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Author Topic: crazy circles from an ARC PP on one machine, OK on another!  (Read 3400 times)

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crazy circles from an ARC PP on one machine, OK on another!
« on: October 30, 2008, 04:12:50 PM »
Hi Gang!

I've got a perplexing problem with Vectric's V-carve.   I had it generate some Gcode using the G-code (ARCS) PP in Vcarve.   The gcode loads in my CNC machine showing huge concentric circles on most of the movements- circles that are far larger than my machine.

BUT!  When I loaded the job on my laptop to examine the G-code, it shows a nice normal toolpath.   Is there some setting in Mach that would affect the way it interprets arcs?

I discovered this because I've been having issues with the Gcode that Vcarve produces:  The cutter gradually climbs out of the job, apparantly by tiny fractions of an inch, until eventually the cutter isn't even in the material any more.   It has the appearance of lost steps, but Cut3d and PhotoVcarve don't have any issues, and slowing the Z axis way way down doesn't seem to solve it.  I tried encoding the part in each of the PPs that are compatible with mach and when I saw the ARC style PPs whirling circles all over the place I almost lost my mind!

I'm running on a Joe 2x4 hybrid using Keling 4030 drivers and 425oz motors.

Thanks gang!

Offline Graham Waterworth

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Re: crazy circles from an ARC PP on one machine, OK on another!
« Reply #1 on: October 30, 2008, 04:19:59 PM »
Try changing the IJ mode under general config.

Graham
Without engineers the world stops
Re: crazy circles from an ARC PP on one machine, OK on another!
« Reply #2 on: October 30, 2008, 04:28:54 PM »
Sweet!   Will do!   Thanks Graham!

crossing my fingers and heading home!

Cheers, Jim
Re: crazy circles from an ARC PP on one machine, OK on another!
« Reply #3 on: October 31, 2008, 03:41:06 PM »
Hey Gang!

Well, changing the IJ setting sure solved the giant circle problem, but I'm still wrestling with the disappearing part problem.

It looks like lost steps, but it happens every time I use V-carve pro, and never in any other program  (cut3d, photoVcarve, mach wizards)

Check this out:

anyone got any ideas?

Thanks!  -Jim



Re: crazy circles from an ARC PP on one machine, OK on another!
« Reply #4 on: October 31, 2008, 04:34:27 PM »
Jim,

   Have you looked in the G-code to see what in there is causing Z to creep like that?  Kinda smells like perhaps a post-processor bug.

Regards,
Ray L.
Regards,
Ray L.

Offline RICH

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Re: crazy circles from an ARC PP on one machine, OK on another!
« Reply #5 on: October 31, 2008, 05:38:36 PM »
JIM,
Looks like the spindle is creeping up or the cutter ( doubt it ) . When doing engraving work you need good  Z
axis repeatability. Also indicate out the surface and make sure it's flat. Styrafoam surfaces .......look for a flat spot
to try out the machining.
RICH
« Last Edit: October 31, 2008, 05:40:50 PM by RICH »
SOLVED! It was the Mach kernel speed!
« Reply #6 on: November 01, 2008, 11:38:13 AM »
Hi Guys!

Nah, it's not the bed.   This has been a long road troubleshooting this thing, and I've slowly eliminated mechanical problems and electronic problems.   I've been posting in the Joe 2006 CNC forum and the Vectric folk's forum simultaneously but I didn't keep up as well here in mach...

Anyhoo, long story short, I figured it out finally!

It was the Mach Kernel setting.   At some point I had bumped it up to 60,000 and forgotten about it.   Well, my athlon CNC computer handled 60,000 just fine until it came to those super-complicated text V-carving movements.   Apparantly that was just too much for it.   I set it back down to 25,000 and everything is hunkey dorey again!

Thanks everybody for all your help and suggestions!   Now, if you'll excuse me there is sawdust to be made!

Cheers, Jim

Offline RICH

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Re: crazy circles from an ARC PP on one machine, OK on another!
« Reply #7 on: November 01, 2008, 02:30:12 PM »
Glad you got it sorted out and better yet for the feed back on what was wrong.
I need all the help i can get. :)
RICH