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Author Topic: Relationship of Velocity/Accel to G0...  (Read 9691 times)

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Offline ger21

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Re: Relationship of Velocity/Accel to G0...
« Reply #10 on: June 24, 2010, 06:08:35 PM »
What if you do G0 X500? You should get a blended speed over 600 with one axis moving. Dos it still do it?

If it does, try 35Khz mode. And get a PS2 mouse.
Gerry

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JointCAM Dovetail and Box Joint software
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Re: Relationship of Velocity/Accel to G0...
« Reply #11 on: June 24, 2010, 06:36:27 PM »
dang it I WANT TO PLAY WITH MY MOUSE   >:D  Seriously when I went back to a ps/2 mouse the motors were slightly better.  Again points to load/overhead....

Motors are rated at 6A/phase, yeah I've seen steppers get flaky when underdriven but really flaky if overdriven (current more so than voltage).

What is the default feedrate mode?  This is a simple gantry with A - angular unchecked and slaved to x.

Start installing these on the machine..... probably tonight  :)

Stan
Re: Relationship of Velocity/Accel to G0...
« Reply #12 on: June 24, 2010, 06:39:00 PM »
Sorry,  If I do a G0 X500 the motors complain a bit.  I have the feed rate override set to try to keep the G0 from running off the highend, otherwise the motors are going to complain big time..

Even if I reduce both velocity and accel in the tuning dialog to a more reasonable 425ipm which I know they will run.

Stan

Offline ger21

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Re: Relationship of Velocity/Accel to G0...
« Reply #13 on: June 24, 2010, 07:45:56 PM »
So if you set the velocity in motor tuning to 425, and do a G0 X500, the motor will still stall? What's the accel set to?
Gerry

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

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Relationship of Velocity/Accel to G0...
« Reply #14 on: June 25, 2010, 07:24:43 AM »
maybe I didn't set the accel low enough... when velocity set to 425 and accel to 42 (10%) then G0 problem still occurs..

Now I have found that using the sliders and letting mach set the number near to desired is better than entering the number in the box.

Stan

Offline ger21

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Re: Relationship of Velocity/Accel to G0...
« Reply #15 on: June 25, 2010, 07:32:32 AM »
Try the accel at 20
Gerry

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

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Relationship of Velocity/Accel to G0...
« Reply #16 on: June 25, 2010, 05:41:19 PM »
I will give it a whirl when I get the motors mounted on the real machine.  I have now taken the control panel apart a bit to start the next phase of the project.

Stan
Re: Relationship of Velocity/Accel to G0...
« Reply #17 on: June 26, 2010, 08:49:17 PM »
Now that I have thought a bit more about the accel setting.....

This is missing the point....  The motors run VERY SMOOTHLY in the motor tuning dialog at 1000+IPM and accel at 100+ ips^2 but very roughly in the normal operation (esp. G0) of things....

I am trying to figure out why they would run smoothly under the motor tuning dialog and NOT SMOOTHLY elsewhere.  At this point the velocity and accel constants do not matter (not attach to a real machine....) except to give a context to the issue.  At this point, I could care less what the velocity/accel constants are.  BUT if I can only expect Mach to deliver 30% of performance in normal operations then I need to keep that in the back of my mind when I get to the real world.

This may be a good example of why I should consider a SmoothStepper and get off of the PP.

Stan

Offline ger21

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Re: Relationship of Velocity/Accel to G0...
« Reply #18 on: June 26, 2010, 11:28:47 PM »
You might want to try asking this on the Yahoo group. I may have seen an answer to this before, but don't remember. Art or Brian might have the answer.

On my PC, I get exactly the same performance in motor tuning and running g-code.
Gerry

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

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Relationship of Velocity/Accel to G0...
« Reply #19 on: June 27, 2010, 09:02:15 AM »
Cool, I will ask there as well...

Stan