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Author Topic: Lathe threading issue  (Read 904 times)

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Lathe threading issue
« on: April 22, 2018, 02:18:00 PM »
Hi
I been using Mach4 with Pokeys57CNC for my mill, but now that I been trying to get my lathe work with Pokeys57U with external IO for steppers and Mach4 I have some strange issues with threading. I use indexer with pokeys and it reads RPM fine. When I try to make threads (metric) with the canned cycles which is built in mach4 I can't get threads right at all.  If I example put 1.75 for pitch and let it run it will make 1mm threads. (actually whatever pitch I use it will always make the same 1mm pitch threads expect if I use pitches under 1mm then it makes threads with smaller pitch). Does anyone have any idea what could cause this? (oh and sorry for bad writing... I am quite tired as I did try to fix this all day)
Re: Lathe threading issue
« Reply #1 on: April 28, 2018, 11:22:07 PM »
Hi,
does the PoKeys 57U support lathe threading?

Craig
My wife left with my best friend...
     and I miss him!
Re: Lathe threading issue
« Reply #2 on: April 28, 2018, 11:47:35 PM »
Hi,
downloaded and read the manual, and yes it does support index threading.

I note that you say if you attempt to machine a thread with a pitch less than 1mm it works? If you do repeated cuts of the same thread does the spindle synchronise
such that the cut deepens the previous one?

Craig
My wife left with my best friend...
     and I miss him!
Re: Lathe threading issue
« Reply #3 on: April 28, 2018, 11:57:01 PM »
Hi,
can you post some examples of Gcode that did work and some that didn't?

Craig
My wife left with my best friend...
     and I miss him!
Re: Lathe threading issue
« Reply #4 on: April 29, 2018, 12:07:34 AM »
Hi,
the only thing I can think of is that the Z axis is not fast enough.

If I understand correctly the G32 move is a linear co-ordinated move between the spindle an the Z axis. If you specify a thread of 1.75mm pitch for example, and the
spindle is rotating at 500 rpm then the Z axis must travel at 875mm/min. Could it be that the Z axis can't go fast enough do to the motor speed limit or some fault
of either Mach4 or the plugin? According to the Mach Lathe Gcode Manual the feed rate override is ignored when G32 is in operation. Lets say for arguments sake that
it is in fact enacted and the Z axis can only travel 500mm/min with an effective thread pitch of 1mm.

Craig
My wife left with my best friend...
     and I miss him!