple in it, and t,he temperature given in the Paper as the temperature of the second oil-bath, namely, 419" F. to 428" F. He asked whether it was anywhere approaching that temperature, either above or below it. (It was actually about 500" F.) The question of the best kind of oil to use was important, as it was found thnt engineer's m:Lchine-oil would not check reoalescence sufficiently in steel of so low IL carbon content as 0.75 per cent. Further reference showed that the lowest usual temper heat was not reached in the second oil-bath. Pale yellow and clear blue ranged from 430" F. to 570" F. The highest given in the Paper was 428" F.

Mr. JOHN~)EWILAXCE (Member of Council) said he was disappointed that nobody had taken up the point Sir Robert Hadfield had raised in regard to the quality of the steel, because it seemed to him that a chisel should be one of the best means of testing tool-steel. Of course, it had not the temperature to withstand that a turning tool had, because he did not suppose my workman chipped fast enough to make the point of the chisel red-hot. But at the same time, in other respects it had practically the same duty to perform as a cutting tool. It would be of great interest if any of the members could furnish information on the subject of whether high-speed steel or other improved forms of bteel had been used for making chisels. He had heard of people who had used for chisels practically the material that Sir Robert Hadfield had mentioned, namely, very mild steel, the point being hardened with prussiate of potash. The theory held was that in that way a keener cutting chisel was obtained than it was posslble to get by tempering carbon steel, because there was a very thin edge at the point of the chisel which was dead hard, supported by the soft steel hehind. He believed that was done occasionally for pneumatic tools, but he did riot know whether any of the members had any experience in thnt direction. He had not studied the subject very closely, but it would no doubt be of the greatest interest if it was possible to find what was the best steel to employ for making chisels.

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Mr. W. S. LOCKHARTasked how the chisels were served out from the store. He presumed they were served out as forgings, and the men ground them to the shape they required for the work they had to do. Under those circumstances the point arose as to the thickness of the chisel, because whether a chisel had to do heavy work or light work depended on its thickness. It was useless to attempt to do heavy work with a light chisel. He would therefore like to know whether the men were allowed to shape the tools up or to grind them down, or what was the usual practice. He did not know whether the point he desired to raise really entered into the discussion, but he would like to know if the constituents of the steel would be the same for such tools as miners’ drills, which were practically the same as a long chisel. It would be interesting to learn if the same quality of steel would serve for that purpose. It had been stated earlier in the discussion that a projectile was a single-blow chisel. It seemed to him, however, that a shell was more like a blow of a pickaxe than a chisel, and it would be interesting to know if the same quality of steel would be used for a pickaxe. Some time ago he came across an interesting point in connexion with high-speed cutting steel. He understood that some sixty years ago, when wolfram was considered worse than useless, the old smiths in Cornwall used to get a small-quantity of wolfram from the mines, smash it down on thelanvil with a hammer, and throw it into the eye of the fire when they were hardening picks, thus case- hardening them. That was practically Sheffield practice at the present day. He had never been able to ascertain how the Cornish workmen found that out. There were several other minerals available on which experiments could be made, and he supposed they tried them all till one was found suitable. It seemed to him a very important point, because at the time wolfram not only had no value, but was the bdte noire of the miner.

Mr. GEORGEWATSON, desired to support the suggestion Sir Robert Hadfield had made that a Committee should be appointed to deal withTthe very important question of hand-tools, which

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 154 CHISELS. FEE. 1916. (Xr. George Watson.) had been rather neglected in the past, and he believed if a really good set of standards could be provided, someone would start a works for making the best quality of tools, as small works were not at present equipped for making them. A man who had to carry on his business with a small staff and without the necessary appliances would have great difficulty in making tools for himself in a proper manner. He thought it might also be borne in mind whether it would not be worth while to weld a high quality of steel for the point on to a different quality of steel for the handle. Evidently the handle could not be used after it got worn down to a certain length, and he thought it might pay in the first instance to use an expensive steel for the point, and to weld it to a less expensive steel for the handle.

Mr. HENRYFOWLER, in reply, said he was exceedingly gratified at the large number of members who had taken part in the discussion, but he was disappointed that none of the members had given the Institution the benefit of their experience. Sir Robert Hadfield had mentioned the question of the appointment of a Committee to deal with the subject. Personally he did not wish to read the Paper, nor did he wish to deal with the chisel question individually- he wanted the Institution to take up the question ; and as they did not do so, he felt it was necessary to move himself. If the Paper resulted in a small Committee being formed he felt $hat what his Company had done, even if it was not exactly in the right direction, would be productive of a large amount of good to the Institution. If only one shop took up the matter, the experience obtained dealt with only that particular shop, and he did not wish to say for one moment that the experience obtained at Derby would be repeated in the shop near by. He would be very glad indeed if not only the question of the chisel but that of the set was taken up and discussed. Sir Robert Hadfield had perhaps had as much experience as anyone in the set which was used, and if that question could be dealt with at the same time, he thought it would be of benefit to the members.

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The question that Mr. Pendred raised with regard to the pneumatic tool was undoubtedly one on which, if the members exchanged their experiences, the results would be of the greatest value to the Institution and the country as a whole. He had not tried any alloy steel, and, judging from the fact that no one had mentioned it in the course of the discussion, he presumed his experience was not unique. The length of time during which the chisel was immersed in water after the first heating up was dependent upon the section; it, was until it was thoroughly chilled. At the time of writing the Paper, he had had no experience with the Scleroscope. Since then he had used it extensively for determining the hardness of certain brass, but no attempt was made to ascertain the hardness of chisels, and it was merely mentioned in the Paper for the purpose of ascertaining whether any member had had any experience of it in arriving at the hardness of the chisel. If anything was done, he thought it must be done right up against the point, and then, for comparison, farther up by the handle, to see what was the best hardness as one came along gradually to the softer parts, so that there might not be the chance of breaking off, which was one of the troubles with all chisels. He had been away from his own business for some considerable time, and he would therefore communicate in writing his answer to the question asked by Mr. Adamson with regard to testing with the file. It was very interesting to hear that Mr. Allen had been working in the same direction. He was sorry Mr. Allen was not able od the present occasion to go farther into the details of any differences which might exist between his practice and the Author's. In reply to Mr. Pendred's question, the whole of the chisels dealt with were hand-chisels. The question Mr. Druitt Halpin raised with regard to testing by file-making might be of very considerable advantage, and if, when file-makers were less busy, they offered to lend one of their machines for the purpose, he would be glad to try it. It must be borne in mind, however, that they had to deal with various metals,

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 156 CHISELS. Pen. 1916. (Nr. Henry Fowler.) because the usual material froni wliich a file was made would not be suitable for that for which a chisel was usually employed. Mr. Marshall had asked whether the smith carried out the work. The drawing down of the chisel was done in the smithy, and then it went up in the heat-treatment room, and the repairs to the chisels were usually carried out there-that is, when the ends of the chisels were destroyed for some reason or other, the work was usually done by a smith in the room in which the heat treatment was afterwards applied. The steel was analysed for carbon as it came in, to see that it conformed with the specification, and also occasionally to see what the other constituents were, to make sure that too much phosphorus or sulphur was not obtained. He regretted that for the moment he could not state the angle of the facet, but he would supply the information later. The angles given in the Paper were those which had been determined from experience as giving the greatest degree of success in the past. At the Midland Railway Company’s works they hnd occasionally to chip broad surfaces of white metal, and Fig. 10 referred to a special chisel with a very narrow angle and R broad face which was used for that purpose. The attitude of the workmen was always a difficult matter to ascertain. If they knew that one was interested in the work, he had no doubt that, for reasons which could be readily understood, they would say it was a very fine job indeed. The workmen did nothing at all with regard to the repairs. If a man got a chisel which suited him he tried surreptitiously to get it touched up for himself, but there was no grindstone of any description in the workshop. The tools were dealt with through the store. When a man had either blunted his chisel or the point was damaged in any way, he took it to the store-that is, the small tool store, from which the tools were sent into the heat-treatment room to be dealt with afterwards, and obtained another chisel. Mr. Gentry raised a question with regard to the depth. The operator put the chisel in and moved it backwards and forwards, SO that probably the effect he spoke of tookplace through the water washing slightly up the chisel. He could not give the compnrison

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between the temper colour and the second heat. Mr. Dewrance raised an interesting point with regard to the case-hardened edge. It was not pertinent to the question of chisels, but it was a system employed with some large milling cutters, where a very large mass of steel had to be dealt with, in which the carbon was perhaps 0.4 per cent., and then the whole was case-hardened and ground up. He was very glad to find that so short a Paper had given rise to an excellent discussion, in which so many members had taken part.

The PRESIDENTsaid the members were extremely indebted to Mr. Fowler for a Paper on what was perhaps an unusual subject. The Institution generally discussed more complicated kinds of machines than those with which the Author had so lucidly dealt. Before closing the Meeting he wished to remind the members that the Annual Meeting of the Benevolent Fund would subsequently be held, and, as that was confined to members of the Benevolent Fund, it was likely to be a small one. It had therefore been suggested to him that he should say a word in the way of pleading for the Benevolent Fund before the larger Meeting concluded. The first .thing he wished to say was, that of' all times the present was one of the worst for pleading for subscriptions. All the members were asked to contribute to funds oftener than they were able to do, and the present was not a good time for asking them to increase their subscriptions to the Benevolent Fund. It was, however, a Fund in which the members were interested. It was their own Fund, which helped their own members, and towards which they ought to have a feeling of duty. The Benevolent Fund was started in the hope that it might reach to at least some $10,000 in capital value, and it had not yet reached that sum, in spite of one very large subscription which had been given. He supposed it would never grow to a very big amount until some of the members were old enough to leave legacies to it; but it was impossible to count on them, and it was the duty of the members of the Institution who could do so, without taxing themselves too much, to contribute a small subscription or annual donation. The BeDevolent Fund now Fd

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 158 BENEVOLENT FUND. FEE. 1916. (The President.) possessed a capital sum of 25,800, but only X148 was received in donations during the year towards making good what the Committee regarded as the deficiency in the amount of the Fund, and the annual income from subscriptions was only 2350. For so large an Institution he thought the smallness of those contributions was to be regretted. At the same time, he admitted that the country was passing through a period when it was difficult to plead very strongly for subscriptions. One thing had been done which might perhaps encourage some members to join the Fund, namely, the subscription for membership had been reduced from one guinea to 10s. 64in the hope that by that means a larger number of members would be obtained, because it must be remembered that membership of the Benevolent Fund carried with it some privileges. He commended the Fund to the members as one in which they ought to feel a good deal of interest.

Mr. WILLIANH. PATCHELL(Member of Council) said that before the Meeting terminated he desired to be allowed to emphasize what the President had just said in reference to the Benevolent Fund. A few weeks ago he received a letter from the widow of one of the Institution’s members asking that, as she believed he knew her late husband, he would sign the form of application to the Committee of the Benevolent Fund. Unfortunately, he had not known him, and although the member in question had a large circle of acquaintances among the members, there was not one of them who was a subscriber to the Benevolent Fund, so that his widow was quite unable, among her husband’s friends, to get the necessary signature to the application. He left it to the members to answer the question whether that was right. The Meeting then terminated.

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D~scussa'onin Cardi':

The CHAIRMAN(Mr. DAVID%. ROBERTS,Member) said he was asked by the Council of the Institution of Mechanical En,'oineers to welcome all present. Unfortunately, Mr. Fowler, the Author of the Paper, was not able to come down to Cardiff. A8 they knew, Mr. Fowler was a very busy man, being one of the chief officials at the Ministry of Munitions. The Paper was read before the Institution in London on the previous Friday, and it was felt that opportunities should be afforded to those interested in the subject in other parts of the country of expressing their views upon what was really an important practical matter. However highly developed and refined mechanical processes might become, the chisel would probably remain for many years the fitter's or mechanic's friend. As the Author remarked, while something had been done in testing the file and the hammer, there had been no systematic research with regard to the chisel. He hoped to hear useful opinions expressed and criticisms passed upon the Paper, which might help to elucidate the problem of the best treatment and analysis of the chisel. It was a subject which required and merited consideration, and he invited observations from the practical men present.

Mr. C. FARADAYPROCTOR said he regarded the hardening method described in the Paper as an old one-namely, a method which a man like himself adopted as an amateur, that is, to harden a considerable portion of the end of the chisel dead hard, and then let it down to the degree of hardness desired. But when he was an apprentice he found that the blacksmith made a considerable proportion of the chisel red hot, dipped the end into cold water, making it dead hard, and then let the heat run down from the shank of the chisel to the hardened edge. He (the speaker) thought this had some advantages; it meant that the cutting edge 1\1 2

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 160 CHISELS. Falc. 1916. (Alr. C. Faraday Proctor.) was the hardest part of the chisel, and consequently the tendency to break got less the further away from the edge. Tt also avoided any tendency to break between the clearly defined hard and soft part of the chisel which occurred in the method described by the Author; and again there was a considerable proportion of the chisel that was fairly hard, the blue coloured temper often reaching up the chisel two or three inches, For very small chisels made from 4 and $$-inch steel, he had found it advantageous to harden them throughout the whole length, and let down the shank to dark straw colour or blue, and the edge to dark straw, thus obtaining a chisel that did not bend with rough usage. He had heard blacksmiths advocate keeping the chisel out of water and hardening in oil so as to get the right degree of hardness right off. He had adopted this method for small drills in the little workshop he had at home for doing amateur work. When in France he used flat, not round or hexagonal, steel for chisels, about 4 of an inch thick, and 2 of an inch wide; it was nice to catch hold of, and he knew at once whether the edge was straight. The Author mentioned that the composition of steel was slightly altered by the process of forging; this at any rate was what he (Mr. Proctor) gathered, and it was probably so. A certain amount of carbon would be burnt out by the fire, and the more it was heated the more this would occur. If the steel was already flat, it would take less forging to make a flat chisel of it, so that there was probably less loss-assuming that this was a matter of importance-and at any rate there would be a saving of time.

Mr. THEODORESTRETTON said he was surprised to see that no mention was made in the Paper of self-hardening steels. During the latter portion of his apprenticeship he remembered very well being given chisels made up of self-hardening steel, and, to the best of his recollection, they worked very successfully. They seemed to last quite as long as chisels made up of steels which required much more careful handling, tempering, etc. The time of the man who had to make up the chisel, as well as that of the man who used it,

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 FEB. 1916. CHISELS. 161 was valuable, and it seemed to him that a considerable saving of time could be effected by the adoption of self-hardening steel. Another point which suggested itself was why the harder kinds of tool-steel, such as tungsten, or vanadium, should not be used for chisels. If there was anything against the use of such steels he would like to know what it was. A further point was, would it not be possible to devise a tool.holder for the chisel, so that higher- grade material could be used for the point, and lower-grade steel for the shank or holder. Tool-holders were used with machine-tools, and were economical.

Professor FREDERICBACON said his views lay somewhat in the same direction as the last speaker’s. The Paper said :-‘‘ After considerable experiment it was decided to order chisel-steel ” to a certain specification. What struck him about this specification was that it seemed to differ in no important particular from what would have been considered good for the purpose twenty years ago. He would imagine that a chisel that was needed to stand against manganese-steel could not be simply a carbon-steel of that kind. Perhaps the chisels which the Author had in view were to be used only on mild steel or wrought-iron, in which case the carbon-steel would answer the purpose and be cheaper than any other. Had the Author been present he would have asked for some account of the “ considerable experiment ” which led to the adoption of the specification named, and whether the experiment covered the field of special alloyed steel. One heard some strange things about self- hardening steel. He was told of a special brand which made chisels suitable for manganese-steel, but which “ turned over ” very q&kly when put on wrought-iron. The treatment described by the Author seemed well conceived. One advantage-a small one, perhaps-which he imagined was realized by having a tough or sorbitic shaft right through, was that the tail-end of the shaft would not burr over under the hammer blow in the unsightly way that it did when the shaft was quite soft. He would like to have more details of the hardening process referred to in the Paper. The treatment was carried out on

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 162 CHISELS. FYB.1916. (Professor Frederio Bacon.) batches of fifty. There could not be much delay between dipping the points in water and immersing the whole chisel in the oil, as heat spreading from the hot shafts would quickly let down the hardened points. He would like to know how that quick manipulation from the bath of cold water to the bath of cold oil was effected when dealing with these batches of fifty. The Author said he knew of no method of testing chisels mechanically; and he (Professor Bacon) was wondering whether he could not have arranged a mechanical test of a definite nature by manipulating the chisel pneumatically and automatically up to a definite depth. A concluding point he might raise was, whether it was true that a chisel on a frosty morning was apt to snap like glass as the result of the cold, or was this a superstition?

Mr. C. A. JAMESsaid that very few men in everyday workshop practice knew the constituents of the steel they were engaged on, unless some special instruction had been sent down with the steel. There were various methods of hardening steel, which accounted for some of the differences noted in the temperings. He had known spindle-steel, which had been simply cold-hammered on the anvil, do its work on sculptural or monumental stone, such as Portland stone or hard stone of that nature, and he imagined that the quality of the elements of the steel must be the cause. The Author had described how the oil-tank was cooled ; and he (Mr. James) had often wondered whether it was not advisable to have a thermometer to register at all times the temperature of the oil and of water, and as the temperature increased, to have more oil or water poured into the bath. Taps for steel-tube plates were frequently tempered in colza oil, and when rather soft, on re-heating in a greater quantity of oil, so that the cooling operation took place more rapidly, a splendid result was obtained. The process of heating should be of a slow character and thoroughly done. One of the great faults in tempering steel for chisels arose from too-rapid heating. For his own part he preferred to dip the steel altogether in water, drawing the colour down, rather than to only

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 FEB. 1916. CHISELS. 163 a depth of &inch to &inch from the point, because the line of fracture was usually to be found across the water line. He would like to ask the Author for more information about the oil-tank which was immersed in cold water.

The CHAIRMANremarked that the tempering was done in the oil-bath at 419" F.

Mr. JAMESsaid the Paper went on to describe how the chisels were taken out about every 2' C. rise and tested with a file. The operation of testing and cooling out suddenly afterwards was one that would need great care to attain the results required. He had often been struck with the fact how easy it was to get one chisel differing in temper from another, and a process that would lead to a uniform tempering would be a great boon in the engineering profession. The special treatment and special mixture of elements set out in the Paper would doubtless be followed with good results, but there were few operators in the average workshop who were acquainted with these elements.

Mr. GEORGEREEVES said he had had 27 years' experience of steel works and as a steel-user, and he considered that the analysis in the Paper was a very good one, whether for punches, dies, or chisels, or anything of that description, to be used on cold work. The analysis of steel might be excellent, but the manipulation of it for hardening and tempering needed experience, and a good workman sometimes spoilt a piece of good steel. Every one seemed to have his own particular " fad " as to the way in which he should temper steel. He himself preferred a long tempering, and not, as had been suggested, a softening right down with just the edge hard. The life of a chisel when hardened in that way could not be a long one. Immediately the edge became dull, the chisel was too soft in the back to grind again for continuous use. He believed in giving it a long purple temper, so that when the edge became blunt, it could be put on the stone and ground again. With regard to the remark of Mr. Proctor, that steel lost

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 164 CHISELS. FElL 1916. (Mr. George Reeves.) quality in re-heating, he assumed the reference was to de- carbonizing.

Mr. PROCTORremarked that it was only slightly so.

Mr. REEVESsaid it was very slight, and had very little effect upon the carbon properties of the steel. There seemed to be no standard steel for chisels. Tungsten-steel was very difficult to forge. When it was red-hot the blacksmith could knock off a piece most easily, so that it was not advantageous to choose tungsten-steel for chisels or tools to be used on cold work. Mr. James had said he would like to know what was in the Author's mind when describing his standard system of treatment, and the use of the oil-bath. The process seemed to him (Mr. Reeves) to be that the chisel was dipped and cooled off, and was then placed in a bath of oil which was already cold; and the temperature of the oil was raised to the degree mentioned, namely, 215" C. The chisel was withdrawn while the oil was being raised to this heat, and w-as tested with a file to see the effect. He saw a method practised in Yorkshire for hardening shuttle-springs, which were used in cotton factories. The spring was flat, but curled up at the end to keep down the cotton kop ; and the method adopted when heating these springs was to place a number of them in a tray, which was put in a furnace, so scientifically constructed that the exact degree of heat raised in the furnace was ascertainable. After the springs had reached a certain degree of heat, the tray was withdrawn from the furnace, and the whole of the springs were shot into a bath of whale-oil floating in a bath of water. The method of regulating the temperature was to run water constantly around this bath. After being dipped in this oil the springs, in order to be tempered, were put into a kind of oven, the temperature of which was regulated scientifically, with the aid of a FBry radiation pyrometer. Having undergone a certain degree of heat, they were again cooled off in oil. A man could then stand on tho springs and flatten them, and they would at once regain their original curve after being released from his weight.

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With regard to chisels for brass or copper cutting, it was only necessary to use a much softer steel, for it was possible to get an edge almost as hard as standard steel, which would last as long upon brass or copper as the other chisels upon iron or steel. With respect to standard steels, a speaker had spoken of them as of low-carbon for steel tool manipulation. He (Mr. Reeves) had tried cast-off spindles sold as scrap, and found a great variation in the analyses of that steel; he could make very little use of it for tools, and it had to be sold for melting again into ingots. Mr. James had spoken of a chisel made from spindle-steel which had been cold-hammered on the anvil before being used to cut stone. He would have thought that by being hammered cold, it would rupture, or become fatigued before it could be swaged out.

Mr. J. 0. DAVIESsaid attention in these days had been more especially centred upon machine-tools ; and, while for many purposes the hand-tool was antiquated, nevertheless, in the shape of the chisel, hand-punch, and cross-cut it was still a most useful article. The idea underlying the object of the Author in submitting his Paper was evidently to ascertain how the best results could be obtained from the chisel; and he (the speaker) was in hearty agreement with him. He was interested in technical education, and it was quite advantageous to youths being trained in mechanical science that they should be informed of, and be practically taught to use, all serviceable hand-tools. The Paper would do much in this direction. Like other speakers, he desired further enlightenment. For example, would they wait until a good number of chisels were ready for the gas-fired furnace before entering upon the whole process, or would they be able to use the furnace just as they needed it Z One of the speakers stated that every blacksmith had his own ‘‘ fad ” as to the method of tempering chisels. This, he thought, was rather a reflection. Any young mechanic whose ambition was to rise in his vocation would naturally try to emulate the best mechanic of his acquaintance, and, doing this, he would

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 166 CHISELS. FEB. 1916. (Mr. J. 0. Davies.) indulge in practical experiments in order to devise the best and most economical methods. These were not “ fads.” As to the dipping of the chisel in water, the character of water varied in different localities. The water of the neighbourhood in which he lived contained a considerable amount of lime, and, except the edge, he would not dip a chisel in it. Men working at Penarth, Barry, or Porthcawl would have to be guided by their knowledge and experience of the local water in regard to the extent of their dipping, in the treatment of hand-tools. There was diversity of opinion as to putting the chisel in water. There were some who deemed it advantageous to turn the chisel obversely or upside down and to put it in the water, thus cooling right off, drawing it down again to the colour desired either in a tube or a piece of flat iron red hot. This seemed to be the nearest method to the scientific ideas suggested in the Paper. Much depended on the quality of the steel used ; some high-carbon steel tools could only be tempered in oil, and with considerable care exercised in securing a uniform heat. Hence, the gas-heated furnace seemed the safest means of achieving the best results.

Mr. GEORGEREEVES said when he used the expression that every man had his own ‘‘ fad,” he did not imply any imputation of slovenliness. He only intended to convey the meaning that some men thought their way of doing the thing was the best, and it might be that all their methods had something to recommend them. He believed that frost played a very prominent part in causing steel to fracture, and mentioned an experience of collecting some liquid air in a vacuum glass and placing into it a piece of india- rubber. When the latter was withdrawn, it could be broken more easily than glass, and it regained its usual flexibility after the natural atmosphere had thawed it. He thought that frost acted on steel tools in the same manner, but in a lesser degree.

Engineer-Lieut. W. H. REYNOLDS,R.D., R.N.R., said he was of opinion that they could not standardize a tool like the chisel. What might well apply to the Midland Railway Company’s shops

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 FEB. 1916. CHISELS. 167 might not-and would not-apply to other establishments. Under different conditions and classes of work there must be different methods. For instance, there were certain parts of a marine engine in course of ,construction which could not be touched with a pneumatic tool and must therefore be done by hand. He had a vivid recollection of chipping what was called ‘‘ bye-metal ” in his early days in the shops-where the flanges of the columns met the feet on the cylinders, a large amount of metal was left on the castings and the only way to get it bff was to chip it by hand. Very often the surplus material would be as much as Q inch in thickness and the full depth of the flanges was very commonly 4 inches each in depth. The method was to gutter or channel the metal to be removed, and afterwards to break off the intervening projections and finally to dress down the whole with a light cut. The chisels used for guttering were termed ‘‘ Cape ” chisels, and it was found that not every smith in the tool shop could properly temper the Cape chisel. There was generally one man who could do it better than others. This man had no scientific or theoretical knowledge, but he probably possessed a practical secret which he took care to keep to himself. The steel supplied from the stores to the tool smiths for chisel-making was identical, and although there would be possibly a dozen men employed on tempering tools, probably only one .man would properly dress and temper a Cape chisel for the particular work for which it was needed. Thus a great deal depended upon the human element and upon the class of work to be done. The method of treating the steel would also vary according to the character of the job upon which the hand tool was to be used. As to heating chisels in a gas-fired furnace prior to tempering, chisels had to be used in various places, and under various conditions where it would not be possible to resort to what he might call laboratory methods. He remembered that many years ago he was on the engineering staff of a ship in an out-of-the-way part of the world; they were badly in want of good tools in a heavy main-shaft repair. Considerable difficulty was experienced

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 168 CHISELS. Fm. 1816. (Engineer-Lieut. W. H. Reynolds, R.D., R.X.R.) in completing the job, due to the fact that there was not one amongst the engineers on board who could dress and temper a chisel suitably for the heavy work in hand, although they were all more or less acquainted with the usual shop methods. As he had said, the necessarily varying conditions and kinds of work in which, and for which the chisel was used, made tempering by a standard method impracticable in his opinion. The success of a chisel did not always depend upon tempering alone. For certain classes of work, the shape of the chisel throughout was distinctly of importance.

Mr. DOUULASE. CAMERONsaid that when firms were asked to tender for the supply of steel to be used for a specific purpose, it was surprising how their prices varied, and yet they would profess that their particular steel was the best for that purpose. The range in price, however, was so wide that it was evident there was great difference in the composition of the steel. If one asked for steel to the Author's specification, he thought it would be difticult to obtain. Every firm had its special steel, and would refuse to divulge its composition. Some purchasers could only trust the manufacturer and test the steel afterwards. He inferred from the Paper that the Author confined himself to specifying the carbon content only when ordering steel, which was probably the best way.

Mr. W. G. WEBBsaid his experience taught him that 10" of difference in temperature of the furnace made all the diference between failure and success ; and, with reference to the oil-bath, the process took about 20 minutes before the steel was raised to the desired temperature.

Mr. FREDERICKJONES said he would like the Author to favour them with more information on the results of his experiments on the difference between hardening steel in water and the use of the oil-bath. He felt that a good deal of success in hardening steel depended upon the human element, and was inclined to think that the chisel, if made shorter, would do more work.

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Mr. JOHNMARSHALL said he wished to speak as A practical blacksmith employed in everyday practice in ordinary shops- not in such large establishments as that of the Midland Railway Co.- and in his opinion the Author’s method was a little too elaborate. It might be all right in a large shop, but at places where probably there were only two tools of each class, the blacksmith was bound to attend to them without delay. The previous speaker had suggested a shorter chisel, The average chisel was 8 inches to 9 inches long, and might be unhandy at first, but it soon wore down and became too short. As to tempering, there were various ways, and different steels required different methods. A blacksmith would make a mistake at times; it was impossible to avoid it. Even with the method described in the Paper there would be mistakes. To temper a strange chisel was an experiment. If it came back to the blacksmith broken or bent, he knew it needed more or less hardening ; but it was also necessary for him to know what metal the chisel was going to cut.

Mr. THOMASH. NASHsaid a question had been put as to the effect of frost on the chisel. He was quite satisfied that sudden frost caused steel and iron tools to snap. As to tempering, he preferred rain-water, unless the publicly supplied water was very soft, in which to dip the chisel, and a good plan was to take the chill out of the water before plunging the chisel into it. He did not agree with the suggestion that the chisel should be composed of two portions, and that the head portion should be harder so as better to withstand the blow of the hammer. The chisel, becoming worn, got shorter, and if it were tempered properly, the wear was chiefly on the head. To overcome the difficulty, he would suggest that the head should be slightly hardened. If the chisel were in two parts, a certain percentage of the blow would be taken up in the joint, however securely it was made and fitted. There were very few working men-including himself-who understood the proper composition of steel ; and in most shops it was very difficult to have the equipment for carrying out the practice described.

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Mr. C. A. JAMESsaid the view he held of the eEects of sudden frost on the chisel was that the user’s hands got chilled with the cold steel ; he was not able to deliver a fair blow, and it was the jar that caused the fracture. He agreed with Mr. Davies that the best way to temper steel was to dip it and cool out, brighten it, and run the colour or temper down. In his amount of carbon in the steel Mr. Fowler differed from Seebohm, another authority on steel, who stated that, for razor tempering, steel should have 14 per cent. of carbon, soft file tempering 1% per cent. carbon; tool tempering, 1; per cent. carbon (this was probably for drills, turning tools, etc.) ; spindle tempering, 14 per cent. carbon, and chisel tempering, 1 per cent. carbon. He (Mr. James) did not agree with the speaker who regarded spindle-steel as requiring less carbon than the ordinary chisel-steel. In regard to cold sets, such as double-handed tools for heavy hammer work, the figures were more in accordance with Mr. Fowler’s statement, giving 4 inch depth for die tempering and 2 per cent. of carbon. On the question of water, he did not think any one could make a mistake in using soft rain-water. Water varied in hardness in different localities. It was usual to heat the water a trifle, but he thought that what the Author aimed at was to heat the steel sufficiently to plunge it out, in oil, so that every chisel should be alike, and that there should be no division. There again, while the Author gave the standard elements in the steel, he did not treat of the density of the oil, which was a material factor. He had proved it in tests with whale oil, with linseed, and with colza oils, and found that the density of the oil had a most important bearing, even according to the Author’s method of getting the true result.

Mr. A. E. HOPEINSremarked that he did not agree with the suggestion that the head of the chisel should be hardened.

Mr. FERDINANDRICHARDS thought the Author’s processes could only be profitably carried out in large establishments where chisels were made in huge quantities. As to the proposal of a speaker to economize in steel, by putting a joint between the cutting bit of the

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 FEB.1916. CHISELS. 171 chisel and the shaft, the blow would not be transmitted to the point at its full force, and he did not think the suggestion would be effective. Welding a tool-steel tip to a mild-steel shaft would be a better method, but probably not worth the trouble when the chisel-steel used was comparatively cheap and not an expensive alloy.

Mr. WILLIAMJ. SLYsaid the whole question largely depended upon local conditions. Firms like his own, which only bought steel in small quantities, could not buy to specifications ; they must rely upon the name of the steel. A few months ago his firm bought some air-hardening steel as distinct from self-hardening steel- hardened in the cold-air blast. The foreman blacksmith-a man of forty years’ experience-could make nothing of it for three or four weeks. Then the correct process was discovered. They heated the steel very slowly to a blood-red, forged, and cooled it in ashes ; it was next heated to a cherry-red and put into the blast of a dead forge. The steel was found to answer fairly well, both as turning- tools and chisels. The Author confined himself to hand-chisels. In out-of-the- way country works they had often to use double-handled chisels. He had seen a chisel 5 feet long, with a 14 lb. sledge on the top. Experience proved that the two-handled chisel had to be considerably less hardened than the hand tool. But with a heavy hammer behind it a chisel, which would double up as a hand-tool, wouId cut quite well, even with a 14 lb. sledge on it. In quarries in Lancashire he had seen jumpers 20 feet long used in drilling rock. The point and the top were steeled, but the top was not hardened. It was quite possible to have the point hardened even with a wrought-iron stem, provided the stem was stout enough. To the pinch bars used in the quarries at Penarth there was a heel at one end and a chisel point at the other, both being shut on to mild steel. This was also a common practice in repairing pickaxes. With regard to various grades of steel, in Lancashire they had some old Bessemer steel rail, and a chisel was made out of it as a

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 172 CHISELS. FRE. 1016. (Mr. IVillinm J. Sly.) curiosity, which was in use for many months. It dressed the local limestone satisfactorily, and with hardening it would even cut mild steel fairly well. He regarded the Author's methods of hardening as of rather an academic nature. There were the personal element as well as local conditions to be considered, When he (Mr. Sly) was serving his time, in the days of the ordinary cast-steel, fine chisels or milling cutters used to be hardened in boiled oil. It was thought that they stood up to the work better; whereas if they were'heavy tools they were just plunged as had been described. With regard to the effect of frost on steel, he had several times seen small files snap on falling to a wooden floor on a sharp winter morning, but whether the cause was purely atmospheric he was not prepared to say. The whole subject was most interesting to the engineering world, and in view, too, of the cost in lost time due to faulty tools, the matter was of great importance.

Mr. E. GORDONDAVIES said it was the general view of the workmen that frost caused chisels to snap. He himself knew of a case where a chisel, which had lasted for years, was accidentally dropped three feet on a frosty morning, and it broke, The speaker described a woodworker's chisel, 34 inches in width and 14 inches square section in the shaft, with bevelled corners. It was used by a railway-wagon carpenter, and was of solid cast-steel throughout, with a slightly hardened head to prevent spreading under the hammer. It was used on oak, for almost a week on end, with a 7 lb. hammer, and the head maintained its shape perfectly, neither spreading nor chipping off.

Mr. E. P. EDWARDSsaid he believed importance was to be attached to the way in which the tool was introduced to the bath. This was usually done in a more or less haphazard fashion, but he understood that, in the matter of taps especially, these should be suspended as perpendicularly as possible and the bath brought up to the tool, the reason being that if the tool, in quenching, was held out of the perpendicular, distortion was likely to occur owing to the temper not being equal up the tool.

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Mr. S. W. ALLENrecalled that in his early days the workman was always very careful and proud of the tools he used. There was no doubt the old blacksmith knew much about hardening, as might be seen in the wonderful chisel work of the Egyptians in the Sphinx, and in other carved stones of the Ancients.

The CHAIRMANsaid he was gratified that they had had so good a discussion, and he was sure Mr. Fowler would be very pleased to learn that his suggestive Paper had evoked so many views. As to the shape of the chisel, he did not think this point was raised during the discussion in London, but it was certainly one worthy of consideration. He recalled some chisels that were made out of steel about 1 inch wide and 3 inch thick, with rounded edges, that had done most excellent service. A thin flat chisel required less hammering, and was probably less disturbed. The only steel dealt with in the Paper was ordinary crucible steel, and when the Author was asked at the Meeting in London whether he had considered the use of any form of alloyed steel, he replied in the negative. He (the Chairman) might say that the Institution was now considering the formation of a small Committee to go thoroughly into the whole subject, and one matter of inquiry would be the composition of the metal which might be suitable to this kind of percussive action, and then to follow this up by careful consideration of the best system of hardening and tempering. At the discussion in London Sir Robert Hadfield, the maker of the manganese steel to which reference had been made, said he thought the addition of chromium to the mixture would produce a chisel that would stand more harsh treatment. The effect of frost upon steel had been mentioned. He was convinced that frost did have a distinct effect upon all metallic substances, especially upon castings of odd shapes, that would have certain stresses still remaining in them. When he was more actively engaged in the works, he never got so much trouble from breakdowns of one kind and another as at the first burst of frosty weather. He was interested in hearing Mr. Allen refer to the old days. He himself was old enough to remember slot links and N

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 174 CHISELS. FBB. 1916. (The Chairman.) other similar parts being prepared with a hammer and chisel, which were now executed in a shaping or milling machine, and good jobs they were, too. In conclusion, he desired to thank those present, on behalf of the Institution of Mechanical Engineers, for their attendance and for the interest they had manifested in Mr. Fowler's Paper.

On the proposition of Engineer-Lieut. W. H. REYNOLDS, seconded by Mr. FREDERICKJONES, a cordial vote of thanks was passed to the Chairman.

The CHAIRMAN,in acknowledgment, said he hoped there might be other opportunities locally of debating subjects arising at the Institution of Mechanical Engineers. It all depended upon whether they were sufficiently interested to come and express their views as practical men upon matters which, after all, directly concerned them. The Meeting then terminated.

(The Author's Reply to the Discussion toill be found on page 182.)

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Communications.

Mr. WILLIAMH. ALLEN( Vice-President) wrote that, as promised in the course of the Discussion at the London Meeting (page 149), he now sent some additional information. The method employed at the Queen's Engineering Works, Bedford, was what the Author described as one of " the old rule-of- thumb methods," but it had always given very good results. The material was A.W. cast steel, containing about 0.825 per cent. of carbon, and this apparently varied very little in quality. The carbon percentage was within the limits specified by Mr. Fowler. After drawing out and allowing the chisel to cool, the point was heated to a bright red heat, about 850" C. (1,562' F.) for a distance of about 1 inch, and then quenched in cold water for a distance of 4 inch to 4 inch from the end. The end was then taken out of the water and the hardened point tempered by the heat conducted from the unquenched portion. As soon as the cutting edge had reached a purple or deep blue, 280"-320" C. (536'-608" F.), the whole tool was again quenched. The foregoing treatment gave maximum hardness at the point, with decreasing hardness the farther one went from the point, for two reasons :- (a) The chisel was at thinnest section at the point, and therefore was chilled most suddenly in quenching, the thicker portions behind losing their heat not quite so suddenly. (6) The extreme point was less tempered or let down than the rest of the tapering portion. The effect of this gradual decrease in hardness was shown by the curves of Shore Scleroscope figures for different distances from the point, Fig. 12 (page 178). Whether this gradual decrease in hardness was unsatisfactory would be discussed later. In practice it was found that a large proportion of the chisels sent for repair had been used until they were too thick to chip properly, thus N2

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 176 CHISELS. Fm. 1916. (Mr. William H. Allen.) showing that they had been hard enough for the work. After fr inch or 4 inch had gone, it was necessary to draw out again and re-harden. The method certainly required some skill on the part of the operator, and this was almost entirely done away with in Mr. Fowler's method, the only point where it came in, in the latter, being in the testing of the chisels with a file to ascertain whether they had been a sufficienttime in the tempering bath. To test the method recommended by Mr. Fowler against their own, experiments had been carried out on four new chisels of the same dimensions, two of which were hardened and tempered in their usual manner, as described above, the other two being treated as far as possible by Mr. Fowler's method. The shape and size of the chisel were approximately as shown in Fig. 11.

FIG.11.-Type of Chisel used.

In carrying out the treatment as described by Mr. Fowler, the quenching of the point was carried out at 740" C. (1,364" F.), while in tempering, one of the two chisels was left in the oil-bath for 10 minutes and the second for 15 minutes. It should be pointed out that Mr. Fowler did not give any data as to size of bath, method of heating, or length of time occupied in tempering. The tempering again was carried out over a range of temperature depending upon the amount of fall in temperature of the bath below 215' C. (419' F.) caused by putting in the cold chisels. The length of time taken in tempering had considerable effect; for example, the same temper might be obtained by short exposure to a certain temperature, or through longer exposure to lower temperatures. It was therefore only possible to attempt to reproduce Mr. Fowler's method, and any criticism which might follow was to be understood as only referring to the method as

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tried at the Queen’s Engineering Works, and not to that in vogue at Derby. After finishing two chisels by each method, it was intended to use the Brine11 hardness machine on all four, and the two treated by his firm were so tested; but the first of the two treated by Mr. Fowler’s method fractured in the second test under the ball, and it was decided not to risk the other in the same way, 8s a working test was also desired. Shore hardness tests were therefore made. The results obtained were as follows :-

‘reated by Messrs. W. H. Allen, Son and Treated by Mr. Fowler’s CO.’S Method. Method. /I No. 4 No. 1, tempered 15 mins.).

Shore Shore Shore )istance listance Distance mrdness hardness hardness porn end. ,omend. figure. rom end. figure. figure.

inch. inch. inch. (inch. 0.14 67 0.23 65 i 64 iear end 68 0.18 65 0.23 0.26 64 64 1 0.28 62 0.32 64 0.35 62

0.35 59 0.37 55 0.39 61

0.40 55 0.40 47 0.45 60

0.42 53 0.43 47 0.54 51 0-50 46 0-48 40 0.5G 47 0.57 42 0‘54 36 I 0.71 40 0.63 28 0.63 0.99 37

31 ~ 1 maximun. rest of rest of 34-36 36- 37 chisel. 28-30 chisel. softness.

These results were shown plotted as curves in Fig. 12 (page 178).

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0 0.2 0.4 0-6 0.8 1.0 DISTANCE FROM POINT IN INCHES

The Brinell tests, as far as they could be carried out, were as follows :- r Treated by Messrs. W. H.Allen, Treated by Son and Co.’s Method. Mr. Fowler’s Method. . I I No. 3 No. 4 No. 1. No. 2. temperedlomins.). (tempered 15 mins.) - Xstance 3rinell Distance 3rinell Distance Brinell rom end. Sgure. rom end Bgure. rom end figure.

inch. inch. inch. 0.14 570 0.26 520 0.25 630 0.23 570 0.31 520 0-35 racturei Not tried by 0.30 570 0.43 370 0.45 ‘racturec Brinell test, 0.43 570 0.49 296 - - being reserved for 0-5 318 0-60 250 - - a working test. 0.57 276 - - - - 0.72 258 - - I’ - - - I1 Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 FEB.1916. CHISELS. 179

The discrepancies, where they occurred, between these figures and those obtained from the Shore instrument were due to the fact that the circular depression obtained in the Brinell test extended over a much larger area, over which the hardness might vary somewhat. Taking the results of the Shore Scleroscope tests, from which comparative figures were obtained, it would be seen that there was very little difference as regards the hardness of the extreme edge of the tool, but there was a more rapid falling-off in the hardness along the tapering portion in their method than in Mr. Fowler's. The reason for this had already been referred to, In Mr. Fowler's method there was uniform tempering of all the hardened portion, but to a less extent than with them, and in the former method any decrease of hardness taking place over a quenched and tempered portion must be due entirely to difference in rapidity of quenching caused by the increasing thickness. An ordinary test was also tried with chisels Nos. 1, 2, and 3, these being used by the same operator, who did not know which was which, on hard steel, cutting on the flat, with the whole edge of the chisel-a very severe trial. Nos. 1 and 2 chipped slightly, while in the case of No. 3, the whole edge broke away. This rough practical test should of course hardly be taken as conclusive. Taking all the tests together, the following conclusions seemed to be reached :- (a) Mr. Fowler's method as tried at Bedford produced, if anything, a slightly more brittle working point. This was to be expected, because the temperature of tempering, 220" C. (428O F.), was decidedly lower than with them (my 280-320' C.), and it was their experience that better results were obtained by tempering at a higher temperature. This was confirmed by tempering some chisels to a straw-yellow (say 220" C.), when they chipped very much more badly, employing the same test, than when tempered to a blue. (b) In actual working, after the very hard point has been partly chipped or worn away during use and partly ground away in re- sharpening, the chisel as treated by Mr. Fowler's method was somewhat harder than was obtained in their method. This was an advantage, but was hardly sufficiently to justify the extra trouble and expense.

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 180 CHISELS. PER. 1916. (Xr. William H. Alleu.) (c) Although the quenching of the rest of the chisel in oil from about the critical temperature of the steel, after hardening the point in water, would probably produce a sorbitic structure, giving R tough shaft capable of withstanding the blow of the hammer without chipping, this appeared to have no very pronounced advantage over their own method, since neither chipping of the shaft nor excessive softness was ever a source of trouble with them. (d) In general, while in Mr. Fowler’s tnethod, given a correct tempering temperature, a more regular article might be produced, the human factor being almost eliminated, there was apparently no serious fault to find with the usual rule-of-thumb method, which, not involving a separate and distinct operation for tempering, was much cheaper and quicker than the other would be. In this connexion it might be of interest to reproduce, from Howe’s ‘‘ Steel,” the following abridged Table of hardening temperatures for chisels :-

___~ -___ Carbon in Temper Colour. Temperature. Uses of the Steel. Steal. ____

O c. O F. Per cent. [Cold chisels for cutting - Golden yellow . 243 469 steel . . . . Brown . . 255 491 Cold chisels . . . 1.3 Purple . . 277 531 Cold chisels for soft iron - Violet . . - - Cold chisels for brass . 0.9 (Chisels for wrought-iron - Dark blue . 316 600 and copper. . . -

Thus for chisels for different purposes, steels of very different carbon-content were employed, since a harder material should be required for use on steel than on copper. They found, however, as did also Mr. Fowler, that one quality and hardness mas sufficient for all purposes. Their work was largely on steel and hard cast-iron, and it was possible that the chisels used at Derby

Downloaded from pme.sagepub.com at WEST VIRGINA UNIV on June 4, 2016 FEE. 1916. CHISELS. 181 might-be generally working on softer materials. This would explain the difference in temperature of tempering found to be most suitable. With regard to the need of normalizing at 900' C. (l,6!5S0 F.) after forging and before hardening-a treatment tried by Mr. Fowler-the intent being .to remove the unequal effects of the stresses of forging, it should hardly be expected that this process should be necessary or have much effect. A temperature of 730" or 740" C. (1,346"-1,364 F.) was above the upper point of the critical range for a 0.8 carbon steel, and the effects of the previous work should be sufficiently removed by the heating before hardening. Mr. Fowler noted that no improvement had been obtained by the normalizing.

Mr. S. WHPTEwrote that he thought the heat-treatment of each type of chisel might be found experimentally, so as to give the proper microscopic structure corresponding to that of the chisel, which had given the best result in practice, and so standardize the treatment; while in some cases the study of the structure might help to obtain still better results. The chemical analysis would give the temperature from which to quench, but the length of time of dipping in the water before transferring to the oil, and whether the water should be cold or warm, could best be determined for the different sections, when it was known whether it were a purely martensitic structure or a mixture of martensite and troostite that was wanted at the cutting edge for the particular chisel under consideration. Instead of varying the quenching temperature for the different sections, the temperature which gave the best grain might be kept, and the method of dipping altered to give the desired structure.

It was obvious that the subsequent tempering, or '' letting down " in the oil-bath, would then be more or less a constant, and would do away with the necessity of testing the temper with a file. It was interesting to find that Mr. Fowler had found no advantage in normalizing the steel after forging, but if the steel were badly overheated in forging, or were worked at too low a heat, one might expect an improvement by normalizing before hardening.

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Mr. HENRYFOWLER, in reply to the discussion at Cardiff, thought that the chisels mentioned by Mr. Faraday Proctor (page 160), as used in France, were only suitable for light work. With regard to the question of special steels, as stated, he had not tried these, but he trusted that if the small Cpmmittee were formed, as suggested, exhaustive experiments would be made with them. This Committee would also probably be able to deal with the question of the mechanical testing which had been raised by several members. In reply to Professor Bacon (page 162), the chisels were taken out of the furnace one by one, and simply passed through in batches of fifty. The oil-tank used in tempering was sunk into a cold-water tank which surrounded it, and had a stream of water passing through it. In a large works a considerable number of chisels were dealt with, and so a whole batch was put through at once. The Author was aware that not in every works could such a system as that described be carried out, although undoubtedly in works of any size some modification could be adopted. There was no doubt that an experienced smith, working with a steel with which he had been long acquainted, could obtain good results, but the object of the investigation was to eliminate the personal factor as far as possible. He regarded the experiments carried out by Mr. William H. Allen (page 175) as of very great interest, especially those which referred to the hardness fignres.

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