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Micro stepping confusion
« on: June 20, 2011, 08:41:17 PM »
I am trying to get my homebuilt 24X36 Aluminum CNC to run without losing steps but I can't seem to get a handle on it.  I am using Keling drivers KL-9082 (http://www.kelinginc.net/KL-9082.pdf) with keling NEMA 34 1200 oz-in Steppper Motors, 72V power supply, PMDX126 BOB and a smoothstepper.

 I can get my motors tuned to run great when I am jogging, however when I try and run a 2 1/2 D  file the motors stall at different times. If run a program that does the carving along the x axis and the steps over in Y lots of stalling, if I have the program run on a 45 degree angle where both X and Y are both turning it runs 100% better.

When I look at all of the different setting for the micro stepping I don't know what is the best one. What would give me the best reliable performance.   I am trying to get my max cutting speed to be around 100 IPM my motors jog at 300 IPM no problem. Am I just expecting to much? I have been working on this for a year now and still can't get the performance that I want. I have tried so many different settings I am lost.

I have attached a photo of the router if that helps.

Thanks for any help

Tom

Offline Tweakie.CNC

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Re: Micro stepping confusion
« Reply #1 on: June 21, 2011, 03:15:37 AM »
Nice looking machine you have there Tom.

I would be inclined to opt for 2000 steps per revolution as I am not convinced of any real benefit from going higher.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline RICH

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Re: Micro stepping confusion
« Reply #2 on: June 21, 2011, 06:45:37 AM »
Quote
different setting for the micro stepping I don't know what is the best one. What would give me the best reliable performance.

Anything past 10 will not give you any better resolution because of the  stepping resolution / positional accuracy of the motor.
For most reliable preformance you should use a kernal speed of 25K. You  can try higher kernel speeds but run the driver test.

RICH

Offline olf20

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Re: Micro stepping confusion
« Reply #3 on: June 21, 2011, 06:58:01 AM »
Another suggestion;
Try to reduce the acceleration on all axis by a
large amount. Check to see if everything runs
correctly. If so then increase the acceleration
in small steps till the machine has a problem.
Back the settings down 10% (fudge factor).
Sometimes what we think / want our machines
to do is different that what they will do.
Repeatability is the key.
olf20 / Bob
Mach3, Atlas Knee Mill, 4th Axis, VcarvePro, ESS, Super PID.
Been Heating with corn since 1998
Re: Micro stepping confusion
« Reply #4 on: June 21, 2011, 10:54:07 AM »
Thanks for the replys. I have set the Micro Stepping to 2000 re tuned the motors. I have the kernal speed at 35K The drive test ran good.  What are the best settings to have my smooth stepper at?  Also I ran the same test programs, if I run the toolpath on a 45 degree angle having the x and y move the machine runs great but if I run with the x axis running back and forth and the Y just doing the step over I get a lot of stalling of the x motor I just don't under stand why that would be happining.

Thanks Again,
Tom
Re: Micro stepping confusion
« Reply #5 on: June 21, 2011, 01:31:01 PM »
Have you tried running it on the parallel port rather than the SS?  On a screw driven machine that light running 1200oz/in motors, acceleration shouldn't be an issue at all.  My last router had a 400 pound gantry, was acme screw driven with 1200oz/in motors and I was running acceleration at around 80...and it would go way higher than that without stalling.

Also make sure your power supply is adequate. If it's not providing enough current, you will get stalling when two or more motors start running at the same time.
Re: Micro stepping confusion
« Reply #6 on: June 22, 2011, 10:50:09 AM »
I have not tried the parallel port, from all of the posts that I have read the smoothstepper give better reliability.  My power supply is 72V but I will check what the output is when all of the axis are running, that might be part of the issue.

Thanks,
Tom
Re: Micro stepping confusion
« Reply #7 on: June 22, 2011, 02:41:43 PM »
The USB interface is much more susceptible to noise than the PP.  We had nothing but trouble with the SmoothStepper, but that was on plasma machines.  It worked great when it worked, but it wasn't as reliable as the PP.  Even on our routers, it would lose connection now and then during a program run.
Solved Problem I think
« Reply #8 on: June 22, 2011, 05:25:42 PM »
I switched over to the Parallel Port and ran the same setup, same troubles.  But I think I have solved the problem. ;D  I lowered the amp output on my driver to the lowest setting to 2.8 Peak amps and the machine is running with no problems I can push the speeds way beyond what I could before.  My question is why with the lower amp setting is it working?  I thought that the more amps I push to the motor the more power I would have, but I must have been off in my thinking. Hopefully someone can shed some light on this for me.

Thanks,
Tom

Offline olf20

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Re: Micro stepping confusion
« Reply #9 on: June 22, 2011, 08:25:18 PM »
It would suggest that your power supply is under
sized. Not enough current capacity.
olf20 / Bob
Mach3, Atlas Knee Mill, 4th Axis, VcarvePro, ESS, Super PID.
Been Heating with corn since 1998