I build quite a few driveshafts and thought I would share a simple jig which helps with the welding.
This assumes you have a lathe to cut the drive shaft you wish to assemble.

After the parts have been disassembled the tubing is beveled (thin tubing, so not much). The seam inside is removed for about 3/4". A short shaft is run through both yokes to aid in indexing the yokes. The tube is then heated, and the yoke is dropped in, usually easily, but keep a hammer close by to ensure it is seated.

These shafts are not balanced and are not to be compared with a pro built shaft built on a proper drive shaft balancing jig. Having said that, there are a fair number of cars running around here using them.

The jig is made of 5/8" rod. The copper is 3/4". The copper allows the shaft to roll with less tendency to stick. I use a little dielectric compound to make it roll even smoother (not necessary). The copper is hay wired to the support so that it doesn't lift during rolling. The ground is attached to the copper.

Clean the shaft well were it will be in contact with the copper and were it will be welded.

I like to use a pair of chain vice grips to roll the shaft. It makes it easier to get the shaft to turn more than 180 degrees in each set up. Carry the stinger cable over your shoulders.

Start by placing a tack opposite to where you are going to start. It makes it pretty comfortable to make the full rotation with only two starts.

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