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Drilling, Tapping & Threading

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Drilling, Tapping & Threading DRILLING, TAPPING & THREADING (DTT) Learner Guide TABLE OF CONTENTS INTRODUCTION PAGE 1 PROGRESS SUMMARY - PRACTICAL TASKS PAGE 3 DRILLING - DTT-1 SUMMARY NOTES PAGE 4 THEORETICAL EXERCISE PAGE 9 CRITERION TEST PART B PAGE 11 CRITERION TEST PART A PAGE 12 PRACTICAL EXERCISE PAGE 14 DRILL SHARPENING - DTT-2 SUMMARY NOTES PAGE 15 PRACTICAL EXERCISE PAGE 17 CRITERION TEST PAGE 18 HAND TAPPING - DTT-3 SUMMARY NOTES PAGE 19 PRACTICAL EXERCISE PAGE 22 CRITERION TEST PAGE 23 THREADING BY HAND - DTT-4 SUMMARY NOTES PAGE 24 PRACTICAL EXERCISE PAGE 30 CRITERION TEST PAGE 31 CONTACT DETAILS: https://techav.co.za [email protected] THE DRILLING, TAPPING & THREADING SELF INSTRUCTION PROGRAMME INTRODUCTION This programme has been designed to provide you, the learner, with the necessary basic information to perform essential metal work skills. Your primary source of information is a video programme. The video shows you what you need to know. Together with this workbook, your Course Controller and the video programmes you will receive enough input to enable you to: i) Drill holes, accurately and safely, into metal work pieces. ii) Produce well-formed threads in holes. iii) Produce well-formed threads onto round bars. However, what this programme cannot give you is EXPERIENCE! This is something that only you can provide - through PRACTICE. HOW TO USE THIS MATERIAL 1. Read through this workbook. 2. Watch each video programme to see how things are done. 3. Practice the procedures demonstrated in the videos. This workbook contains certain exercises, some theoretical, some practical. All questions are based on a "must know" or "should know" principle. Answer the questions firstly in pencil, then, have your Course Controller check and correct your answers. Thereafter write them in ink. Keep this workbook as reference for the future. 4. Your Course Controller will allocate relevant work exercises according to the type of work and the conditions existing in your place of work or your training-centre. Remember! - Your Course Controller is there to help you. If you do not understand something or if you need assistance, ASK. 5. When you think you have had enough practice and have learned the material thoroughly, then ask for the CRITERION TEST. The criterion test is performed by you, without assistance and is based upon whether you can perform the tasks demonstrated. There are NO tricks to the criterion test - you are simply marked on your ability to perform the work and supply relevant information. 6. Have your Course Controller update your progress summary as you complete each task. SUMMARY OF LEARNING PROCEDURE 1. Read through this workbook. 2. View each video, beginning with DTT-1. 3. Re-view each section of video. Stop when you see a "discussion logo" or "practical logo". 4. Switch off the video during discussion or practical breaks and perform the suggested exercise, or that task given by your Course Controller. 5. Practice each task demonstrated at your own workbench. Back to Table of Contents 1 6. Perform a criterion test - given to you by your Course Controller. FURTHER STUDY MATERIAL 1. Study the SOMTA users guide for drills and taps. 2. Study SOMTA wall charts on drills and taps. A THOUGHT Give instruction to a wise man and he will be yet wiser. Proverbs 9:9 Back to Table of Contents 2 PROGRESS SUMMARY - PRACTICAL TASKS DRILLING, TAPPING AND THREADING (DTT) LEARNER: _______________________________________________________________ TASK ATTEMPT NO. CRITERION DATE INSTRUCTOR 1ST 2ND 3RD 4TH ATTAINED SIGN Drilling (port) YES NO Drilling (bench) YES NO Drill sharpening YES NO Hand tapping YES NO Threading YES NO NOTE 1. Competency must be attained on maximum 4 attempts. 2. Instructor or Course Controller to sign off only on attainment of competency. Back to Table of Contents 3 DRILLING, TAPPING AND TREADING PART ONE: - DRILLING (SUMMARY NOTES) Reference Material: - Video DTT-1. - SOMTA User Guide - "Drills, Reamers, Taps". - The operator's manual for your bench and portable drilling machines. AN OVERVIEW The primary purpose of drilling is to produce a hole in a given material. To produce holes in metal we need the assistance of: 1. A twist drill. 2. A drilling machine. TWIST DRILLS There are several types of twist drills each designed for a specific purpose. For an explicit overview of types read pages 7 - 11 in the SOMTA User Guide (Drills, reamers & taps). The drills used in the demonstrations (re: video programmes) are of the "general purpose, high speed steel" (H.S.S.) types. DRILLING MACHINES Nowadays most metal work drilling is performed using an electrically powered machine of one kind or another. The video programme demonstrates a "portable machine" often referred to as a "hand-machine" and a "fixed machine". A fixed machine cannot be moved around and is bolted to a bench or to the floor. The Radial type machine is not within the scope of this programme but will be covered in more advanced "machine-skills" productions. Back to Table of Contents 4 BENCH TYPE (Bench or bracket mounted) PEDESTAL TYPE (Floor mounted) RADIAL MACHINE Back to Table of Contents 5 TYPICAL FIXED TYPE DRILLING MACHINES. PRACTICAL USAGE OF DRILLING MACHINES A. PORTABLE TYPES: - Key points to remember. 1. Only use the "hammer action" when drilling into masonry. 2. Perform a safety check before using. 3. Return a faulty machine to your stores for attention by a qualified electrician. 4. Always protect your eyes - wear safety-goggles. 5. Ensure that cables (extensions etc.) do not layover walkways, vehicle accesses or sharp edges. 6. Never work in wet conditions. 7. Wear proper shoes - with rubber or insulated sales. 8. Carry the machine by its body, not by the power cord. 9. Make a centre-punch mark at the centre of the drilling position - this will prevent the drill from running-off. 10. Fit the drill into the chuck in such a way that the shank only is gripped. Approximately ⅓ of the shank should be visible when the drill is properly installed. 11. Check that the drill runs true i.e. it does not wobble. 12. Select the correct speed - Slow for large drills (7 - 13 mm). - Fast for small drills (0,5 - 6 mm). 13. Keep the drill at 90⁰ to the work surface. 14. Use the support handle on larger machines to ensure that the machine does not twist out of your hands should the drill snag. 15. Maintain enough pressure to keep the drill cutting. Ease up on the pressure and keep a firm grip on the machine as the point breaks through the material. 16. Allow the drill to cool before removing it. B. FIXED TYPES: - Key points to remember. As fixed machines have several features we shall break the operations down - into the key areas. 1. INSTALLATION OF MORSE TAPER DRILL o Ensure selected drill is clean and dry. o Ensure that the female taper in the spindle is clean and dry. o Insert shank into the spindle taper, twist it until you feel the flat "tang" engage the location slot within the sleeve. o Secure the drill by pulling down the operating handle and pressing the point onto a piece of timber. 2. INSTALLATION OF STRAIGHT SHANK DRILLS (Parallel shank) o Firstly install the chuck into the spindle in the same manner as installing a taper shank. Back to Table of Contents 6 o Select drill to be used and check drill point for damage and shank for scoring. o Install the drill in such a way that the shank only is gripped. Check that ⅓ of the shank length is visible below the chuck jaws. o Secure the drill firmly -then remove the chuck key. o If the drill does not run true -remove it and check if the shank is scored or the drill is bent (if a small size). 3. SETTING UP THE WORKPIECE (into a machine vice) o Ensure the vice is clean and free of metal shavings (swarf). o Lower (or raise) the table to provide clearance below the drill. o If you are to drill an open/through hole then place a suitable sized piece of flat timber into the vice to sit below the work piece. o Place the work piece into the vice and secure it. o Level the work piece either with a spirit level or by squaring it against the drill, using an engineer's square. NB.: On tilting table models ensure that the table is set to 0 (zero). o Secure the work piece firmly once it has been levelled. o Raise the table to bring the work piece surface a few millimetres below the point of the drill. o Manoeuvre the table, or the vice, or both, until the drill aligns exactly onto the centre punch mark (pull down operating handle to establish this). o Firmly secure all locks and vice mountings. 4. SETTING SPEEDS AND DEPTH CONTROL o If material is to be drilled through bring point down to contact work piece then set the depth control to approximately 5 mm more than material thickness. o On blind holes, set depth to specified amount. o With the aid of a chart establish the drill rotational speed with consideration to: a) The type of material being drilled. b) The diameter of the drill. c) The type of drill. (e.g. H.S.S.) (Refer to SOMTA User Guide - Drills, Reamers, Taps pages 12 - 17) o Set the appropriate spindle speed on your machine according to the operator's manual. Safety Notes: On belt/pulley drive models always ISOLATE THE POWER SUPPLY before effecting belt position changes. 5. DRILLING OPERATION o Wear suitable eye protection. Back to Table of Contents 7 o Start the machine and bring the drill into contact with work piece.
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