Meridian Agriculture Department Welding I METALS BOOKLET Name: ________________________________ Date: _________________________________ 1 2 Cold Chisel Angle TOOL SHARPENING GAUGE Construction Procedure: 1. Square one corner of aluminum or brass stock. 2. Measure and scribe outline on stock with awl. 3. Mark graduations with awl. 4. Cut out tool gage with hacksaw. (Use protective blocks on each side when cutting in vise.) 5. Dress to the lines with file, bevel corners. 6. Use three-square file to cut chisel vee. 7. Polish with steel wool. 8. Submit to instructor for evaluation. 9. Drill size holes ¼”, 3/16”, 1/8”, and 1/6”, may be drilled in the Twist Drill body of the gage. Cutting Angle Questions: 1. Why is aluminum easier to work than brass? o 2. Why is it important to square or make a corner 90 ? 3. Which hacksaw blade did you use; 18-24-32? Why? 4. When should you use draw filing? Cross filing? 5. Why should files always be fitted with handles? Back Rake Angle Evaluation score sheet: Points Item Possible Earned 1. Length of gauge 10 _____ Gage can be used to measure: 2. Width of narrow 10 _____ 1. Cold chisel cutting angle 3. Width of wide end 10 _____ 2. Twist drill, cutting edge 4. Vee position for cold chisel angle 10 _____ 3. Twist drill, lip clearance 5. Angle for drill cutting edge 15 _____ Bill of Material: 6. Accuracy of the 1” and 1/2” rules 10 _____ 1-7/8” x 4-1/16” x 3/32” 7. Angle for drill lip clearance 10 _____ Aluminum, brass or mild steel 8. Correct angle and size of bevel corners 5 _____ 9. Finish 10 _____ Name_______________________ 10. Attitude and work habits 10__ _____ Date________________________ Grade_______________________ 3 HACKSAWS 1. Hand hacksaw a. Frames (1) Adjustable – This is the most popular frame for general use. They vary in depth from 2- 1/2” to 3-1/2” and will take blades from 8” to 12” in length. By loosening the wing-nut, the mounting posts may be turned so that the blade will cut at right angles to the frame. (2) Solid – Frames may be had that vary in depth and length. They remain very rigid and for specialized work are very desirable. b. Blades (1) A blade should be selected that will be best suited to the work being done. In most Cases, it is desirable to select 10” to 12” blades for use in adjustable frames. (2) The blade should have enough teeth per inch so that two or more are in contact with the metal at all times. Standard blades are 7/16” to 9/16” wide with 14 to 32 teeth per inch and 8” to 12” long. Blades with 18, 24 or 32 teeth per inch are used most. 2. Cutting metal with a hacksaw a. Mount the blade in the frame so that the teeth point forward. b. Tighter the tension out so that when struck with a piece of metal, the blade gives a slight ring. c. Clamp the work securely so that two or more teeth are in contact with the metal at all times. d. Saw close to the vice to prevent vibration. e. Thin material may be placed between two blocks of wood before sawing. f. Grip saw firmly; one hand on handle and the other holding front of frame. Make each stroke go full length of blade. g. Apply pressure on only the forward stroke then lift slightly on the return stroke when sawing hard metal. h. Always start a new cut when replacing a blade. i. Use approximately 35 to 50 strokes per minute – 80 strokes should be the maximum. Hard materials overheated and dull blade when sawed too fast. 3. Most common causes of blade breakage or failure a. Using a saw with large teeth to saw thin metal. b. Using too much pressure. c. Sawing too fast. d. Using short strokes, causing excess wear and loss of set. e. Insufficient tension on blade f. Failure to give work proper support. g. Failure to hold saw firmly and push straight forward on the cutting stroke and return straight back. 4 4. Filling Cold Metal The file is used for smoothing and shaping metals. Shaping actually includes three types of file use: sharpening of tools, smoothing metal surfaces, and cutting metal to the desired form and dimensions. A regular mill file can also be used to test the hardness of metal. The degree of hardness will determine the type of metal cutting tool and/or the type of hacksaw blade to use for making the cut. 5 a. Files are selected according to their many uses. The use of a file determines the size, type of teeth, coarseness, and shape. (1) File Sizes – File sizes are determined by the length of the file ( in inches) excluding the tang or the distance from the point to the heel. A 10-inch mill file is used for general purposes. A 12-inch flat file is best for rough work and will last longer than a 10-inch file. (2) File Teeth – There are two major kinds of file teeth, single-cut and double cut. Single- Cut files have chisel-like teeth running at an angle across the belly and body of the file. Double-cut files have two sets of teeth or chisel cuts that cross each other. Single-cut files cut slower then double-cut files, and they leave a smoother surface. (3) Grades of Teeth Coarseness - The grade of coarseness is determined by the distance between the rows of teeth. For example, the longest spacing is called rough, and the least spacing is dead-smooth. Naturally, the coarseness changes with the length. A long file is coarser than a short file. TEETH SPACING OF SINGLE-CUT FILES The most commonly used files are the bastard, second-cut, and smooth. Rough, coarse, and dead-smooth files are used for special work. (4) File Shapes – The shape or style is also determined by the different uses. The most common are mill, flat, square, round, half-round, and taper or three corner files. A description of these files is as follows: (a) Mill files are made only with single-cut teeth and range in size from 4 to 16 inches. They are used for drawfiling and finishing work such as finishing brass and bronze metals. 6 (b) Similar to the mill file and are the most commonly used of all files for general work. (c) Square files have four filing edges instead of two as round on the mill and flat files. They are tapered or blunt and double-cut. This kind of file is used to filing corners and slots and for surface filing. (d) Round files are single or double cut. They are used for enlarging holes, filing curves, and forming fillets. These files are tapered from shoulder or heel to point. (e) Half-round files have one flat side and one partly round side (about one-third of a circle). This type of file is double-cut, and it can be used to file either flat or curved surfaces. (f) Tapered files are found in many shapes. The Triangle, contour, and cross-cut files are the most popular. They are double cut and are used to file corners that are less than 90 degrees and to file saws. 7 There is a correct way and many incorrect ways to hold a file for both heavy and light filing: (1) Heavy filling – The handle is held in one hand by placing the thumb or forefinger on top of the file handle and gripping the point with the fingers and back part of the thumb. Tang Heel Body Bell Point Length 8 Wood File Handle (for safety) (2) Light Filing - The handle may be held the same way as in the heavy filing method. The file point is held between the first two fingers and thumb, applying light to moderate pressure as needed. c. The steps to follow when using a file to shape metal are: (1) Clamp the stock (metal) slightly above the jaws of the vise to eliminate vibration while filing. The area being filed should be about elbow height or slightly below. Chattering can be reduced or almost eliminated if the stock is placed just above the jaws of the vise. Machinist Bench Vise (2) Select the proper type file to cut the stock. For example, if the surface is to be filed flat, select a flat file. (3) Stand slightly to one side of the work, yet facing it so that the right amount of pressure can be applied on the forward stroke. (4) Use moderate speed strokes. However, hard metal is filed slower with more pressure than mild 9 or soft metal. About 30 strokes per minute may be appropriate. (5) Except for filing, hold the file at a 90-degree angle to the side of the stock when making filing strokes on flat metal. (6) Make a slow, full-length stroke by placing the file on the stock and pushing it forward; lift it on the back stroke. Moving the file back, permitting it to slide over the metal, will dull the teeth faster than pushing the file forward. If there is a possibility of the file slipping off the stock on forward stroke and marking or damaging the jaws of the vise, the stock should be clamped between two pieces of board. (7) Check the stock with a square during the filing process to see if a proper cut is being made.