Reversing leadscrew

[jlavery]

Hi,

Has anyone cut a reversing leadscrew on a cnc lathe with fanuc Control.

[Geof]

I haven't but when you are successful I would be interested in finding out how easy/difficult it is. I believe this can be done with G32.

[jlavery]

Hi Geof,

I have programmed our Mori Seiki using G32 keeping the tool in contact with the material at all times and it is looking good in trial cuts.
The thread is 30mm dia. 3mm wide X 3mm Deep 11 full pitches @ 14.6mm

G0 X32.0 Z-20.0 Start point
G32X30.0F14.6
X29.8 Z-180.6 End point(20.0 +160.3 (Length of 11 Pitches @ 14.6))
Z-20.0
X29.6 Z-180.6
Z-20.0
X29.4 Z-180.6
Z-20.0
---
---
---
---
G0 X40.0

We are having special tooling made as the helix angle has to be cleared on the right and left hand threads.
Will let you know how I get on.

[jlavery]

Hi Geof,

Managed to produce the reversing leadscrew after a lot of tool trails and program editing.

The G32 cycle worked very well on the Mori Seiki SL15 machine. The main problem was programming the correct start and end of the thread so that the nut would reverse smoothly, this produced a very lengthy program. I have attached Jpegs of the finished leadscrew.

[Geof]

Originally Posted by jlavery .... a very lengthy program....

I can believe that from what I have read about G32; I understand you have to long hand every little detail in the tool path.

Thanks for the post and pictures.

[macca22]

Yes with Nl 3000 using mill in xaxis started at zero degrees a metre long with 40 mm pitch8mm wide & 8mm deep Using Caxis then around 90 degrees on the same Z then back stopping at Z Zero90 degrees from the initial start.then back to start same C and zero. Also widened the 2 90 degree portions so nut can turn.

[Kevin Taylor]

What is the aplication for this screw ? Thank's Kevin

[macca22]

This was used for winding wire rope evenly on mining drill retrieval drum. Attached to chain drives and guides hence the large pitch. Also run at slow revs.