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Author Topic: Jerky Movement on combined X-Y Movmenet 3 Axis CNC Router  (Read 12696 times)

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Jerky Movement on combined X-Y Movmenet 3 Axis CNC Router
« on: June 13, 2011, 08:16:58 PM »
Gday Guys,

We had our Matcam (Multicam) machine upgraded by CNC Teknix recently and we are just working out some bugs,

We have found that using CV mode in Mach3, optimises the motion too much causing engraving to be cut-off, but exact stop mode causes jerky movement and inconsistant engraving (See attached .JPGs)

Setting the "turn off CV mode when angle >" setting (General settings) does help,

a setting of 5 degrees = jerky movement (like Exact stop mode)
A setting of 10 degrees = "reasonable movement" - but still inconsistent engraving (As per attached JPGS)
a setting of 15 degrees = smoother movement but the "diagonal" lines are "wavy" rather than straight.

Would anyone have any ideas on how to tweak this issue out please?

Cheers
Rob.

Offline Tweakie.CNC

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Re: Jerky Movement on combined X-Y Movmenet 3 Axis CNC Router
« Reply #1 on: June 14, 2011, 03:53:52 AM »
Hi Rob,

Curious one this.
I do a lot of laminate engraving and have never seen anything quite like it.
Because the effect is not so pronounced on the letter N where the diagonal is nearer to 45 degrees, I would suspect that the software you are using is at fault and the machine is only following the GCode it has been given.
If the individual letters were created to a higher resolution I suspect everything would be OK. Perhaps you could try the attached code (which was created using the Mach Write wizard) and report back on the result.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Jerky Movement on combined X-Y Movmenet 3 Axis CNC Router
« Reply #2 on: June 14, 2011, 05:19:18 PM »
Hi Tweakie!

Thanks heaps for your reply mate, All assistance is greatly appreciated!

I will give your file a go and let you know how it goes!

I'm using Vectric - VCarve pro. the files were programmed in Illustrator using "Arial" font, and then I filled that contour with a V-Carve profile with a D-Cutter.
I have attached a file that we cut that displayed the anomaly. We have been engraving smaller text and it is not *SO* bad but is still not perfect!

The thing that interests me is that this machine DID engrave well when it had the Matcam controller system, but since the upgrade by CNC Teknix we've got these little gremlins to get rid of!

Looking forward to getting this sorted out :)

Thanks again!
Rob.

Offline ger21

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Re: Jerky Movement on combined X-Y Movmenet 3 Axis CNC Router
« Reply #3 on: June 14, 2011, 05:32:01 PM »
Does the machine have steppers or servos? I can't believe that CV is causing those issues, as the M in "Motor Control" is made up of long straight moves, which CV would have no effect on.

If it has servos, I'm thinking it's a servo tuning issue.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Jerky Movement on combined X-Y Movmenet 3 Axis CNC Router
« Reply #4 on: June 14, 2011, 05:38:19 PM »
Hi Ger21,
The machine has been upgraded to Servo Drive by CNC Teknix.

We have done some "Basic" Tuning, But i think more needs to be done!
Pete from CNC Teknix is coming up as soon as he can, so hopefully he can sort this out for us :)

It seems to do fine on straight moves ( where 1 axis is moving only), but where 2 axis move together ( as in diagonal) it is "Steppy / Wavy"

I knocked the setting down from 15 degrees to 8 degrees and it has MARKEDLY improved this issue! (Enough to get away with the engraving, but not perfect!)

Thanks for your reply ger21!

Offline ger21

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Re: Jerky Movement on combined X-Y Movmenet 3 Axis CNC Router
« Reply #5 on: June 14, 2011, 06:12:08 PM »
Make sure all the other CV settings are off, both in general config, and the two on the settings page (distance and feedrate).
changing the CV angle setting should have no effect on those moves, as they are single lines of g-code.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html

Offline Hood

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Re: Jerky Movement on combined X-Y Movmenet 3 Axis CNC Router
« Reply #6 on: June 14, 2011, 06:19:14 PM »
Can you attach your xml please.
Hood
Re: Jerky Movement on combined X-Y Movmenet 3 Axis CNC Router
« Reply #7 on: June 14, 2011, 06:43:45 PM »
Hi Ger,
I'll check those settings, If it turn CV mode off completely the machine is very "steppy" (each line of code has a slight pause before the next begins, which is slow on the engraving as there are so many lines of code!)

Hi Hood,
Thanks for the reply, XML Attached!
(I think this is the correct XML file as we do use the Mach 3 Mill program. This file came straight from the \mach3\Directory)

Thanks again for your help Gentlemen!
Re: Jerky Movement on combined X-Y Movmenet 3 Axis CNC Router
« Reply #8 on: June 14, 2011, 06:44:51 PM »
OOOps! Forgot to add the file!

 ::)

Offline Hood

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Re: Jerky Movement on combined X-Y Movmenet 3 Axis CNC Router
« Reply #9 on: June 14, 2011, 06:49:12 PM »
Ok your motor tuning is too fast for the kernel you have, you will need 65KHz, hopefully your computer can handle that.
Hood