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The Home-Brew Spot Welder
A spot welder is a necessity for the production of a homemade gas turbine, unless you can accurately and easily TIG weld a LOT of very fine stainless steel, on the order of0.5 mm. Commercially produced spot welders have several things wrong with them... first, they are rather expensive, typically $250-$500 U.S. Secondly, the welding tips, where the actual fusionoccurs, are relatively thick, and difficult to squeak into tight crevices like the bottom of a combustion chamber. They are also mostly hand-held devices, which would make the spot-welding of small partschallenging. So I guess if I was welding up a bed frame, a commercial welder would suit, but not a 2" dia. combustion chamber.
Thus, the need for a custom spot welder. Desireable attributes are a highquality, repeatable weld, ease of use, and low cost.
All of the parts for this welder (except the transformer) are available from MSC. The transformer must be scrounged from an electronics/industrialsurplus outlet. Look for a BIG 115VAC transformer (700 Va or better) with the secondary windings on the OUTSIDE. Listed below are MSC parts numbers, and current prices.
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An overall viewof the completed welder. Plans were "created" on the spot, using knowledge gleaned from the internet on such a project. The basic concept is to find a big 115VAC transformer which has the secondarywindings as the outer layer. The secondary is carefully (but tediously) removed, and replaced with enough coils of #4 copper cable to create a secondary voltage of ~4 VAC. a DeStaco clamp is adaptedfor the upper arm, while the lower arm is fixed, but insulated.
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A closer view of the modified transformer. After the secondary was removed, there was enough room for 5 turns of #4 copper,insulated cable. You can use welding cable, or you can cannibalize the cable from a set of automobile battery jumpers. Be sure it is heavy #4, and flexible enough to wrap around the transformer.
I got...