Set-up to weld around a cylinder

If it does not have to be light, I would look for some scrap tubing that would slip inside to keep it straight.

As far as rotating the part, I would look at the local Goodwill Stores for a barbeque rotisserie motor. To adjust the speed think about wrapping a cord around the part and then using the motor to pull the cord. With something to increase the size of the motor shaft, you could get the part to turn faster.

Dan

Use a sleeve inside the tube to keep it concentric and to provide a backer plate for the weld. You can 'v' out the weld joint to allow full depth weld in one pass (as long as it in the .120" wall catagory) If I don't have a suitable scrap piece laying around, I take some of the same stock, slit it lengthwise, shove it in and let it expand to fit. Also, make sure that any weld flash inside the tube is removed to get a tight fit with the sleeve.

Set it up in a 'V' block setup, this can be some 2x4 blocks with notches for a one off run. Have your able assistant wear a helmet, watch the arc, and slowly rotate the shaft to keep the weld puddle about 30 degrees from the top surface. This also allows the ground cable to be solidly attached to the tube but not get in the way of rotation.

The weld process WILL warp the tube, it always happens. Make your extensi> I have a small, light load-bearing shaft about 5' long and about 1"

In the pipe shop at a small shipyard I used to watch the pipe welders welding stuff like this. They had 4 rigid casters set up in pairs each sort of forming a V, so that the piece could roll smoothly, then they wound rope around it which went to a pedal. They would fit the pieces together and tack them solidly, then put the part in the jig and weld smoothly all the way around it. They didn't usually have problems with warping.

If you clamp your pieces to the inside of a piece of angle iron, with the ends separated about 1/16", and then tack in two places, and then remove the part and tack on the other side and then hammer the part straight, you can probably weld it up without a jig. Unless you are pretty good you won't make a perfect looking bead, so plan on sanding it afterwards just to get the worst of the lumps off. As others have mentioned, you can straighten the shaft afterwards in a press if you need to.

GWE

Thanks for the pointers. This will really help. Execution is up to me.

Frightening.

Vic Redlands, CA