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jog issue, please help
« on: September 27, 2011, 05:27:13 PM »
First time post,

Back Ground. CNC DIY router table 10ft x 4ft x 2.5ft using 34 steppers and ball screws with porter cable head. Mach3 software. Been using it for about 4 years typically at 100ipm. Need more speed so we upgraded to rack and pinion on all axis. (2 to1 belt reduction, 1" pitch dia and 8x micro step). Wow what a difference. Now able to see up to 1000ipm. System working smoothly and repeatable on all individual axis testing.

ISSUE: when I request more than one axis command the next command starts before the first one is finished.

example:

f500
x40
z1
z0

At approx 39" z starts to 1", at 40 " z is back to 0. x actually measures 40" and mach3 screen does show z starting up around 39" (may be lag not sure)
@ 100ipm i do not see this. may have always had the issue just never ran these speeds before.

Tried different accel speeds and kernel speeds no change.

thanks in advance for your help

Offline Hood

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Re: jog issue, please help
« Reply #1 on: September 27, 2011, 06:04:28 PM »
Do you get a message when you start Mach and press Reset?
Hod
Re: jog issue, please help
« Reply #2 on: September 27, 2011, 06:37:31 PM »
no message.

ran some more tests. works correctly with a G0 command but not with the G1 command

Frank

Offline Hood

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Re: jog issue, please help
« Reply #3 on: September 27, 2011, 06:48:35 PM »
Can you attach your xml and I will see if I can get the same issue here.
Hood
Re: jog issue, please help
« Reply #4 on: September 27, 2011, 07:08:47 PM »
Attached is the file

Thanks for your help!

Frank

Offline Hood

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Re: jog issue, please help
« Reply #5 on: September 27, 2011, 07:31:23 PM »
I am afraid it just seems to be a function of your relatively low acceleration in relation to your feedrate. I tried at a feed of 50 IPM and it worked fine, also tried at 500IPM in Exact Stop mode and it was fine. You may wish to try messing around with the CV angle setting on General Config page or if your machine can handle it use G61

Hood
Re: jog issue, please help
« Reply #6 on: September 28, 2011, 10:45:38 AM »
Hood, thanks for the input. I'll try what you mentioned.


Frank
Re: jog issue, please help
« Reply #7 on: September 28, 2011, 05:41:49 PM »
spent the day cutting. tried different accels, and exact stop mode. Both would solve the issue but cause other issues when cutting at high speeds.

Going to think about it for awhile.

Frank

Offline ger21

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Re: jog issue, please help
« Reply #8 on: September 28, 2011, 06:23:04 PM »
Your accel is too low. What your seeing is caused by CV mode. In order to maintain Constant Velocity, one axis has to start moving sooner than you'd like.
What is your accel actually set at. I'm guessing you need it to be at 50 or higher.

You can also play with some of the CV settings.
Gerry

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