Q's for chromolly tubing experts

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I'm trying to find a suitable replacement for my cnc plasma cutter x axis driveshaft. The shaft is solid 3/4" od x 49.5" long steel bar with 5/16" holes on both ends to fit the spur gears into. My problem is that this shaft is bent in three places. I measured .030" runnout from the middle of the shaft to the end . I intend to try to straighten this shaft first, but plan b would be to fab another shaft. My question is can 3/4" x .120 wall tubing be expected to hold zero runnout over a 50" or so length?
Reply:Originally Posted by Jrc347I'm trying to find a suitable replacement for my cnc plasma cutter x axis driveshaft. The shaft is solid 3/4" od x 49.5" long steel bar with 5/16" holes on both ends to fit the spur gears into. My problem is that this shaft is bent in three places. I measured .030" runnout from the middle of the shaft to the end . I intend to try to straighten this shaft first, but plan b would be to fab another shaft. My question is can 3/4" x .120 wall tubing be expected to hold zero runnout over a 50" or so length?
Reply:I would straighten the original shaft..You can do it with a torch..Put one end in a lathe..The other in the center or use a steady rest at the very end..Find the high spot with an indicator..Leave it set at the high spot..Take a torch (hot hot) and heat the high spot in just the spot!!You will see it bend even higherBut as it cools down it will be lower that when you started..May take a few times but I can get a shaft out .030 to run within .005 in a hour or so.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:As far as the tubing question..DOM should be straight from the get-goBUTMany times if its chained down in the back of the steel truck and most times it comes 20Feet..It will be out where the straps go..Sometimes alot.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Ok, thanks guys. I'm going to get a couple 8 foot sections and indicate them to pick the best section. Thanks again.