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Offline Hood

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Re: thread problem
« Reply #10 on: January 15, 2009, 11:12:07 AM »
can you attach your code?
Hood

Offline zarzul

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Re: thread problem
« Reply #11 on: January 15, 2009, 11:25:37 AM »
Tubular,

Looks like you may have 2 problems,  maybe they are related.    Are you using a wizard for the Gcode?

The X moving looks like a taper or chamfer command in the threading Gcode command,  don't know how else the x would move during the cut passes.

The z pitch change is very puzzling.  I think I would maybe write a short gcode series to move the z 6 " at a slow feed rate towards the chuck then rapid back to the start and repeat 20 times.  Put a dial indicator on the chuck end
and watch to see if it comes to the right place each time.

Good luck!!

Arnie

Offline Hood

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Re: thread problem
« Reply #12 on: January 15, 2009, 11:43:06 AM »
Is the pitch actually changing, kind of looks even in the pics?
Hood
Re: thread problem
« Reply #13 on: January 15, 2009, 12:51:48 PM »
I'd say the pitch MUST be changing. If the X was moving + ONLY, the thread top would be getting THICKER...
Seems so anyway.
RC

Offline Hood

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Re: thread problem
« Reply #14 on: January 15, 2009, 01:26:42 PM »
Yes, you are right, brain dead today (even more than normal ) with rewiring the lathe and doing the PLC Ladder.
Hood
Re: thread problem
« Reply #15 on: January 15, 2009, 01:28:39 PM »
You need to get a smaller PLC...one that you don't need a ladder to work on.
RC

Offline Hood

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Re: thread problem
« Reply #16 on: January 15, 2009, 01:30:41 PM »
LOL, I would still need a ladder, I am a short arse :)
Hood

Offline RICH

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Re: thread problem
« Reply #17 on: January 15, 2009, 03:04:22 PM »
Just some thoughts:
- in config>ports& pins> spindle setup ? have you checked use spindle feedback in Sync Mode for using the index

I would try air cutting and also do just a g32 thread and see if all is good as suggested. If ok,  then try the g76 threading. At least this way it you can eliminate something.
RICH
Re: thread problem
« Reply #18 on: January 15, 2009, 10:50:46 PM »
ok still have this problem , here is wath i did today

- remove mach3 with all related files, folder and driver from pc
- download and install a fresh copy of ver 3.042.020 plus config
- ran driver test at 35 kHz, everything fine here
- removed the ball screw from the lathe and clean. i tough a chip in the ball nut might give an intermitent slow down on the z axis and damage the thread
- change the electronic gearing on the z axis drive from 10 to 4. this gives me 10 000 ppr, this limits the rapids to 210 ipm but thats fine for wath i do
- ran turn diag. cut a thread in the air, everything fine.
- when everything done, i cut a thread on a piece of scrap, and got a perfect thread

I then loaded a good shaft in the lathe... guess wath same problem!!
after cuting a few more on scrap shaft, i found that the x axis moving problem dissapear. from wath i can see when the thread is cutting, the first 4 or 5 cuts are ok, then on the next one it starts fine then somewhere along the cut, it looks like mach3 stop sending the pulse to the z axis for a breif moment, the axis gets behind a few thousand for the rest of the cut, then the process repeats over the 16 toal cuts!!
i've tried suggestion posted here and still at the same spot!!!

Offline Hood

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Re: thread problem
« Reply #19 on: January 16, 2009, 02:28:20 AM »
Have you run the Turn Diagnostics plugin?
Hood