Messages

1

General Mach Discussion / Re: Spindle problem... slowly decreases RPM until stop.

« on: March 01, 2015, 05:39:06 PM »

Also, can someone explain the spindle motor tuning settings, as they pertain to PWM spindles, better?  The Mach3 manual does not provide very thorough explanations, and I'm pretty lost.

1.  Steps Per:  What does this do?  (I know what it does for a stepper, but how about here?)  I've tried settings from 100 to 20,000, and all it seems to do is change how fast the spindle speeds up.  Smaller settings result in smaller speedup, so 200 takes like 2 minutes, and 10000 takes like 10 sec.  Does this have an effect on the problem posted above, where RPM never reaches the speed I set, or the voltage being less than max at full speed for the pulley?

2.  Velocity:  What does this mean for a spindle?  Does it affect maximum speed?  Nothing I change in here seems to affect anything obvious.  Also, sometimes Mach3 forcibly sets it to something I can't change, I'm guessing based on my Steps Per and Acceleration values.

3.  Acceleration:  What do I want to put here?  Obviously bigger numbers seem to result in faster acceleration, but how do I computer/know what it should be?  Is it related to Steps Per and/or Velocity?

4.  Step Pulse / Dir Pulse:  Do settings here have any effect on PWM spindles?  Changing them doesn't seem to have any effect.

2

General Mach Discussion / Re: Spindle problem... slowly decreases RPM until stop.

« on: March 01, 2015, 05:27:38 PM »

An external 5V power supply didn't change anything.

I did flip the Active Low for the spindle step pin back off, because speed was operating in reverse (higher setting got slower speeds).  I can get constant spindle RPM now, but it's way off "specified" value.

Some questions...

1.  When I set the speed to 2500, Mach3 fills in the "S-ov" field to 2500, and RPM gets something value that winds up to about 95%, such as 2377.  See attached picture.  What does "S-ov" mean?  Is this RPM value being off normal?  I have a pulley ratio of 1, so shouldn't it just be 2500?  Why does the RPM value ramp up, then stabilize?

2.  I checked everything, and the spindle is providing 5.01V, and getting back 3.58-3.70V at 2500 (of 2800 MAX) RPM.  This happens repeatably regardless of which of the two computers I hook to, and whether I use USB 5V or external 5V.  So it seems like it's happening on purpose.

3

General Mach Discussion / Re: Spindle problem... slowly decreases RPM until stop.

« on: February 28, 2015, 09:50:21 PM »

I emailed Greg, and he responded that he wouldn't be able to respond until Wednesday (4 days ago), and I haven't gotten a response to any of my emails after that.  I'm hoping he'll have something insightful, once he gets a chance to respond.

4

General Mach Discussion / Re: Spindle problem... slowly decreases RPM until stop.

« on: February 28, 2015, 07:07:39 PM »

The SS does not have it's own power supply.

I plugged it into another computer, this time a desktop instead of the regular laptop, and used the same Mach3 .XML profile.  The same thing happened, and is oddly still affected by the spindle's acceleration setting.

I also tried both the .24 and .30 USB drivers, and the 17F and 17FE Mach3 plugins.  Same results.

5

General Mach Discussion / Re: Spindle problem... slowly decreases RPM until stop.

« on: February 27, 2015, 12:54:03 AM »

It's a USB SmoothStepper, but yes, I could probably get another computer into the garage tomorrow and try it.

6

General Mach Discussion / Re: Spindle problem... slowly decreases RPM until stop.

« on: February 26, 2015, 11:53:51 PM »

Not really, I'd need an oscilloscope.

7

General Mach Discussion / Re: Spindle problem... slowly decreases RPM until stop.

« on: February 26, 2015, 11:32:51 PM »

I just checked, and the spindle controller supplies a solid 5.01V the whole time, it doesn't drop.  The G540 output voltage to control spindle speed drops slowly (e.g. 5.00V, 4.98V, 4.95V, 4.94V...).

So it looks like the spindle and spindle controller can be excluded as the cause.

8

General Mach Discussion / Re: Spindle problem... slowly decreases RPM until stop.

« on: February 26, 2015, 10:46:36 PM »

I can see the PWM feeding the G540, and it seems ok, but I don't have an oscilloscope to see what the PWM signal is doing.  The way I understand it, the G540 is looking at the duration of the PWM pulses, whatever percentage of the pulse cycle is high (say, 50%) it then makes an output voltage that is also that percentage of the input voltage (such as 2.5V is 50% of 5V input).

9

General Mach Discussion / Re: Spindle problem... slowly decreases RPM until stop.

« on: February 26, 2015, 07:59:37 PM »

I'm still going to try it, but now I'm skeptical it will work.  Anything that fixed it would need to explain why restarting Mach3 fixes the problem, and is the ONLY thing that fixes the problem, plus the acceleration issue.

Any problems in the the spindle, spindle controller, or G540 should be able to be fixed by restarting those, and unaffected by restarting Mach3.  That's obviously the opposite of what's happening.  That really only leaves the SmoothStepper USB, the SmoothStepper USB plugin for Mach3, and Mach3 itself.  Which of course is why I came to post on these forums in the first place.

10

General Mach Discussion / Re: Spindle problem... slowly decreases RPM until stop.

« on: February 26, 2015, 06:47:19 PM »

Good idea, I'll try that when I get home!