PMDX-107 connect to Colombo Spindle

[CNC Noob]

HELP!

 Have been retrofitting a machine and have been stuck on a problem for just WAY, WAY too long. Somewhere on this forum there are Q&As with Bob & Steve helping me while trying to connect my spindle back in the spring/summer. Tried to reply to it but I guess the topic is closed or something. So .... here goes again.

 Everything else is connected and working properly except for controlling the spindle speed am still in desperate need of help on that. Only thing I can think to do is rip everything out and start from scratch with fresh information.

Here is what I am running.

-  MACH 3 (latest rev)
-  ESS - Ethernet Smooth Stepper
-  PMDX-126
-  PMDX-107
-  A/C Servo drives on X,Y&Z (working)
-  GE/FUJI AF-300E$ spindle drive w/ 18,000 rpm 10hp colombo spindle.


I've been able to get my Mach3 setup pretty far along for someone who doesn't know the first thing about electronics, but please disregard that thought. I really need a remedial lesson in the simplest form.

Thinking the problem is the PMDX-107. But not sure. YES I did perform the spindle test/adjustment.
My spindle is wired and set according to the PMDX-107 Manual and all the software is set according to the AN002 addendum as far as I can tell. Have played with the numbers and pulley ratios etc, but it never seems to change things. All settings are back to original recommendations.

There has been NO changes to my spindle drive firmware since connected to the previous controller. As this is a retrofit, the spindle has worked properly on the old controller and have seen it run myself even at a fairly low RPM.

My problem is that the spindle will not run on my mach 3 setup at anything less than exactly 3600 rpm. It will go up to max RPM, but there does not seem to be any science to the RPM after 3600. And it appears to run high, not low.

 Don't know if I have wired something wrong, set something wrong in Mach, set something wrong in my ESS or should have put in some resistors or what???

Attached are some pics that may be relevant.

[Bob at PMDX]

There has been NO changes to my spindle drive firmware since connected to the previous controller. As this is a retrofit, the spindle has worked properly on the old controller and have seen it run myself even at a fairly low RPM.

My problem is that the spindle will not run on my mach 3 setup at anything less than exactly 3600 rpm. It will go up to max RPM, but there does not seem to be any science to the RPM after 3600. And it appears to run high, not low.

** EDIT ** 3600 RPM is 20%, not 2%.  Still, check the "Minimum PWM" field just in case & see next post **

Lets see, if the max RPM is 18000, then 3600 is 2% of that, which sounds like a likely value for the "Minimum PWM" setting.  Go to the Mach3 "Config" menu and select "Ports and Pins".  Then click on the "Spindle Setup" tab.  Look in the top center section called "Motor Control" for the "Minimum PWM" field.  This is shown on page 4 of our AN002 app note.  Our example has this set to 1%.  Try setting this to zero, then click "APPLY" and then "OK" and see if that allows you to get below 3600 RPM.

Bob

[Bob at PMDX]

When you ran the PMDX-107 self test/calibration, did the spindle reach full speed (18000 RPM or something close to that) after the first button press?  And did the spindle go to approximately 5400 RPM (30% of full speed) after the 2nd button press?

If you look at the "PWM" LED on the PMDX-107, it should get brighter with higher spindle speeds and dimmer with slower spindle speeds.  If you tell Mach3 to set the spindle speed at 3600 RPM (the lowest that you say you can get), and then command the spindle to something slower like 500 RPM, does the LED get dimmer than it was at 3600 RPM?  You may need 2 people for this test - one to look at the LED and one to enter the Mach3 commands.

My problem is that the spindle will not run on my mach 3 setup at anything less than exactly 3600 rpm. It will go up to max RPM, but there does not seem to be any science to the RPM after 3600. And it appears to run high, not low.

What exactly do you mean by "it appears to run high, not low"?

[CNC Noob]

Bob,

 Just got a chance to look at the machine settings and collect some data.

 What I have failed to mention before is that my machine is quite large and you are correct, I would need another person helping me to do the DIM to BRIGHT led check.  With that said, In setting up the machine with PMDX-107 initially I did the self test/calibration best I could without any help as well. I did expect to not have RPMs exactly correct until I was able to get some help and fine tune it. My min RPM problem does not appear to be caused by the trimpot unless you tell me otherwise.

However I'm assuming that the mal-adjusted trim pot setting is the cause of the following skewed selected speed to actual RPM which by the way is reading...

s3000  =  3621
S3100  =  3743
S3200  =  3863
S3300  =  3989
S3400  =  4107
S3500  =  4217
S4000  =  4839
S4500  =  5439
S5000  =  6048
S5500  =  6655
S6000  =  7263
...and so on to 18,000 rpm

But my main concern is the lower RPM which as an example is still running at any speed S25 thru S2900 = Spindle speed 3600 exactly.

Did check the "Minimum PWM field" it was set to 1, I set it to zero, no change, then set to higher numbers, still no change. So I set it back to zero.

 As my PWM appears to be running at 20% minimum, please look over my wiring in previous message and my attached picture of mach settings and my .XML file really close and see if anything jumps out at you. My spindle drive manual is also attached on previous message.
 Perhaps it simply needs to be wired differently than others or I made a stupid mistake somewhere along the way.

[Bob at PMDX]

The commanded RPM vs. measured RPM table that you gave me does indeed look like the PMDX-107 is not quite calibrated correctly.  The relationship between commanded and actual is linear:

   actual RPM = (commanded RPM * 1.2139) - 21.3838

So adjusting the PMDX-107 trim pot should get you closer to the commanded values.

I looked at your XML file and I see nothing in there that could cause this issue.  The spindle pulley range goes down to zero, so Mach3 should not be forcing low RPMs up to some minimum value.  Note that I am making educated guesses about some of the ESS config parameters because I don't know what the ESS plug-in does with them exactly.

See if you can get another person to help look at the PMDX-107's "PWM" LED as mentioned above.

And/or try this:

I think that the easiest next step is to try and verify what voltages the PMDX-107 is outputting for various commanded RPM values.  To do this you will need a DMM or volt meter.  For each commanded RPM, measure the voltage between the PMDX-107's AGnd and Aout terminals *or* at the VFD terminal 11 (gnd) and 12 (V in).

** WARNING ** DO NOT TOUCH THESE TERMINALS!!  While the relative voltages between these two terminals should be limited to 10V maximum, these terminals are floating relative to earth/chassis ground and may actually be floating at 120 or 240V above earth ground.

Try commanding RPMs of 1000, 2000, 3000, etc by 1000's up to at least 6000 RPM, and report back the measured voltages.

Bob

[CNC Noob]

Bob,

 Using the DMM reading from AGND and AOUT I was able to narrow problem down to my controller settings. There was a low limiter setting at 60hz that kept the minimum at 3600 rpm. Not sure if the previous controller was able to run at lower than 3600 with that set or it was adjusted inadvertently or defaulted, but I'm not complaining.

 Next question. Is it possible to run my spindle at a commanded rpm of say 15,000 THEN adjust the trimpot down to match exact speed while it is running to dial it in more precisely or does it not work that way or is that 'a no-no' safety-wise?

 Thank you for your help.

[Steve Stallings]

You can use the trimpot to precisely calibrate to 15000 RPM if desired. Keep in mind that the overall linearity of the PMDX-107 and the spindle driver will likely not be better than 5% so your calibration will be precise at only that one speed. Also the speed will vary with load. The spindle drive may or may not have compensation for this effect. Mach3 did have provision for closed loop spindle speed feedback but it has never worked properly. Mach3 also has a provision for a linearity correction for spindle speed. It does work if the linearity.dat table is edited by hand. The auto setting for the linearity correction table does not work on most systems due to timing issues in Windows.

[CNC Noob]

Is it best to just set trimpot at the 30% (2nd button press) ?

This is all good information thank you.

[Steve Stallings]

We normally tell people to set the pot to get the correct maximum speed.

If you are really concerned with speed, I suggest that you run a series of S words and create a table to see how it acts. Then if it is not acceptable, start playing with the linearity.dat file. Note, this file does not exist by default and one created by an automatic test run in Mach3 are usually horrible.