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ok it has been put on my plate to repair a thread in a part that has a thread in it already. They want me to pick it up and rethread mill it i dont think this is possible and if it is i have no clue how. Any tips suggestions etc. please feel free to tell me where to start or why it can't be done.
I have done thread repairs on turning but not on milling.
Creap up with the tool to the thread as close as possible and skim it just enough to see witch way you have to offset until you get full clean up on thread.
Dykem the thread before cutting.
Good luck
heavenlykid
I would say it would be a struggle to do it on a cnc mill, if the part has orientation as to how it was clamped/made when the thread was cut, then this would make it easier to do but still no a easy task, If you have a manual lathe, & the part can fit in a lathe, it is very easy to do
Offer to bore it out and fit a Helicoil - probably a more reliable approach
Ditto #4
Dick Z
been there before and most times it's a dead simple fix
you don't specify the diameter but I'm assuming that its too big to tap , so with that in mind , start by qualifying the hole center , move across one axis while the other stays in it's zero position , then eyeball till the threads mesh with the thread mill , then calculate a z start point accordingly . Patience is the key and a bit of blue can be helpful
Otherwise ditto to the helicoil or insert
Use your offsets.
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I would go with what derstap said. I will only add that you have to align the tool tip to center. you can do this by using an indicator and manually touch it to get the peak while manually rotating your spindle back and forth. then you can move the tool on 1 axis to position to align with the thread while the other axis is at 0. It could be a little tricky if the hole is blind and you don't have room to go beyond by at least 1 pitch, but you can also get the coordinates for the entry using trigonometry.
A practice cut in a piece of hardwood will help give confidence the program is correct.
Measure twice, cut once.
Thread Milling Slideshow by neilw20_2008 | Photobucket
or just the pictures..
http://s399.photobucket.com/user/nei...?sort=6&page=1