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Author Topic: Jumpy arcs and curves in Mach4  (Read 352 times)

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Jumpy arcs and curves in Mach4
« on: March 16, 2019, 08:53:37 PM »
New to the forum and this is my first post...
We just bought a new BOSS 5x10 CNC router with Mach4, HiConn Integra motion controller, and LeadShine drives/servo motors.
Factory support is a bit...limited.
It cuts straight lines no problem, but arcs, circles, and continuous arcs are very jerky and rough.
You can visibly watch and feel the gantry "lurch" in the Y axis, but the X axis appears very smooth.
We can rule out mechanical issues I think...the machine is new and has no binding or worn parts.
We can rule out the bit...we get the same issues with no material on the table and no bit in the spindle.
We can rule out feed speeds...we get the same results at 10ipm and 100ipm.
We are cutting poly/HDPE with a 3 flute upcut spiral by the way.
It's almost as if Mach4 is ignoring CV...it is most definitely turned on in the software.  But whether we change to the slider from 5 degrees to 189 degrees, we seem to see no change in cut quality.
The problem is also perfectly repeatable...we get the same lumps and bumps at the same points every time which would seem to rule out noise in the machine.  (We have a hefty earth ground on the machine right through the slab and 10' down)
Any ideas as to where else to look?
I'm attaching a copy of the G code file and some pics of both internal and external radii in 1/2" poly.  WE tried making 4 passes to see if that would improve cut quality, but no luck.
Thanks for your help!
Re: Jumpy arcs and curves in Mach4
« Reply #1 on: March 16, 2019, 09:16:08 PM »
Hi,
I don't have a solution but maybe an idea for a test that might narrow it down.

I'm wondering if the Y axis stepper driver is faulty or perhaps is executing full steps whereas the X axis is executing microsteps.

To test that idea can you change the Y and X axes? By this I mean that the step/dir signals from the nominal X axis
pins of the BoB be hooked to the Y axis driver and stepper. The X axis driver and stepper would be hooked to the current
nominal Y axis step/dir pins.

If this is feasible without permanently damaging circuit boards it represents a simple test that can aid the determination
of the  logical cause of the fault.

Craig
My wife left with my best friend...
     and I miss him!
Re: Jumpy arcs and curves in Mach4
« Reply #2 on: March 16, 2019, 09:21:48 PM »
Hmm...I can check into this but I'm still pretty sure this is a software issue.
Re: Jumpy arcs and curves in Mach4
« Reply #3 on: March 16, 2019, 09:25:58 PM »
Hi,

Quote
I'm still pretty sure this is a software issue

That may be so, in which case the test I've suggested will have a negative result, which will tell you as much as a positive
result. Currently 'Im pretty sure' isn't worth squat as evidence.

Craig
My wife left with my best friend...
     and I miss him!
Re: Jumpy arcs and curves in Mach4
« Reply #4 on: March 16, 2019, 09:29:01 PM »
10-4.  I understand.
I should mention however that there are 2 Y axis drives.  A master and slave.
The odds of both being faulty are pretty small.  If one were bad, we would have seen it show up with a lot of other symptoms including poor straight line cutting.
Re: Jumpy arcs and curves in Mach4
« Reply #5 on: March 16, 2019, 09:34:20 PM »
Hi,

Quote
The odds of both being faulty are pretty small.  If one were bad, we would have seen it show up with a lot of other symptoms including poor straight line cutting.

Very true....so don't bother with the test. Good luck.

Craig
My wife left with my best friend...
     and I miss him!
Re: Jumpy arcs and curves in Mach4
« Reply #6 on: March 16, 2019, 09:50:25 PM »
When your troubleshooting never rule Anything out. This is from a guy who made a lot of money fixing other peoples problems, and machines.  I am sure Craig has done a lot of the same.
Retired Master Electrician, Commercial HVAC/R Service and lots of Hobbys.
Re: Jumpy arcs and curves in Mach4
« Reply #7 on: March 16, 2019, 09:55:30 PM »
Hi,

Quote
This is from a guy who made a lot of money fixing other peoples problems, and machines.  I am sure Craig has done a lot of the same.

Made a living from it for forty years.

Craig
My wife left with my best friend...
     and I miss him!
Re: Jumpy arcs and curves in Mach4
« Reply #8 on: March 16, 2019, 09:59:09 PM »
Hi,

Quote
This is from a guy who made a lot of money fixing other peoples problems, and machines.  I am sure Craig has done a lot of the same.
   

Made a living from it for forty years.

Craig

  :)   I thought so.
« Last Edit: March 16, 2019, 10:00:40 PM by wmgeorge »
Retired Master Electrician, Commercial HVAC/R Service and lots of Hobbys.
Re: Jumpy arcs and curves in Mach4
« Reply #9 on: March 18, 2019, 11:05:34 AM »
Hello,

If you haven't already, you should check out the CV Wizards. Go to Wizard>Select Wizard and you'll see a few different options to help you get everything tuned up and running smoothly. They are fairly self-explanatory and have good instructions included in the wizards themselves.

Best wishes,
Bryanna
Newfangled Solutions Helpdesk: http://support.machsupport.com
YouTube Support Channel: https://www.youtube.com/c/MachSupportOfficial