A torch and a bucket of water with a few rags is all you need.I learned alot from the crew that straightens bulkheads and decks in the shipyard .Those guys were like magic, they could take a steel deck 1" thick that was warped all to hell and make it flat as could be.but hey whatever works. If you are gonna make several, you might want to make a jig so that you could pre-tension the axle while you weld it so when it cools it is already straight.I do that when I make handrail or any other pipe structure . It's a must for alum. pipe struct. the heat makes it go nuts. All you do is take a piece of heavy steel channel 24 in. and a piece of heavy angle 24 in..You need to blow a hole big enough for 1" allthread to go through in the center of one flange of the channel. Then you weld a nut that fits your allthread on the hole.Weld something on one end of allthread to make a tee handle. What your makin is a big clamp , the allthread screws against the angle to push the pipe to the other side of the channel. you might want to put a piece of pipe big enough for allthread to get caught in on the center of angle , so the angle won't slip.Oh yeah you gotta cut a notch in the channel for your intersecting pipe , it will have to come down to the web like a big u shape, make the notch big enough to get a tig torch in there to weld the joint. They are a real time saver

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