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Max Velocity gets set at Ludicrous Speed

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20 Jun 2016 04:08 #76297 by thaelin
thaelin created the topic: Max Velocity gets set at Ludicrous Speed
Hey all:
Well have been doing a lot of reading here before I joined and then did more. I have the mill setup and running but the initial start sets Max Velocity at 300 which the steppers cannot keep up with. Jitter is around 18000 and set for 19000 half stepping at 6400 per inch and seems to do fine.
Just would like to know how to curb that velocity to around 15"/s as that is about the tops it can move.

Setup is HP slim 3ghz 2gram 750g can 4axis break out with m542t controllers to nema23 423oz/in steppers and a 36v 350w ps.

Mill its self is all hand built and in final stages.

attached is what I think you will ask for so added.

Thanks all thaelin
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20 Jun 2016 09:19 #76303 by andypugh
andypugh replied the topic: Max Velocity gets set at Ludicrous Speed
The values are in two places. You can either change the max velocity in stepconf, or manually edit the INI file.
To be honest, I would normally suggest accepting that Stepconf's work is done, and start editing INI and HAL directly.
However yo have not yet configured limit and home switches, so perhaps you should use stepconf.

The reason that this is an either/or is that Stepconf is write-only. It uses its own internal data to write HAL and INI and will over-write any changes that you make in those files.

The numbers in the INI file are 4.36 in/sec. To experiment you can change them in the INI and restart to see what works.This is probably a faster cycle that using Stepconf until you know the numbers you want.

In the INI, each axis has a section like this:


[AXIS_0]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 4.36580882353
MAX_ACCELERATION = 20.0
STEPGEN_MAXACCEL = 25.0
SCALE = 6400.0
FERROR = 0.05
MIN_FERROR = 0.01
MIN_LIMIT = -10.0
MAX_LIMIT = 10.0
HOME_OFFSET = 0.0

Just change the number higlighted in red to the inches/sec that you want.

(Incidentally, I am fairly sure that Stepconf asks you for the max velocity, rather than choosing it for you, but it is many years since I used stepconf)
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11 Nov 2016 19:45 #82703 by SenorAguas
SenorAguas replied the topic: Max Velocity gets set at Ludicrous Speed
One thing that tripped me up is that the stepconf asks you for max velocity in machine units/minute and the ini file is machine units per second.
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