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I confess to being interested in this thread and out of my depth but I've had a though. Could you not buy an M12 stud and cut an M10 thread in one end, or is there not enough metal?
Very nice work! Jim(?)Using a die means you did not have to cut a thread relief at the crank end of the thread.Interesting that you could not get the die started at 12.0mm, but it worked at 11.85mm. 0.006" smaller diameter for us Yanks.Always fascinates me what a big difference a few thousands of an inch can make in metal work.I salute you from afar!
Thanks for the kind words!Jim
use to fear threading on a lathe till I worked in shops that had Hardinge lathes. So painless using a hardinge. Been watching this thread,glad to see you dived in . Just make sure your center is spot on for truing your crank assembled.
Just a heads up on cutting threads on the lathe. *If* your lathe can run in reverse, you can put the tool in upside down and run the threads toward the tailstock. No pins and needles making sure you stop just in time.
There is a gal Blondihacks who does lathe machining on tube. She has one covering machining threads in which she covers doing them in reverse to prevent a crash. She is an excellent teacher mainly covering the basics especially for noobies like me. Even experienced operators have good things to say about her. I will try to find the video and post a link.kkEdit: Here's the link. https://youtu.be/q7scadYptTI
Well after planning on drilling, tapping and fitting a stud I changed course, thought what have I got to loose trying to build up the crank, worst case I just grind off the attempted weld and threading and go with the original plan.four jaw chuck centered the piece with a dial indicator. Not the easiest piece to secure in the jaws, with the weight on the back of the web three jaws just reach the sides of the flywheel. I trued the face with a dial indicator as well and found the shaft is slightly bent, I can true the tip but the bearing contact surface is then out so I went for the mid length, I don't think I would use this piece given the slight bend (about 15 thousands +/-). I bet someone went to town with a hammer trying to get the flywheel off after tearing the puller threads out of the rotor.I welded and turned the extension a couple times, weld imperfections kept showing up until I got it as good as I canI threaded it with a die, 1st attempt not the best, re-welded it and turned it once again and used a new tap M12 x 1.25. I had turned the stud end to 11.85 mm before placing the die, could not get the die to start at 12.0 mm.The threads are pretty tight, it would have been better if the threads were lathe cut but I can't seem to figure out the gear box on my lathe, can't get the lead screw operation to reverse, needs some digging into.....I built up the threads an extra 10mm from the original good crank I have, setting the rotor over the shaft it seemed it could use more length on the threaded endIt will work, just not sure I would use the piece but it was worth the effort
Yes you can Chuck as Iím sure you have, but you need a damn solid cross slide to do so, because the force is lifting the slide instead of pushing down on the bed.But nothing ventured, nothing gained.
The instructions for many lathes include threading details. That would include gear changes for imperial and metric threading if your machine is capable. I never see anything about reversing the carriage for threading, just release the half nut and move it back and watch your thread dial for reengaging. That gear appears to have been damaged by someone trying to engage it under power. Sourcing a new one should be fairly easy once you identify it's specs. Or make one using your lathe and mill. That is what I do when one is not easily sourced.
HmmmmÖYou can tell a lot about a bloke by his fingernails.
You can tell I can be careless swinging a hammer! My split in half index finger nail has finally grown out, I slipped with a long punch, guess how much that hurt when the punch met the finger. Think dropping to floor.
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