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Author Topic: Spindle vs A-axis motor tuning, steps per unit?  (Read 6090 times)

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Re: Spindle vs A-axis motor tuning, steps per unit?
« Reply #10 on: January 19, 2014, 05:19:26 PM »
Quote
(so A axis tuning is working ok and spindle tuning steps per unit acts funny). When running at higher steps/s, the servo amp will smooth the rotation. With that slow movement, it really jumps, stays, jumps, stays..
It acts not funny, it acts how you set it up. 1RPM = 20 pulses per minute thats 1 puls every 3 seconds. The A axis acts the same, try
G0A0
G1A1F1
This behav is due to your poor resolution. You should increase it.

Alex

Offline simpson36

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Re: Spindle vs A-axis motor tuning, steps per unit?
« Reply #11 on: January 21, 2014, 11:52:15 AM »
I have a servo spindle (using step+dir for Granite devices VSD-E) which I have configured both as spindle and as A-axis, so they have both the same LPT port pins in Mach config. .

It works.

It has been a while since I have used a parallel port, but it seems you are saying that both the Spindle and the A axis are sharing the same physical pins. If that's correct, I can't imagine the thing is working at all unless by sheer coincidence.

Offline Hood

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Re: Spindle vs A-axis motor tuning, steps per unit?
« Reply #12 on: January 21, 2014, 01:23:50 PM »
His A zxis and spindle are one in the same and the parallel port driver does not care if you set the same pins or not for different axes. As long as both are not commanded at the same time it should be ok.
Prior to the Smoothstepper supporting SwapAxis() Greg allowed that to be done so that a few people could do tapping.
Hood
Re: Spindle vs A-axis motor tuning, steps per unit?
« Reply #13 on: January 22, 2014, 05:08:26 PM »
Quote
(so A axis tuning is working ok and spindle tuning steps per unit acts funny). When running at higher steps/s, the servo amp will smooth the rotation. With that slow movement, it really jumps, stays, jumps, stays..
It acts not funny, it acts how you set it up. 1RPM = 20 pulses per minute thats 1 puls every 3 seconds. The A axis acts the same, try
G0A0
G1A1F1
This behav is due to your poor resolution. You should increase it.
Alex

I was referring to "acting funny" as requiring a steps/unit value that is not corresponding to a real value in servo controller, unlike the A-axis which uses the real value. The 20steps/rev is plenty in my application and does not act funny at all in normal speeds as the servo controller motion planner smooths it just fine. Why use a higher steps/rev when that is ok and already gives plenty of steps/s at higher spinds RPMS.. I rather keeps the steps/s with parallel port as low as possible.

It was indeed the pulley maximum RPM value that caused it. Changing it to same value as maximum speed at motor tuning for spindle solved the issue.
Re: Spindle vs A-axis motor tuning, steps per unit?
« Reply #14 on: January 22, 2014, 05:13:51 PM »
I have a servo spindle (using step+dir for Granite devices VSD-E) which I have configured both as spindle and as A-axis, so they have both the same LPT port pins in Mach config. .

It works.
It has been a while since I have used a parallel port, but it seems you are saying that both the Spindle and the A axis are sharing the same physical pins. If that's correct, I can't imagine the thing is working at all unless by sheer coincidence.

Why not?

As long as I don't use the A-axis (servo-spindle with angular control) and spindle (as constant RPM spindle) at the same time, there is no problem. When I use the A-axis at ATC macro code, I make certain the spindle is not rotating. Outside the ATC macro, the A-axis is not used. Much more clear to me than using swapaxis to do the same.

The pins go the the servo amplifier running the brushed DC spindle servo motor with encoder. The servo amp doesn't know whether the steps come from A-axis or spindle rotating in MACH3. When using A-axis, I have to home the axis anyway to get initial angle correct - using spindle encoder index pulse as home switch.
Re: Spindle vs A-axis motor tuning, steps per unit?
« Reply #15 on: January 22, 2014, 05:17:48 PM »
I have not read the manual but the way I have always treated things in motor tuning is.
Steps/Unit
Units/minute
Units/s/s

So what I would say is set is
steps per unit to 20 as you are wanting one unit to be 1 revolution
set velocity to 3000 as you are wanting 3000 rpm
set accel to whatever you want but probably around about 20 for a start, that would be 20 revs/sec/sec so 3000rpm in 2.5 sec.

Set your spindle pulleys Max to 3000.

Hood

Thanks for your support. That pulley max speed setting solved the issue.