LECTURES
Note.—In order to determine whether the student is obtaining the information desired it is sometimes thought fitting to give written examinations. These serve as an index as to what the student has learned and what he has not. They also let the instructor know whether he is making every point clear in his training.
The following questions fit in with each chapter or part thereof and are merely a suggestion for the instructor who has no course of training outlined. With one or two exceptions all answers to these questions may be found within the manual. There are a few misleading questions purposely inserted to see if the student is thinking for himself.
LECTURE NUMBER ONE
Subject—Apparatus
1. Name the different classes into which oxy-acetylene welding apparatus may be divided and explain the principles upon which this classification depends.
2. Illustrate by line sketches the various locations of the mixing chambers for the oxygen and acetylene gases in welding torches.
3. (a) Where is the logical location for the mixing chamber in welding torches employed in automobile and tractor repair work?
(b) Give reasons for so thinking.
4. How is the torch and the welding tips treated after repeated “flash-backs” have taken place?
5. Describe briefly the working principles of a regulator and illustrate with a simple sketch.
6. Explain the difference between high and low-pressure regulators.
7. (a) Can acetylene regulators be interchanged with oxygen regulators with perfect safety? Explain why.
(b) How is it possible, in majority of cases, to distinguish in a very simple manner, between oxygen and acetylene regulators, when no gauges are attached?
(c) Why does this difference exist?
8. (a) Why should all tension upon diaphragm springs be removed before admitting gas under pressure to the regulator?
(b) Can a regulator which has been abused in this manner be repaired?
(c) What can be employed as a fitting substitute for gallilith?
9. Explain why the high-pressure gauge on the acetylene regulator cannot be used as an index to the contents of the attached cylinder of gas in exactly the same manner as the oxygen high-pressure gauge.
10. Why is glycerine used as a substitute for oil when regrinding torch valve-seats with emery powder, and with lead-oxide in the caulking of leaky joints along the line?
LECTURE NUMBER TWO
Subject—Operation
1. (a) Under what pressure is oxygen gas received in the cylinders used commercially?
(b) Does this pressure vary to any great extent with changes in temperature?
2. (a) Under what pressure is acetylene gas received in the cylinders used commercially?
(b) Does this pressure vary to any great extent with changes in temperature?
3. (a) In setting-up apparatus for the first time, or in attaching regulators to new cylinders, what precaution should be observed regarding cross-bar on regulators before the gas is turned on?
(b) Where should the operator stand when turning on the gas?
4. (a) How much pressure should be placed on the oxygen hose, when the torch-valves are closed, before starting to operate with a medium-sized tip?
(b) How much pressure should be placed on the acetylene hose, when the torch-valves are closed, before starting to operate with a medium-sized tip?
5. (a) After both the oxygen and acetylene gases are in the line hoses as far as the torch, which valve on the torch is opened first in order to light?
(b) What would happen if the other torch-valve were opened first?
(c) What would likely occur if both valves were opened before torch was lighted?
6. (a) How is it possible, when lighting torch, to determine whether enough pressure is on the acetylene line without looking at gauge?
(b) How is it possible, in the case of oxygen pressure?
7. (a) What is meant by a neutral flame?
(b) How hot is a neutral oxy-acetylene flame?
(c) Is the temperature of a neutral flame the same whether large or small tip is used?
8. (a) If too much acetylene gas is used, how will the flame be affected?
(b) What action will this have on the weld?
9. (a) If too much oxygen gas is used, how will the flame be affected?
(b) What action will this have on the weld?
10. (a) Explain briefly how apparatus is shut-off, when not to be used for several hours or more.
(b) Why should particular care be taken to see that acetylene cylinders are tightly closed when empty?
(c) What action does oxygen have on oils and greases?
LECTURE NUMBER THREE
Subject—Welding of Cast Iron
(Part One)
1. (a) How is it possible to distinguish cast iron from such metals as malleable iron?
(b) From semi-cast iron?
(c) From cast steel?
2. (a) What kind metal is used in making “filler-rod” used in the welding of cast iron?
(b) What general rule can be laid down as to the relation of the metal in the “filler-rod” to the metal to be welded?
3. (a) What are the characteristics of good cast iron “filler-rods”?
(b) Can piston rings and other small scraps of cast iron be used successfully as “filler-rods”? Explain why.
4. (a) What is the purpose of a flux?
(b) Is a flux used in the welding of cast iron?
5. (a) Name one formula for making a cast-iron flux?
(b) How often is the flux applied, and by what means?
(c) In what condition are fluxes kept when not in use?
6. (a) How should the flame be held in the welding of all cast iron?
(b) When and how is the “filler-rod” added to the weld?
7. (a) Name the one principal cause of blow-holes and hard spots in the weld.
(b) Mention some of the others.
8. (a) When is it advisable to grind, or “V” out, the ends of the pieces to be welded?
(b) When is it not advisable?
9. (a) Does the application of heat cause contraction or expansion in metals?
(b) Are there any excepts to this rule? Name one.
10. (a) Were two cast-iron bars measuring 2 × 12 inches and ¹⁄₂-inch thick, to be welded, end to end, what precaution should be observed in laying out, if the finished job is to measure just 24 inches long?
(b) In what respect would this problem differ were the bars only 6 inches originally and the finished job to measure 12 inches overall?
(c) Is the action of the metal in the weld a constant, or a variable quantity depending upon the length of the bar in this problem?
LECTURE NUMBER FOUR
Subject—Welding of Cast Iron
(Part Two)
11. (a) How could a spoke, broken midway between the hub and rim, of a 24-inch, 4-spoke wheel (otherwise intact) be welded without preheating? (Use a sketch if necessary to make method clear.)
(b) If a wheel of like size were broken only in the rim, midway between spokes, explain procedure in welding without preheating.
(c) Same sized wheel, broken only in hub;—can weld be made without preheating? Give reasons for so thinking.
(d) Were breaks (a), (b) and (c) all present in same wheel, with rim fracture on opposite side of adjoining spoke from break in hub, should welding be started at rim or hub? Why?
12. (a) In the building up of broken or missing teeth in cast-iron gears, what procedure is necessary when no carbon blocks are available for forms?
(b) If certain carbon centers from dry cell batteries are obtainable how should they be treated before allowing molten metal to come in direct contact with them?
(c) What very important point must be uppermost in mind when dental work on gears is being done?
(d) Explain precautions taken in allowing work of this nature to cool.
13. (a) Realizing that hard spots occur in most welds executed by the new welder and having learned the cause of their presence and how to overcome them, would it not be possible to utilize this process for hardening parts which were subject to much wear and little strain? Explain procedure.
(b) Why is it necessary to preheat such pieces as the following before the weld is attempted; broken water-jackets on gas-engine cylinders, usually brought about by freezing, and holes or cracks in crank cases, caused by the loosening of a connection rod; when lugs on the same cylinder, the arms on the same crank case can be welded without preheating, and ofttimes without even dismantling the motor?
LECTURE NUMBER FIVE
Subject—Welding of Cast Iron
(Part Three)
14. Describe fully the manner in which two cast-iron bars measuring 1 × 6 inches and 24 inches long, are welded end to end, citing preparations, precautions, and the procedure and materials necessary to execute and carry the weld through to a cool state.
Note.—Both gases are in the line hoses as far as the welding torch.
LECTURE NUMBER SIX
Subject—Welding of Cast Iron
(Part Four)
15. (a) Are water jackets on cast-iron cylinder blocks welded in a cold, or a preheated condition?
(b) Is this true under all conditions?
(c) If a crack were found in the combustion head of a cylinder block and the entire water jacket and cylinder were cast in one, how should this job be prepared in order to make a successful weld?
(d) In welding a broken lug on the base of a cylinder block how should lug appear after weld is cold?
LECTURE NUMBER SEVEN
Subject—Equipment
1. Describe the operation, step by step, taken to set up an oxy-acetylene welding plant, from the assembling of the parts, right through, until a neutral welding flame is obtained. (If a sketch, with the gas cylinders and parts numbered 1, 2, 3, etc., will assist in making description clear, it may be used.)
2. (a) Is it desirable to have a planed metal, or a brick-top table for welding purposes?
(b) Explain why.
3. Outline and describe briefly, a simple method of building a popular type of welding table.
4. (a) What is the name and style of bricks used in the welding shop?
(b) Name at least three purposes for which these bricks are used.
5. (a) Why does an emery wheel play such an important part in the oxy-acetylene welding industry?
(b) Why is it desirable to have a flexible shaft attachment for the emery wheel, if possible?
(c) Name some of the important things a flexible shaft attachment is used for in the preparation and finishing of welds.
6. (a) In what kind of containers is retort cement purchased in the commercial world?
(b) Where is retort cement used in the welding shop?
(c) How does it differ from the ordinary clay or putty?
7. (a) Why should a blacksmith forge be added to the welding shop equipment if one is obtainable?
(b) What two important tasks is a forge used for in the welding shop?
8. (a) It is essential that several pails of water be located throughout the shop; why should this be necessary?
(b) Mention a few instances where water is required in the welding shop.
9. Explain fully why great care should be exercised in ventilating a shop where commercial welding is being done.
10. (a) Describe one simple method of constructing a flux box.
(b) What advantages has this type of container?
LECTURE NUMBER EIGHT
Subject—Repairs
1. What is the best method of locating a leak in either the oxygen or acetylene lines?
2. If a leak were found in a ground seat, how could it be stopped if the nut on the coupling had been screwed up as far as possible?
3. Name one method of attaching connections to hoses so that they will not blow off or pull off when pressure is applied.
4. How could either an oxygen or acetylene hose that had been burned or otherwise injured, be repaired to withstand the gas pressure?
5. How could regulator be operated if the cross-bar for applying pressure upon the diaphragm springs were lost?
6. (a) What procedure would be necessary to make connection if cylinder were supplied with an adaptor which would not fit the regulator connection and it could not be coupled up directly?
(b) Realizing that all cylinder connections about a regulator are generally supplied with a ¹⁄₄-inch taper pipe thread, why do all manufacturers solder them in?
7. Explain why oxygen high-pressure gauges are constructed with a loose back and a solid front.
8. (a) Where is the first place to seek trouble in a gauge if it leaks?
(b) Can such leaks be repaired?
(c) Describe method.
9. If either a high-or low-pressure gauge were injured beyond the repair state how could welding plant be kept in operation without it?
10. (a) What would be the trouble, in shutting off a welding plant, if there were a reading on the high-pressure gauge and none on the low-pressure gauge, after permitting gas to escape from the hose?
(b) How could the reading on this gauge be brought back to zero?
LECTURE NUMBER NINE
Subject—Steel Welding
(Part One)
1. (a) Is the welding of steel more or less difficult than cast iron?
(b) Explain why.
2. (a) Why is the choice of the welding tip so important when working on steel?
(b) What will result if the tip is too large?
(c) If too small?
3. (a) Why is the choice of a “filler-rod” of a correct size so important for steel welding?
(b) What will happen if the “filler-rod” is too large?
(c) If too small?
4. (a) What kind of a “filler-rod” is used in welding steel?
(b) Give a general rule covering relation of “filler-rod” to the metal being welded in all cases, but one or two.
(c) Name one exception.
5. (a) Is a flux (or scaling powder) necessary in welding steel?
(b) Explain why.
6. (a) How is the flame adjusted for steel welding?
(b) What kind of a flame is generally used in finishing steel work?
(c) Why is this done?
7. (a) How is the flame held when executing a steel weld?
(b) How is the “filler-rod” held when making a steel weld?
8. (a) Is it necessary to “V” out on steel the same as on cast iron?
(b) Explain why.
9. (a) Is a steel weld as strong as the original metal if not built up?
(b) Explain why.
10. (a) Is the same provision made for expansion and contraction on steel as on cast iron?
(b) Give reasons for so thinking.
LECTURE NUMBER TEN
Subject—Steel Welding
(Part Two)
11. (a) What is meant by a “crater” in steel welding?
(b) How are they removed from the weld?
12. (a) What are some methods and marks of distinguishing steel from other metals?
(b) How is cast steel distinguished from cast iron?
13. (a) Name some of the qualifications of a good “filler-rod” for mild steel welding.
(b) In what manner does the “filler-rod” differ for the alloyed and high-carbon steels?
14. (a) In bringing the neutral flame in contact with the metal on a steel weld, should the cone bend and spread on the surface, or just lick it?
(b) Explain why.
15. (a) What is the principal cause for hard spots in steel welds?
(b) What causes some of the others?
16. (a) Is it rolled steel or cast steel that does not expand when heated?
(b) Name one other metal that does not expand when heated.
17. (a) Why are welds more difficult on sheet iron and steel than on some of the heavier pieces?
(b) What can be used as a “filler-rod” on sheet metal work?
18. (a) What difficulty is generally encountered, when making a long weld like on a steel tank?
(b) How can this be overcome?
(c) Why do the open ends on sheet steel welds overlap in welding when same class of work on cast iron separates?
19. (a) What causes steel welds to carbonize?
(b) What usually causes a burnt steel weld?
20. Describe fully how a broken automobile frame can be welded and re-enforced to make it stronger than originally.
LECTURE NUMBER ELEVEN
Subject—Steel Welding
(Part Three)
21. (a) What kind of a “filler-rod” is used in welding cast steel?
(b) Is a flux used?
22. (a) What kind of a “filler-rod” is employed when welding cast iron to steel?
(b) What kind of a flux is used?
23. (a) Can springs be successfully welded?
(b) State reasons.
24. (a) Why are crank-shaft welds so hard to execute successfully?
(b) What kind of a “filler-rod” is used for best results on most crank-shafts?
(c) What points does the welder consider when deciding whether a weld of this nature is advisable?
25. (a) Briefly describe the method of building up crank-shaft bearings that have been worn down.
(b) What are some of the precautions taken in work of this kind?
26. (a) When automobile propeller shafts and rear axles break, it is generally adjoining the square end. Is it advisable to weld this short piece on?
(b) What is the correct procedure in a case of this kind?
27. (a) If a case-hardened ring-gear is to have its teeth built up or new ones added, how is it handled after welding?
(b) Should all case-hardened work be so treated after welding?
28. (a) In welding two pieces of metal, one of which is considerably lighter than the other, how is the flame held in order to bring both pieces to a fusion at the same time?
29. (a) If a steel weld were to break in the line of weld, how should it be prepared if it is to be rewelded?
(b) Does this procedure apply only to steel?
30. Were a hole 6 inches square in a sheet of steel to be welded up without preheating, what would be the approximate size of the patch necessary and how would it be prepared, in order to take care of the expansion and contraction strains?
LECTURE NUMBER TWELVE
Subject—Steel Welding
(Part Four)
31. (a) Why should a steel weld of any kind be executed as rapidly as possible?
(b) What will happen if steel is kept in a heated condition too long?
(c) Why should a change be in evidence under these conditions?
32. (a) Explain what is meant by a “dished” patch, for boiler or thin armor plate?
(b) Draw such a patch.
(c) How is a patch of this nature prepared?
33. (a) What is meant by a “corrugated” patch for boiler or thin armor plate?
(b) Sketch such a patch.
(c) How is this kind of a patch prepared?
34. (a) What advantages has a “corrugated” patch over one that is “dished”?
(b) Where are “corrugated” patches used extensively?
35. (a) How are boiler flues prepared for re-tipping?
(b) Sketch a simple jig for holding such pieces in place for welding.
36. (a) Describe how lengths of various sized pipe can be welded together end to end.
(b) What precautions are necessary when executing such welds?
37. (a) When welding large steel castings why is it almost always advisable to preheat the work?
(b) Why is preheating so necessary on vanadium and other alloyed steels?
38. Why is it desirable to chip out the sand and thin scale formations, in and around blow-holes in steel castings before filling in?
39. (a) Why do the majority of good welders bend their steel “filler-rods” at right angles about 6 inches from the end?
(b) Why isn’t this being done on cast iron?
40. (a) What advantage is there in making a vertical weld from the top down, rather than starting from the bottom and working up?
(b) In welding overhead why is it so important that the work be in a molten state before adding the “filler-rod”?
(c) In overhead welding, why doesn’t the metal drop when in a molten state?
LECTURE NUMBER THIRTEEN
Subject—Oxy-acetylene Cutting
1. Explain fully which parts of an oxy-acetylene cutting plant are different from a welding unit.
2. (a) If there is a difference in either of the regulators, mention which one it is.
(b) What is the difference?
(c) Why is it necessary?
3. (a) Is it possible to weld with a cutting torch?
(b) What precaution is necessary if this is done?
(c) Why isn’t this process used?
4. Explain how cutting can be done with the welding torch if necessary.
5. (a) In cutting by the oxy-acetylene process, which does the cutting, the oxygen jet or the neutral flame?
(b) What action has the oxygen jet on the metal?
(c) What part does the neutral flame play in cutting?
6. Can oxygen or acetylene under sufficient pressure be made to cut individually? Explain fully.
7. Why is it specially important that armored hose be used on the oxygen line when making heavy cuts?
(Give at least two reasons.)
8. (a) How is a cutting torch lighted? Describe in detail.
(b) How is cut started on metal?
(c) How is torch held in regard to metal being cut?
9. (a) Is it possible to successfully cut cast iron?
(b) Wrought iron?
(c) Cast steel?
(d) Rolled steel?
10. (a) Cutting can be done under water with ordinary cutting apparatus; why doesn’t the flame go out when submerged?
(b) What additional equipment is generally used in underwater cutting?
LECTURE NUMBER FOURTEEN
Subject—Brass Welding
1. Explain as fully as possible the chief characteristics of a good “filler-rod” for brass welding.
2. (a) Is a flux used in welding brass?
(b) What is one way of making a good flux for brass?
3. (a) What kind of a flame is used in brass welding?
(b) Why?
4. (a) In what position is the flame held in welding brass?
(b) How should the “filler-rod” be held?
5. (a) Is it advisable to “V” out or burn off the ends of brass work to be welded?
(b) Explain why.
6. (a) What causes the dense white fumes to appear when fusing brass?
(b) What is cause of brass welds being porous?
7. Why should brass work not be disturbed when red hot?
8. What is the most difficult part of brass welding as a whole?
9. Why are brass welds generally cooled in water as soon as fusion is completed?
10. Why is it difficult for the beginner to weld heavy pieces of brass?
LECTURE NUMBER FIFTEEN
Subject—Welding of Malleable Iron
1. (a) Can malleable iron be successfully welded?
(b) What is the most successful method of joining two pieces of malleable iron?
2. What are three methods of detecting malleable iron?
3. (a) What kind of “filler-rod” is used on malleable iron?
(b) Are “filler-rods” of malleable iron satisfactory?
(c) What kind of flux is used on malleable iron work?
4. (a) How is a malleable iron casting prepared for welding?
(b) How hot should work be, previous to adding “filler-rod”?
(c) What will occur if too much heat is applied?
5. (a) In what respect does the adjustment of the flame differ on malleable iron from that of cast iron and steel?
(b) How is the flame held in relation to the work?
(c) Does the flame come in direct contact with the “filler-rod”?
6. (a) Is more, or less, surface covered by the “filler-rod” on malleable iron than on cast iron?
(b) Why?
7. (a) How should malleable iron be cooled?
(b) Is this the same as in welding brass?
8. On what part of machinery does a welder generally expect to find malleable iron castings?
9. Explain carefully how a malleable iron automobile, axle or transmission, housing that has been cracked or broken, can be re-enforced so that it will be stronger than ever.
10. Describe very briefly how malleable iron is made and in what respect it differs from cast iron when cold, and also when under the influence of the oxy-acetylene flame.
LECTURE NUMBER SIXTEEN
Subject—Carbon Burning
1. (a) Explain what is meant by carbon burning.
(b) In what respect is it used extensively?
2. (a) Will oxygen gas burn alone or does it merely aid combustion?
(b) Will carbon in a free state burn?
3. (a) Why is it advisable to remove only the spark plugs and not the entire valve cap or “bonnet” when burning carbon in a gas engine?
(b) Can it be done either way?
4. (a) Does it make a difference if the carbon is hard and dry in the cylinder?
(b) What will help in such cases?
5. (a) If the cylinder is rather oily does this make a difference?
(b) Does the presence of oil aid or retard combustion?
6. (a) What precautions are necessary before carbon burning is attempted?
(b) How is asbestos paper used in carbon burning?
(c) Name a good substitute for asbestos paper when carbon burning.
7. (a) Is there any danger of warping the valves and overheating the cylinder and piston when burning carbon?
(b) What is the effect of carbon burning on aluminum pistons?
8. (a) What pressure is used on the oxygen line for carbon burning?
(b) Will carbon burning re-grind valves?
9. (a) How long should the burning be done?
(b) How often is carbon burning recommended for a gas engine?
(c) If there are any carbon particles or sand left in the cylinder after burning is done how are they removed?
10. Describe how the carbon is removed from a four-cylinder engine, paying particular attention to details such as lighting, which part of the head the torch is played on first, what does the burning and where the carbon goes.
LECTURE NUMBER SEVENTEEN
Subject—Preheating Agencies
1. (a) What is meant by preheating as applied to the oxy-acetylene welding industry?
(b) What are several fuels which can be used very successfully for preheating?
2. Name the three principal reasons why parts to be welded are generally preheated.
3. (a) Why is charcoal considered the best preheating agent for general welding?
(b) Why should it not be used to any great extent in closed rooms during the winter months?
(c) If used during the winter what precautions are observed?
4. (a) Mention two materials which are used extensively for building up ovens and doing the preheating.
(b) What kind of brick is used?
5. (a) How much should cast iron be preheated?
(b) Brass or bronze?
(c) Aluminum?
6. Sketch and describe how a temporary brick preheating oven should be built, giving all dimensions, such as: length, width and height and reasons for them.
7. Explain how a cylinder block with a broken water jacket is set up for preheating; how oven is built for charcoal fire; how fire is started; how block is protected while welding and how it is returned to a cold state.
8. (a) What precautions are necessary in setting up and preheating aluminum?
(b) If piece is to be turned while in the fire, what provision is made in building up oven?
9. In which cases is preheating absolutely necessary in order to make a satisfactory weld?
10. (a) Give a sketch showing a preheating torch for use on illuminating gas and compressed air, which can be constructed very easily.
(b) Why are preheating torches not popular for general welding?
(c) Where are they used in numbers?
LECTURE NUMBER EIGHTEEN
Subject—Aluminum Welding
(Part One)
1. (a) Is the welding of aluminum, more or less difficult than such metals as cast iron and steel?
(b) Explain why.
2. (a) Name the two methods of making aluminum welds.
(b) Can they be combined?
(c) Why?
3. (a) What kind of a “filler-rod” is used in welding aluminum?
(b) Is a flux used? Why?
4. (a) Is a cast or drawn “filler-rod” preferred?
(b) Name the two important metals which should be present and the percentage of each in the “filler-rod.”
5. (a) How should the flame be adjusted for aluminum welding?
(b) How is the flame held in relation to the work?
6. (a) How is the “filler-rod” added?
(b) In what respect does this differ from all other metals?
(c) Why can this be done?
7. (a) Name the principal characteristics of aluminum with regard to heat.
(b) What other metal acts in a similar manner?
8. (a) Is it necessary to “V” out aluminum for the same reasons as other metals?
(b) Explain why.
9. (a) Will an aluminum welding be as strong as the original?
(b) Give reasons.
10. (a) What kind of a tool is used to aid in making an aluminum weld by most welders?
(b) How is such a tool made?
LECTURE NUMBER NINETEEN
Subject—Aluminum Welding
(Part Two)
11. (a) What kind of files are used to finish aluminum welds?
(b) In what respect do they differ from the ordinary kind?
12. (a) In which hand is the welding torch held in aluminum work?
(b) In which, the “filler-rod”?
(c) The puddle stick?
13. (a) What materials are used to “back-up” aluminum work for preheating?
(b) Describe fully how aluminum is “backed-up” previous to preheating, in order to prevent the collapse of metal while welding.
14. (a) How quick does the heavy coating or aluminum oxide form on a clean hot piece of aluminum?
(b) Will the metal flow together when this oxide is present?
(c) How is it overcome?
15. (a) Is it advisable to weld aluminum from one side only or from both sides?
(b) Why?
16. In preheating aluminum with charcoal, what precautions are taken in setting up; in starting the fire; during the welding operation, and in cooling the piece?
17. (a) Are preheating torches played directly on aluminum work?
(b) What kind of an oven is used?
18. (a) Is it necessary to heat the whole of an aluminum crank-case if one part has to be preheated?
(b) Give reasons.
19. (a) Are clamps used to hold parts in place on preheated aluminum?
(b) Explain why.
20. When starting to weld a cold piece of aluminum, the flame is brought in contact with the work and held there much longer than on a similar size piece of steel before any apparent change occurs. How is this accounted for, knowing that aluminum has a much lower melting point that steel?
LECTURE NUMBER TWENTY
Subject—Aluminum Welding
(Part Three)
21. Explain fully why it is necessary to employ greater speed in the welding of aluminum than on any other metal?
22. (a) What is retort cement?
(b) How does it differ from ordinary clay?
(c) For what purpose is it used in aluminum welding?
23. (a) When performing an aluminum weld by the puddle system, is the welder dependent upon the flame, the “filler-rod” or the puddle stick, for the fusion of the metal?
(b) Give explanations.
24. (a) What method of welding is used when executing a vertical weld on aluminum?
(b) Why isn’t the other method used?
(c) Is the vertical welding of aluminum to be avoided?
25. (a) Can aluminum welds be made overhead?
(b) Explain why.
26. (a) Is the same method used on aluminum as in cast iron in welding from the closed end, toward the open?
(b) Is this procedure necessary on preheated work?
27. (a) If a suspension arm, of a “U” type, on an aluminum crank case were to break about 3 or 4 inches from the body of the case, could it be welded in place without dismantling the motor?
(b) Explain in detail how such an arm should be welded.
28. Due to the contraction and expansion, it is very difficult to have the bolt hole, in the end of an aluminum suspension arm that has been welded, return exactly to its former position. How is this difficulty provided for?
29. (a) Should a section of an aluminum crank case be missing, would it be advisable to build up a new part with the “filler-rod” or to cast a new part in a mold and then weld it in?
(b) Under what conditions should the above be done?
30. (a) If it were found that an aluminum crank case after being welded, had one corner about ¹⁄₈-inch lower than the rest of the case and it had not affected any of the bearings, could it still be reclaimed?
(b) Give procedure.