Re: [CAD_CAM_EDM_DRO] cnc lathe - threading - alternitive method?????

Russ Waters wrote:

>Hi to the group..... I need to pick your brain on this one!
>
>I would like to come up with a alternitive method of threading with a cnc lathe,,,,, not using a feedback system with conjuntion of the G33 code, but would it be possible to cordinate the spindle speed with the feedrate of the z axis to do threading? I think it could be done, has anyone tried this, or have a theory on how it could be done????
>
>

Yes, but....

The problem is that there will be no precise relation between the
spindle and
the Z axis feed, so the thread will be an APPROXIMATION of the desired
thread
pitch! If your spindle speed were held within 10%, then you'd get a
thread pitch
that was somewhere within 10%. So, for a 32 TPI pitch, you'd get
something within
29 and 35 TPI. IS that good enough? I suspect not, for most purposes.

Secondly, you would have no way to make multi-pass threads. Every
thread would
have to be cut in a single pass. Think you can cut an 8-TPI thread in
one pass?
Hmmm, I'd like to see your lathe!

So, these are the reasons why feedback is used.

Jon