Clearpath SDSK steps per inch

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24 Jul 2021 01:17 - 24 Jul 2021 01:30 #215724 by cwatson1982
Hi, I purchased a machine that was running Mach 3 and after converting my main machine to kflop/kanalog felt like playing with LinuxCNC on this one.

I have a 7i76e.

These motors are capable of accepting quadrature or step/dir input and are set for 6400 pulses per revolution (even though they can only actually position to 800 points per revolution). I have them set up/wired for quadrature input and the mesa stepgen type set to type 2. In the previous Mach 3 config which was using the motors in step/dir input mode, the steps per inch were set at 32512 for a 5mm pitch ball screw. In pncconf this is what I entered.

It was WAY off. 19" of machine travel was read as some fraction of that on the DRO's. I divided by 4 and that got me close but I don't understand why and it is still not quite right. 
Last edit: 24 Jul 2021 01:30 by cwatson1982.
The following user(s) said Thank You: rodw

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24 Jul 2021 02:48 #215728 by rodw
Replied by rodw on topic Clearpath SDSK steps per inch
Can you share your ini file? Sounds like you may have inadvertantly multiplied your steps per inch by the ball screw pitch or something,

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24 Jul 2021 02:58 #215729 by PCW
Replied by PCW on topic Clearpath SDSK steps per inch
The scale should be 130048 steps per inch
(this will be called STEP_SCALE in the .ini file)

Note that in mode 2 you should set all the step timings short
(say 100,100,100,100 ns)

Also AFAIKR Clearpath suggests not using differential wiring
so connect the 7I76E Step/dir connector +5 to the Clearpath
+ inputs and the 7I76E STEP- and DIR- to the clearpath -inputs
and leave the 7I76E +STEP/ and +DIR pins unconnected

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24 Jul 2021 13:45 #215776 by cwatson1982
I re-wired the connections for step/dir and changed the input mode on the motor this morning. Now all is good using the same step_scale, I e-mailed teknic about using quadrature mode and will see what they say as I am curious. Since it makes no functional difference for my uses I will just wire the rest up as step/dir. Thanks for the responses!

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