# How to calculate max velocity Mesa card can handle

31 May 2020 23:26 #169589
I have a more technical question.

My setup
Mesa 6i25 card + 7i85s
1000w servo 5 motors in total on machine
Reducer is 8:1
Steplen is 5000

I know there is a way to calculate max velocity on each motor but I don't know how anymore.

Hope someone remembers the formula

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31 May 2020 23:41 #169593 by PCW
The maximum velocity of a step/dir system would be

Velocity is distance per second
steplen and stepspace are in nanoseconds

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31 May 2020 23:42 #169594
1 sec / 5000 nanosec
or
1sec / 5 microsec
or
1 sec / 0.005milisec
or
1 sec / 0.000005 sec
=200000
divide that by two as there is usually the same time for the step space, you would get 100000 pulses per second,
Since there is no info on the encoder, can not help any further.

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01 Jun 2020 00:08 - 01 Jun 2020 00:11 #169596
What information do you need extra? Which encoder the driver of the motors? Driver is leadshine EL5-D1000. I attached screenshot of specs

.

My system is rack and pinion only the z axis is lead screw.

Is this total pulses that I need to devide by number of Stepgens or is this capable pulses per stepgen
##### Attachments:
Last edit: 01 Jun 2020 00:11 by Stephanisk.

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01 Jun 2020 00:18 #169597 by PCW
Each stepgen is independent so the number of axis doesn't matter

Those drives will take up to 500 KHz pulse rates so you can go much shorter than
5000 ns pulse width

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01 Jun 2020 00:25 - 01 Jun 2020 00:36 #169598
I looked in my ini files. Actually steplen is set at 2500 and stepscale is set to 500.

Stepscale means 500 pulses for 1mm of lineair motion correct?

Hope this helps to calculate max velocity and that I understand it again.

Could my steplen be set lower than this?
Last edit: 01 Jun 2020 00:36 by Stephanisk.

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01 Jun 2020 00:59 #169601 by PCW
Yes, if you have a stepscale of 500 pulses per mm and 2500/2500 steplength/stepspace
(200 KHz max) the maximum speed would be 400 mm/s (if not limited by maximum motor RPM lead-screw whip or other limits)

Typically you would set the axis limits to a bit less (25% is standard) than the stepgen limits

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01 Jun 2020 10:21 #169641
Thank you very much for your help in calculating. I think I understand now.

One more question though based on those specs can the steplen be lowered below 2500.

And how can you see this in the specs what steplen should be?

Regards,

Stephane

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01 Jun 2020 13:48 #169668 by PCW
The minimum steplength and stepspace for that drive are 1000 ns, though you
should in general not use minimum values but add some margin.

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