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Author Topic: PWM Spindle Calibration help. G540 & KBIC-120 DC Controller  (Read 8589 times)

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Re: PWM Spindle Calibration help. G540 & KBIC-120 DC Controller
« Reply #10 on: August 28, 2014, 02:41:19 PM »
Oops, my bad.  Most Dyna posts I've seen lately were about lathes & I made a wrong assumption.
Ah, that's ok Dickybird. :-)
The Dyna benchtop CNC mills are quite capable little machines. They weigh about 250lbs. I have the one I am working on running around 100IPM rapids but I will tune that down in Mach. No real need to have those sorts of rapids on such a machine.

I hope with all the advice and suggestions I can iron out my Spindle speed issue.
Re: PWM Spindle Calibration help. G540 & KBIC-120 DC Controller
« Reply #11 on: August 29, 2014, 02:33:01 PM »
Thanks to Jeff and Peter & Art with my KBIC-120 & Spindle Speed issues.

I made good progress:

I tested the G540 using my bench power supply at 10VDC. Connected to it and my DVM watching the output. Spindle pulley set to 0 min and 100 max.
Commanded S0-100 and the output tracked perfectly. 1V for each 10rpm commanded.

Set the KBIC-120 min pot to 0
Set the KBIC-120 max pot to max
I have a Hall Effect sensor on the spindle pulley.

I set the belt on a pulley in groove 3.
Set Pulley config to min0 and max 100
Using the KBIC's Pot inputs, P1 & P3 for power and P2 for speed signal input. Still connected to the SPDT for LOCAL or MACH control. Per Jeff Birt's drawing. (The DM2400 has this SPDT toggle switch feature as standard & original)

Did an S100 and noted the max spindle speed for pulley groove 2. Plugged that into the max setting for that pulley.
Did the same thing for pulley in groove 3

I think groove 1 is way too fast for the spindle. nearly 18k so I saw no real good use for that kind of RPM. On the Dyna DM2400 benchtop mill. (its max was originally 10k before the spindle DC speed control swap to the KBIC)

Tested speed spindle speed by calling various Swords. It was within several hundred RPM. Upper RPM was better than lower RPM with regards to tracking.

While the motor was running I wanted to load the spindle pulley, I did so by rubbing my finger on the pulley and the KBIC really sped up the pulley quite a bit.

I went into Mach Ports and Pins and checked

Retested. To my amazement, when I commanded a pulley speed, Mach adjusted the pulley speed to match within a few RPM with the feedback.
I really pushed on the spindle pulley and Mach adjusted the motor RPM to maintain that RPM within a few RPM.

SO, then, I decided what the hell, I will try CALIBRATE SPINDLE again.

I made sure I was on the correct pulley groove (2) and let SPINDLE CALIBRATE run. It ran fine and successfully seemed to calibrate my spindle.
I ran it again on pulley 3 and it ran successfully.

Now, when the rpm is called for Mach will set that RPM. When going to a slower RPM it is hunting a bit before it finally settles on the speed, about 2-3 seconds. So, my guess now is I need to learn to tweak the spindle PID settings.

While I can not use the chart on the headstock anymore because of the change to the KBIC-120, my RPM ranges are now:
Groove 2= 500 - 14000rpm
Groove 3= 250 - 7100rpm

And with the spindle feedback, it seems as though Mach will try and maintain the speed....in theory at least.

But I do need to familiarize myself with the PID to fine tune it. Spindle feedback seems to work fine.

So, here is where I need some advice on what to try or understand how the Spindle PID settings work in Mach and what to try to fine tune.


Thanks again everyone! Things are much better.