Question re G76 threading code

andypugh wrote: The tool should be perpendicular to the work axis, or the thread will be the wrong shape.

Ok thanks for that.

So using a 60' tool perpendicular Q would be 29.5'

Q can be anything you want. But some numbers will work better than others.

Lots of debate here: www.practicalmachinist.com/vb/general/se...read-cutting-278289/

andypugh wrote: Q can be anything you want. But some numbers will work better than others.

Lots of debate here: www.practicalmachinist.com/vb/general/se...read-cutting-278289/

Yes Andy that is a good read. BUT it is still not clear (to me at any rate) if it refers to manual threading or CNC If you have the tool perpendicular to the job does the Q setting at say 29.5 use that angle with_cnc ie does linuxcnc move the tool in a the Q setting.

I don't actually understand what you don't understand.

Q is a virtual compound slide angle. The thread forming tool necessarily has to be perpendicular to the work, or it won't form a thread.

andypugh wrote: I don't actually understand what you don't understand.

Q is a virtual compound slide angle. The thread forming tool necessarily has to be perpendicular to the work, or it won't form a thread.

Thank you for being so patient Andy You have just lit the light bulb for me. with the "Q is a virtual compound slide angle" I could not get my head around whether to physically set the compound on the slide to 29.5 or linuxcnc does it with the Q setting thus keep the physical compound at 0.

Thanks again.

I was getting confused because I have not seen a CNC lathe with a compound slide.

(I have converted two manual lathes and removed the compound in both cases to increase stiffness)