From: jimkirk@news.uwyo.edu (Jim Kirkpatrick) Newsgroups: rec.crafts.metalworking Subject: FAQ part 2 of 7 Date: 1 Sep 94 10:13:28 MDT Organization: University of Wyoming - Laramie, WY This is the FAQ for rec.crafts.metalworking. It is in several pieces to keep the overall size of each part below the limits imposed by some news systems. This is part 2 of 7. Generally, units below are United States dollars, degrees Fahrenheit, and all the other silly backwards units we Americans still use. Sorry. The questions being answered in part 1: 0. Where is this FAQ kept, and where are archives of the newsgroup? 1. The original rec.crafts.metalworking charter. 2. The CLOCKS bitnet mailing list, and other related lists. 3. What are some good books and/or video tapes on metalworking? 4. Who makes good lathes/mills/etc? 5. Where do I buy a machine? 6. What are good magazines to subscribe to? The questions being answered in part 2: 7. Where might one take classes or get instruction? 8. Where can I get raw material for my projects? 9. Where can I get tools, drill bits, etc.? 10. What are some of the related professional/hobby associations? 11. How do I harden/temper metal? 12 How do I wire up this strange motor? 13. How do I deal with mail-order suppliers? 14. How to sharpen knives, chisels, and other tools? 15. Some safety reminders. 16. How do I drill round holes? 17. What's TIG and MIG? The questions being answered in part 3: 18. MIG welding technique. 19. Which MIG welder should I buy? 20. Books on welding. 21. Soldering/brazing topics. 22. What are bolt grades? 23. What is XYZ made of? The questions being answered in part 4: 24. How do I build a furnace or forge? 25. What is Damascus steel? 26. How do I repair/replace this old leather belt? 27. Can I use a drill press as a cheap vertical mill? The questions being answered in part 5: 28. What is involved in building a steam engine? 29. How do I anodize aluminum? 30. Rust! How do I deal with rust? The questions being answered in part 6: 31. Are there any machinery museums? 32. How do I cut metal? 33. What kind of oil should I use on my lathe/mill? The question being answered in part 7: 99. Names and addresses of publishers and suppliers (OK, so I got tired of re-numbering it every time a new question was added!) ------------------------------------------------------------------------------- 7. Where might one take classes or get instruction? This depends on several factors, mostly where you live. Good places to check out include community colleges (universities sometimes will have classes in metalworking, but perhaps only for already-enrolled students or faculty/staff). Sometimes a high school will offer night or weekend classes to the public, funding permitting. Also look for vocational/technical schools, and possibly even art schools since some metal sculpturing requires a firm background in welding. In a few cases there may be specialized schools in your area, so check your yellow pages or ask around. Some examples: John C. Campbell Folk School in Brasstown NC (800) 562-2440, Craft Center in Ripley WV. Some schools also offer room and board and/or campground hookups. 8. Where can I get raw material for my projects? The Yellow Pages are often a good place to start. Also, the advertisements in magazines like Home Shop Machinist. Another way is to go find your nearest junk yard and/or metal recycling business and scrounge around. Make friends with a machinist at the nearest mining operation and ask for their throwaway "scraps". Order from a supply company (see ads in the magazines, and/or the "names and addresses" section elsewhere in this FAQ). Sometimes you can discover a creative re-use. For example, buy a few old aluminum automotive pistons, perhaps from your junk yard or a garage that rebuilds engines. Cut off the top and clean it up on your lathe. Now you have a nice round blank to start some project with. Similar discoveries should be posted to the newsgroup! Some of the magazines have ads for small "garage" shops that produce specialized castings. 9. Where can I get tools, drill bits, etc.? Many of the places that sell equipment also sell tools but there are also outlets that only sell accessories such as lathe bits, drills, taps, and so on. Scan the "names and addresses" section elsewhere in this FAQ. 10. What are some of the related professional/hobby associations? ABANA - Artist Blacksmiths Association of North America PO Box 1181 Nashville, Indiana 47448 (812) 988-6919 Dues are $35 per year, which also includes their publication "The Anvil's Ring" (see earlier, magazines) 11. How do I harden/temper metal? This is a *huge* subject, and depends on the metal, and intended use. Most of the time, this question is asked regarding steel, so we'll give a brief description of that, based on an article in Home Shop Machinist (Sept/Oct 1991, "Heat Treating Basics" by Steve Acker). [Also thanks to Steve Gaudio (?) for his post of 18-Sep-1992, and clarification by Tim Eisele] Iron will, at common temperatures, organize itself into an atomic structure that is called "body centered cubic." This consists of overlapping cubes with an atom at each corner, and one more in the center of the cube. But above roughly 1400 degrees F there is a change in structure to "face centered cubic" and the central atoms migrate to the faces of the cubes. This latter form is not magnetic. Steel is basically iron with some carbon mixed in, though modern alloys have various other metals and substances as well. When steel is heated to the critical temperature (about 1400 degrees F), the iron will change to face centered, and the carbon atoms will migrate into the central position formerly occupied by an iron atom. This form of red-hot steel is called austentite. Since it is not magnetic, a magnet may be used to determine when the critical temperature has been reached (though the magnetism may be lost before the transition, so this is only approximate). Complete migration of the carbon atoms may take a minute or two. If you let this cool slowly, the iron atoms migrate back into the cube and force the carbon back out, resulting in soft steel called pearlite. If the sample was formerly hard, this softening process is called annealing. If you cool (quench) the sample suddenly by immersing it in oil or water, the carbon atoms are trapped, and the result is a very hard, brittle steel. Too brittle for most uses. The structure is now a body centered tetragonal form called martensite. So, the next step is to heat it back up, to between 200 and 800 degrees F or so, depending on the desired end hardness. This allows some of the hardness to relieved and is called tempering. The amount of tempering that is desirable depends on the final use. Cutting tools are very hard, knife blades less so because they must flex under use rather than break. Tempering is a trade-off between hardness and flexibility. Accurately measuring the tempering temperature is important. A nice, expensive thermostatically-controlled oven is great. Or, some special compounds can be applied that melt or change color at the right temp, such as Tempilstik and Tempilaq. If the steel is clean to start with, then you may notice that it goes through certain color changes as it heats up, with understandably vague descriptions such as "light straw" indicating about 440 degrees F, and purple=520. These colors are not incandescence colors, but are viewed in normal room light. The colors are due to types of surface oxidation that are temperature dependent. When quenching, it is often very important to avoid stirring a part because this will cool one side much more quickly than the other, and might cause warping. For knife blades, as an example, move it strictly up and down during the quench. Case hardening is a bit trickier, and involves heating the object in some sort of agent that promotes hardening at the surface. Liquid cyanide works well but should be out of the question for the home machinist. Luckily there are substitutes available from suppliers, one being called Kasenit, for example. Note that hardness is often measured using a "Rockwell C" scale, with 63 being very hard and 35 being fairly soft. A type of steel called "drill rod" is especially useful for home/hobby use. As its name implies, it is the type of steel used for drills, and is available is round or square form (square drills?). Drill rod is also very useful around the shop because it is usually made to very accurate dimensions. Some types of drill rod are formulated for hardening via heating then quenching in oil, while others are quenched in water. The difference is that water will cool more quickly because it's a good conductor (though it may also form a steam "jacket" that moderates this effect), while oil will cool more slowly. Since rapid cooling may warp a part, this could make a difference in the final product. There is also an "air hardening" steel, though it seems to be quite a bit more expensive than other steels. It has been reported, by way of example, that you can make springs out of hacksaw blades by annealing, bending, hardening, then tempering by heating to a "metallic blue" and quenching in oil. I suspect lots of experimenting may be in order before you get things just right. Remember the steel must be clean (no paint etc.) to see the colors. Quenching in oil may be a fire hazard. Take proper precautions, such as removing flammable materials from the area, wear proper clothing, and have an extinguisher handy. Even quenching in water presents the risk of scalding from steam or splattered water. As one newsgroup reader pointed out, not only are there a gerbillion alloys, but zillions of treatments to choose from, and this is just for steels. Other metals, like brass, can be hardened by "working" the metal, by bending, hammering, peening, etc. Brass is usually annealed with a quench, which is the opposite of steel. It's best to carefully research your particular project first, especially if it's something that is valuable. A recent book, "Simplified Tool Steel Heat Treatment and Selection Guide" by Bill Bryson, may be of some help. $31.95 from Bill Bryson, Dept. HSM, RR 1, Box 4243, Union, NH 03887. I purchased this, and was surprised to spend $32 on 100 pages of loose-leaf pages. The information is geared more towards the small commercial shop than the home shop, and thus deals with issues such as atmospheric control (using stainless-steel foil) and using accurate temperatures. In the home shop, we usually read about methods like "hit it with a torch then drop it in a bucket of oil." Bryson goes beyond this, discussing accurate methods that might be out of reach for some of us, but just barely. He also has a chapter on cryogenic treatment, that can also be used in the home shop via dry ice. Power Model Supply recently (December 1992) listed two small heat treating ovens in an HSM ad. 2000 degrees F, 4x4x4 inch $330, 6x6x6 $435. Write them for more info or see the ad. 12. How do I wire up this strange motor? (with thanks to Bill Brown) The following describes how to deal with an AC/DC "universal" motor that has 4 unmarked wires coming out. Be sure you don't have some other motor, such as a 3-phase unit. Other motors are covered in an FAQ for the newsgroup rec.woodworking. The FAQ postings (six of them) for rec.woodworking are normally posted around the first of each month, and possibly also posted to the newsgroup news.answers. I can't say how long *your* news system will choose to keep these around! Look for "Frequently Asked Questions about Electric Motors." Also, the "Electrical Wiring FAQ" may be of interest. The universal motor is called that because it can run on AC or DC. Older units might have been designed this way because very early power distribution had not settled on AC or DC, or with 50 or 60 cycles. Thus, such a motor could be used universally, in all locations provided the voltage was within reason. This still may be a concern with some on-site jobs feeding power tools from DC sources such as portable welding rigs. Another nice thing about these motors is that they are easily reversible. They are also easily speed-controlled, such as in hand drills, whereas induction motors prefer to run at or near synchronous speed. The first task is to determine which two wires go to the armature, and which go to the field winding. If you can't tell by examining where the wires go (or the nameplate), get an ohmmeter and connect it to the wires until you find two that show some continuity. Rotate the shaft slowly by hand and note if the resistance changes as you turn it. If it does, you probably have the armature, and the fluctuations are due to the brushes making and breaking contact with the commutator. The other winding (field coil) should show a steady resistance. Presuming you want the ability to reverse the motor, find a switch that can handle the rated current, in the double-pole-double-throw configuration with a center-off position. The suggested hook-up is (as usual, a bad ASCII graphic): +-------------------+ 1 | | 2 ----------FIELD-------o<--O o A 0 white \ / R \ / M V X A O / \ T L black / \ U T ----------------------o<--O o E S | | +-------------------+ NOTE: no connection at "X"; Include a green-wire frame ground if at all possible Avoid reversing the motor while it is moving in the "other" direction as this could severely stress the switch and motor (particularly the brushes). Move the switch to the center (off) position, and continue on to the other direction after the motor has stopped. Please, always be careful when dealing with electricity. If you don't feel comfortable and safe doing such a hook-up, find someone who can do it for you, or at least who can check what you're doing. 13. How do I deal with mail-order suppliers? The following suggestions were offered by Stu Friedberg -- Get the catalogs and know what you want. There are often many sizes, models, and sources of an "X", so you need to know which particular X when you write and especially when you call to place an order. Even the smallest industrial supply houses deal in tens of thousands of items, which means even very knowledgeable order-takers can't always give you the information you need over the phone. Reserve queries about details for stuff that you couldn't figure out for yourself. Many of the order takers are very helpful and knowledgeable. At *SOME* sources the order takers can actually go look in the stock bins, take a micrometer to measure a shaft diameter, etc. I have had people at three different companies do something like this for me. However, some companies have computerized centralized order taking at a location completely separate from their stocking locations, so don't *assume* people can tell you anything that's not written in the catalog. I've had one company tell me to just order a set of change gears and return them if I couldn't use them. This wasn't crazy, the order taker simply had no relevant information available. Get the catalogs and shop around. Very often there are *big* differences in price between identical items, and even more often one source will have a unique or slightly different item at an excellent price compared to the "standard" item. There are lots of reasons for this. I have seen 2 to 1 price ratios on things like shim stock (from the same manufacturer) and "can't twist" clamps (from different manufactures but of equal quality). Occasionally, you will find 10 to 1 price ratios on things like boxes of hose clamps. Great deals if you look around. If you can, examine a tool at a local store (where the prices may be higher) to see what the quality is like, before placing the order by mail or telephone. You can also learn a great deal by perusing the catalogs, both about tools in general, and about specific details of specific tools. There's seldom enough room in a catalog to print all the manufacturer's data, but different sources will select different stuff to print. I have many times used one company's catalog to select the precise thing I wanted, then bought it from another company because the price was better. Most suppliers ship quickly if they have a credit card authorization. If they don't ship within two working days on a routine basis, shop somewhere else in the future. One full working day is quite common. I have had only one bad incident in the 4 or 5 years I've been buying industrial stuff by telephone, and came through with no losses. A supply company (which entered bankruptcy proceedings just a little while ago, by the way) charged my credit card for the full amount of my order, didn't ship for a month, and was completely clueless as to when they would ship my order. That is intolerable, and protection against abuse like that is one good reason to use a credit card rather than sending a check. You don't need to sue to get your money back if the merchant doesn't come through. (If it's not obvious, I got my money back and started to throw out that company's catalogs as they arrived.) Some industrial suppliers don't do back orders because it slows things down. The stock pickers send what's in stock and mark out of stock items on the invoice. This may be a little different from retail mail order sources you've dealt with in the past. Contact them about what's in stock and when it's expected to be available. Be prepared to return an item. Having to return an item because it was misshipped, defective, or of unsatisfactory quality is *NOT* an indictment of the supplier. If you do enough shopping for industrial supplies, you will find that you have to do a partial return maybe 1 time in 5. Don't get mad; don't get upset. It's routine. Industrial supply and consumer retail have different expectations about quality control. When you return an item, follow instructions. Many, but not all, suppliers require you to contact them for a "return authorization" number, which you must write on the outside of the package. You should include a copy of the invoice in the package. This is *NOT* an opportunity for the supplier to screw you over. This is a routine matter, and most of them just ask you to note on the invoice what was wrong and if you want credit, a refund, an exchange for something else, or whatever. 14. How to sharpen knives, chisels, and other tools? This is actually a tricky subject, and beyond the scope of this FAQ. However, an excellent book on sharpening knives and similar tools is: The Razor Edge Book of Sharpening, by John Juranitch. 1985 by Warner Books, ISBN 0-446-38002-4, $12.50 This book can sometimes be found in the larger knife stores, such as frequently found in USA malls (e.g. Cutlery World). It is a bit biased in that John also sells sharpening equipment, but the techniques are fundamental and can be used with competitor's equipment such as Lansky's. Another source for the book is Knife World Books, (800) 828-7751 Ext 71. Sharpening drill bits has never seemed easy. If you have lots of money, Darex makes drill and mill sharpeners, and Glendo's Accu- Finish line addresses simpler cutting bits (and they even re-sell some Darex tools in conjunction with their grinders). Black and Decker reportedly make a decent drill sharpener (1/8" to 1/2") for around $250. Some of the magazines will print articles from time to time on sharpening, and/or building sharpening equipment. 15. The following text on safety was donated by Gary Preckshot: The forces involved in metalworking machinery are far higher than most people expect. You can either be struck by shrapnel or pulled into a machine by being caught by a moving part. There are several rules that reduce these hazards: a) Don't wear loose clothes, ties, unsecured braids, or jewelry. b) Turn off machines and *WAIT* for rundown before approaching the working area. You'll spend a lot more time in an ER than you'll ever save by jumping in right away. c) Don't snap chips using a shop towel. Use a brush or air. d) Don't mess with long chips curling off a turning. If you get build up, stop the machine and remove the chips wearing leather gloves and using pliers. e) Keep power transmission belts of any kind isolated and guarded. Flat leather belts are especially hazardous because they tend to be unguarded on crowned cone pulleys. If in doubt, add more clamps. If in doubt, chuck more deeply or use a collet. A turning that comes adrift can damage both the lathe and you. A workpiece that shifts can damage both the mill and you. Stuff gets hot when cut. Let it cool before picking it up. Metal cutting generally leaves a sharp burr. Break the edges with a file or a de-burring tool before you release the work for general handling. Don't let kids, wives, husbands, girlfriends, or boyfriends close to metalworking operations without training or close supervision. Chips are extremely sharp. Long, curled chips from lathe turnings are especially dangerous because kids, wives, husbands, girlfriends, or boyfriends see only how pretty they are. You can get a very deep cut by handling such chips with your hands. Have a system for removing and storing chips. Use it regularly. Use eye protection - ALWAYS. Beware of fascination. Metal cutting tools flash and glint as they spin. An unwary person may reach toward the pretty, shiny tool. This is no joke. It happens. Then you take a trip to the local ER. Don't watch welding without adequate dark glass filters. You can get a tan in 2 minutes and a burn in five on any exposed skin close to arc welding. It doesn't hurt for about 3 hours, but then it hurts for days. Cover up. Don't play with air. Not only can it inject chips (by blowing them) into your body, but it can inject oily air as well. Sometimes right through the skin. Air is no joke. In general, no horseplay in the shop. Banish anybody who can't understand this simple rule. This is one place where absolute dictatorship is better than democracy. Take your time. You'll save on rework time, machine repair, and medical costs. 16. How do I drill round holes? In May 1993 the following question was posted. This brought a lot of useful suggestions for a problem often seen ... Subject: I can't drill round holes I am trying to drill 1/4" holes in 3/32" mild steel with a H/S twist bit in a 12" Delta bench press. The holes are not round. They tend towards the triangular. The piece I am drilling has a 1 1/4" square cross section. The distortion is worst in the exit hole through the bottom of the member. What is going on? Is there anything I can do to correct the problem? Morgan Hall gave the following shot as to how a simple twist drill manages to create a non-circular hole: Hint -- look at the rotor and housing of a Mazda rotary engine You can model the working end of a drill bit as a single straight line of finite length. If you fix one end and try to rotate it, the opposite end of the line sweeps out an arc. (the drill flexes) After about 1/3 revolution, the stuck end breaks free and sweeps out another arc while the formerly free end sticks. With alternate ends sticking, then breaking free, the arcs will form a kind of polygon with arcs of radius equal to the drill's diameter. After the first cuts, the "corners" of the polygon tend to stop the sweeping cut for each drill flute. The most common I've seen is the triangular hole, but other polygons are definitely possible. I suspect that this occurrence is related to some sort of resonance in the drilling setup. The suggestions that followed may be useful to anyone trying to drill holes. Some of them may qualify as 'obvious' but they're still worth bearing in mind... * Ensure the drill is sharp. * Make sure the work is firmly clamped * Don't try and run the bit too fast for the drill size and work material. * Don't force the feed rate; as with *any* cutting process, let the cutter do the cutting. * Keep as much of the drill in the chuck as possible. The more flexibility there is in the drill, the more likely you are to have problems. * When drilling thin material, it is often useful to provide some form of backing clamped to the work. This has the added advantage of keeping the burrs to a minimum. * The drill tip may need to be ground to a different angle, depending on the material being worked. * An undersize pilot hole is often a good idea. If you are drilling using a mark made with a centre punch and the tip of the drill is larger than the mark, you are unlikely to get accurate placement. * Don't forget to use a cutting lubricant * The quality of the hole is only going to be as good as the machine you are using will allow. If the drill spindle is sloppy, there may be nothing you can do about it. As a final comment, if you really want a round, accurately sized hole, you are unlikely to get it with a twist drill. Drill undersize and use a reamer if it's important. 17. What's TIG and MIG? TIG - Tungsten Inert Gas A small torch with a tungsten electrode is used to make the arc inside an envelope of an inert gas, usually argon or some argon mixture. A filler rod is manually introduced to complete the weld. The resulting weld is very pretty and usually requires no further finish. It is used mostly for welding sheets of mild steel, stainless steel or aluminum. The better machines have a foot control and a high frequency arc starter. Any sizable stick welder can be retro-fitted to do TIG welding, but without the foot control. MIG - Metal Inert Gas MIG and wire feed are the same thing. In this process, a consumable wire electrode is fed from a spool to the torch where the weld occurs inside an envelop of pure carbon dioxide, pure argon or a mixture of both. The weld continues as long as the operator has the trigger depressed and there is something to weld. This process is very fast, easy to learn and results in fairly good looking (better with argon) and strong welds. Most production welding of mild steel is now done with MIG welding. There is no slag to chip, but there is a slight thin coating of a glassy material that probably should be wire brushed off before painting. MIG welding can be used for thin or thick materials and is commonly used on mild steel, stainless and aluminum. Some common features of MIG machines are spot welding and stitch welding of sheet metal. There is a special wire called flux core that can be used in a MIG welder without the shielding gas. This process leaves a slag coating that must be chipped off. For most people on this group there isn't much use for flux core, as it was developed to reduce cost for large- scale welding where the cost of Argon starts piling up. There are fairly cheap 120 volt MIG welders that will only weld thin sheet metal. A more practical 240 volt machine that will weld up to about .25 inch is about $1500-$2000 new, $800-$1200 used. The machine I have will do MIG welding and stick welding, but most are MIG only. A machine that will weld .25 inch in a single pass will still weld thicker materials with multiple passes.