Holding threaded stems

[nickbe10]

A question for all the lathe and mill/turn guys from a mill guy.

Has anyone ever used a threaded collet to hold onto parts with a threaded stem and various features on the end such as clevises or bearing carriers?

I think we could increase our efficiency in our mill/turn dept. if we could cut the threaded stem on one spindle and pass it over to the other completely thus freeing up first spindle to start the next part while finishing simultaneously on the second spindle.

Or some other method of holding the stem without damaging the thread but holding firmly enough to machine stainless steel.

All/any suggestions welcome....

[mkd]

Brass collet on major diameter?

...or thread on op2

[Matthew Hajicek - Singularity]

Yes, you can cut the matching thread in the collet and hold the threads of the part with it.

[nickbe10]

Thanks for the replies gentlemen.

Unfortunately holding on to the "non-thread end" is even more complicated due to the widely differing geometries of the hundreds of p/ns we have.

And Matthew can we get really trick and do an automatic pass over by keeping track of our thread start angle depths when we make the collet?

There are also some parts that have a little bit of full conical surface before the other features start so capturing that would help a lot with rigidity.

We have done a lot of the larger clevises on the 4 axis mills and my experience there has been that the  greater the  difference in size of the stem diameter to the end features has the biggest effect on the rigidity of the system. So small diameter stem with large end feature causes more problems than when they are closer to the same size (diameter).

Any other observations, experience or opinions greatly appreciated.

[Matthew Hajicek - Singularity]

As long as your machine can synch the spindles accurately you can cut the subspindle collet to whatever shape you like to pass the part over.  The only complication I see is that if the thread is deeper than the closure travel of the collet you may need to thread the part into the collet before closing it.  Or cut the minor in the collet oversized so you don't have to.  If you like I could put you in touch with a Swiss expert I've worked with who knows all about this sort of thing.

[nickbe10]

Hi Matthew,

That would be excellent and much appreciated. What do you need from me to proceed...?

 

[Matthew Hajicek - Singularity]

PM sent.