Cogging

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05 Jun 2011 02:57 #10301 by alexr
Cogging was created by alexr
ok

Im trying to figure out what is the best strategy for removing "COGGING" in emc2.

Incase you are reading this post and do not know what cogging is, well its that annoying grating noise when using stepper motors at low speed.

ultimately i would like to beable to soft-start the motors acceleration and smoothen movement.

Does any one know how to do this? can you give a step by step guide.

I gather i will be mucking around with hal?!

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05 Jun 2011 03:10 #10302 by PCW
Replied by PCW on topic Re:Cogging
Higher microstep ratios in the step drive itself will eliminate the noise at the step rate (but make it harder to run fast if software step generation is used)

In my experience the noise pretty much disappears above 32 uSteps / Full step

If your drives can only do full or 1/2 stepping, I doubt there's much you can do from HAL, but there may be some mechanical changes that would damp the inevitable noise from the steps

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05 Jun 2011 03:11 #10303 by alexr
Replied by alexr on topic Re:Cogging
im looking in hal config

im already lost, im not sure what i should be attacking to smoothen drive frequencies (to reduce / stop cogging) and soft-start my motors.

reading through the manual right now to see how. if you know the way im listening!

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05 Jun 2011 12:05 - 05 Jun 2011 12:07 #10306 by BigJohnT
Replied by BigJohnT on topic Re:Cogging
That is a function of your drives and steppers not a software related item. Drives like the Gecko 203v start out at 10 micro steps and morph to single stepping and have an adjustment for where the transition takes place. Less costly drives are going to be noisy at some point...

So the only way to fix that is to purchase a drive like the 203v.

John
Last edit: 05 Jun 2011 12:07 by BigJohnT.

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05 Jun 2011 22:16 #10330 by alexr
Replied by alexr on topic Re:Cogging
I already have some G203v's (step/dir) @ 2amp running my lathe. now that you mention it big john they do run smoother.... even on full step! better tools better job i get it!

Anyways this isn't the point! What I am trying to do is configure emc2 to my machine to reduce time, heat, wear, and waste! and at the moment cogging is slowing down my machine and making the motors hot and noizey.

I know this can be done i just need to find some one who knows how.... so i can check what i have done against what they did.... and diagnose whats happening (brainstorm solutions even).


you know one day i will actually be able to help people! instead of asking for help all the time!

i can roll my own RTAI kernel, collect and install all dependencies and get them to work together and i can even install emc2!! (took me six months and just short of 100 posts all over the web) I can do something few people dare to try.

and here i am again walking up hill on the high road.....................

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