Stick welding is a huge PITA. The rods need to be kept in a heated dryer or they don't work chemically. The thing you're welding must be degreased and have no paint on it. It will bubble like nuts if there is grease or hydrogen in the weld area. Unfortunately, knuckleheads would use the ONLY wire brush in the place to clear grease off parts, meaning the brush was fully greased up and using it contaminated your parts. Idiots. Cleaning it was possible but never happened in the 2 years I was there. In the real world of welding, you MUST also preheat the steel AND brace it so it doesn't warp. That or pre-angle it so when it cools and contracts, it is where it needs to be, which is very difficult to estimate using a handheld tool and so many variables. And we were learning on soft steel, nothing special. Not hardened tool steels. You end up learning a lot of metallurgy and understand the real limits of welding being a small forging process, melting metals together in a small area rather than the whole thing. This works as long as the metals are similar, but different crystals react badly with each other, and metal is made of crystals when it cools into solid again. Hugely important to remember that. Also, with stick welding, there's spatter, drips, and the position you weld from matters a great deal. Flat is best. The others tend to run and make a mess.
MIG is easier, but tends to be the lowest quality welds due to lack of penetration. We were taught to make circles with it to improve penetration and make a stronger weld. Uses 3 times as much wire, which is often pretty expensive, but for a simple tool with only 3 real adjustments and hand held user, its the best you can manage. For assembly, this is one of the better choices. You can position, spot weld, verify the position is right, then finish the weld. It can be used in all positions pretty easily. I do recommend users of this have auto-dimming helmets and full safety gear but tig welders gloves. They give better feel. A friend was building a teardrop trailer with this method. Watch out for cracks. In a motor vehicle, the welder is legally liable if it fails on the road. This is a great reason to buy someone else's product rather than fabricate something for sale.
TIG is the best quality and cleanest welder with the lowest cost. You need argon gas, and the right tungsten rod, and the right fittings. We used 3/32nd tungsten and the fittings to make that work, we were using pretty thick 3/8 to 3/32nd steel and aluminum with this. Thinner metals need a thinner tungsten. If you're working with stainless, a 1/16th tungsten would be better, and the proper fittings to go with it. Keeps your weld temp really low, which reduces damage to the metal and the heat affected zone, which corrodes, is minimized. If you were building an exhaust for a car or motorcycle, this is how you'd do it. Not this kludged together stuff I keep seeing on BikeExif with inch wide stripes of iridescence, each of which can rust and probably will.
Another thing I learned about is Spalling. Carbon steel does this, badly, when it heats and cools. This is one of the reasons wood stoves are cast iron instead of steel plate. A steel plate stove needs a coating of cadmium I think. Something like that. Another option is stainless steel, which doesn't spall, but warps like crazy. Wood stoves are a good thing to buy from other people too. They are insured and have good reason not to burn down your house and negate your homeowners insurance.
Welding does give you all sorts of capabilities. In motorcycle building, welding up the frame from parts is something you can do, provided you are skilled enough. Practice a lot on scrap before you do the real thing. And ask yourself if the cost of a welder justifies itself when you can buy a frame used and clean it up, then mount all the parts and accessorize so nobody would have cared anyway? What makes the most sense?
Note I didn't talk about brazing, which is a related skill to welding, as brazing requires oxy acetylene gas setup and I don't think you should have that in your house. The above welders are safe to keep in your garage. MIG uses CO2 gas. TIG uses argon. Stick doesn't need gas at all. However, Acetylene is particularly dangerous as a sharp shock or slightly too high pressure in the line can make it explode. Exposure of the lit gas to grease also causes explosions. It's the preferred method for cutting thick steel and preheating parts for welding, and it's relatively cheap, however it is really dangerous and will greatly increase your homeowner's insurance. I suggest you use other methods or build a shed away from the house for its use so you don't get yourself into trouble.
There are other ways to cut steel, including a plasma cutter, which combines a TIG welder and high pressure air from an air compressor to generate 25,000 degrees and can cut up to 1/4 inch steel or stainless or aluminum. Hot knife through butter, basically. The parts degrade with use, so you have to have a good supply for them.
Good brands are Miller and Lincoln. They aren't cheap, but they aren't exhorbitant either. If you do opt to get something like this, take a class or two and find out if its for you. Its really too expensive for an untested hobby. And the best TIG welders have water cooling along the hose to the torch. Those which don't can overheat and melt. That gets expensive. You can do without if you use them only a few minutes at a time. There are guys whose work involves portable welders, like farmers and fence and piping repairmen. Most use a generator and carry their welder on a strap. Figure out what you NEED before you spend any money, and take some classes to see if you're any good at it. The realities of welding, and the low pay, are what put me off.
You can learn a lot about it on YouTube videos, however. A great deal. If it doesn't make you itch to try it for yourself, you don't need to spend the money.
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