Displayed Spindle Speed is Incorrect

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WVDualsport
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Displayed Spindle Speed is Incorrect

Post by WVDualsport »

I'm hoping this is a very simple Wizard setting or something to correct.

I have a converted PM-30. I always run the machine in the high rpm pully. PM lists the high pully as 1400 to 3000 rpm as delivered. I usually cut 6061 or wood, so I run it mostly wide open at 3000 RPM. I have noticed that when CNC 12 calls for spindle speed I get max rpm all the way down to just over 1200 rpm on screen. I have checked the actual spindle RPM with a Tachometer and it lines up with the Hall Effect sensor and OEM display.

I am running the Acorn analog output through a KBSI 240D board to provide the PM Spindle Controller with signal.
There appears to be a 2.2:1 to 2.4:1 ratio in RPM. For Example:

When I call (In CNC12) for 300 RMP I get 660 at the spindle
510 RPM I get 1127 at the spindle
900 RPM I get 2062 at the spindle
1095 RPM I get 2519 at the spindle
1200RPM I get 2880 at the spindle ( this is max RPM on a tachometer and the display)

Here are a few screen shots:

Wizard
https://drive.google.com/file/d/1dy19lF ... sp=sharing

CNC12 showing 1500 RPM Spindle capability at 100% potential output
https://drive.google.com/file/d/1tnkl2k ... sp=sharing

CNC12 showing 3000 RPM Spindle capability at 200% potential output
https://drive.google.com/file/d/1SKE2VV ... sp=sharing

This hasn't been an issue so far, but would certainly be the first time I waded into 4140 at 2x the proper speed. I could (for now) be mindful of this in CAM and adjust accordingly to get the output I wanted, but that is not a long term solution.

Thanks for any assistance!
Attachments
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lavrgs
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Re: Displayed Spindle Speed is Incorrect

Post by lavrgs »

Are you controlling the spindle with the 0-10 volt pins? Did you run the spindle bench test?
https://www.youtube.com/watch?v=LMZRuRkTn7c&t=259s
WVDualsport
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Re: Displayed Spindle Speed is Incorrect

Post by WVDualsport »

lavrgs wrote: Tue Nov 23, 2021 11:08 pm Are you controlling the spindle with the 0-10 volt pins? Did you run the spindle bench test?
https://www.youtube.com/watch?v=LMZRuRkTn7c&t=259s
The 10v output from the Acorn runs to the KBSI where is outputs 5V to the Spindle Encoder. I built this a couple years ago. I think I ran the bench test, but I am not 100% sure. The Wizard is told that high gear = 3000 RPM, CNC 12 displays 1500 rpm for 100% output, and I have a roughly 2x speed at the spindle compared to what CNC12 is calling for.
Dave_C
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Re: Displayed Spindle Speed is Incorrect

Post by Dave_C »

I am running the Acorn analog output through a KBSI 240D board to provide the PM Spindle Controller with signal.
There appears to be a 2.2:1 to 2.4:1 ratio in RPM. For Example:
Ok, the 0-10vdc output from Acorn and your settings in the wizard seem to be set right. What is the KBSI doing with that signal? Is it a one to one ratio, not likely!

Is there a way to "span" the KBSI so that the 0-10 input represents the 300 to 3000 RPM range?

Not knowing anything about the KBSI there is no way to help you fix this! It does not appear to be an issue with the acorn, the display readings or your encoder. The KBSI module is just spanning the output wrong, most likely it thinks it is working with a 0-5 vdc input so therefor 5 VDC gives you twice the speed you commanded.

Dave C
Grizzly G0678 Mill ,CNC conversion with Acorn. G4004G Lathe, Mach 3 conversion to Acorn.
WVDualsport
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Re: Displayed Spindle Speed is Incorrect

Post by WVDualsport »

Dave_C wrote: Wed Nov 24, 2021 10:31 am
I am running the Acorn analog output through a KBSI 240D board to provide the PM Spindle Controller with signal.
There appears to be a 2.2:1 to 2.4:1 ratio in RPM. For Example:
Ok, the 0-10vdc output from Acorn and your settings in the wizard seem to be set right. What is the KBSI doing with that signal? Is it a one to one ratio, not likely!

Is there a way to "span" the KBSI so that the 0-10 input represents the 300 to 3000 RPM range?

Not knowing anything about the KBSI there is no way to help you fix this! It does not appear to be an issue with the acorn, the display readings or your encoder. The KBSI module is just spanning the output wrong, most likely it thinks it is working with a 0-5 vdc input so therefor 5 VDC gives you twice the speed you commanded.

Dave C
The KBSI just converts the 10V Acorn signal to 5V that the Precision Matthews can accept.

I'm confused as to why the Wizard is set to 3000RPM at max spindle output, while CNC12 still clearly shows that 1500 RPM equal 100% output. Thoughts?
Dave_C
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Re: Displayed Spindle Speed is Incorrect

Post by Dave_C »

The KBSI just converts the 10V Acorn signal to 5V that the Precision Matthews can accept.

I'm confused as to why the Wizard is set to 3000RPM at max spindle output, while CNC12 still clearly shows that 1500 RPM equal 100% output. Thoughts?
So are you saying that the PM machine spindle drive takes 0-5 vdc for 0-3000 rpm?

Acorn, as you have it set in the wizard (it does not set these numbers, you do) thinks 0 vdc is 300 RPM and that 10 VDC is 3000 RPM. That is how it is spanned and at 50% you would get 1650 RPM which is half way between 300 and 3000 RPM.

So does the KBSI converter handle the ratio correctly and at 0 vdc input it should give you minimum speed and at 5 vdc the spindle would be at 3000 RPM.

So for that to work, the KBSI has to do this: 0VDC from acorn should make the KBSI output 0 vdc as well. Then when Acorn is has an output of 10vdc the KBSI should output 5vdc.

IF the KBSI is not doing that then the span setup is not correct in the KBSI.

Dave C.
Grizzly G0678 Mill ,CNC conversion with Acorn. G4004G Lathe, Mach 3 conversion to Acorn.
WVDualsport
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Re: Displayed Spindle Speed is Incorrect

Post by WVDualsport »

My last question was how, if the Wizard is set to understand that the spindle will turn 3000 RPM, does CNC12 only show (in the original post's attached photo) that it thinks the machine will max out at 1500 RPM?
Dave_C
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Re: Displayed Spindle Speed is Incorrect

Post by Dave_C »

My last question was how, if the Wizard is set to understand that the spindle will turn 3000 RPM, does CNC12 only show (in the original post's attached photo) that it thinks the machine will max out at 1500 RPM?
I'm not in the shop but I think the 100% you see in the second picture is what the manual command is if you take it out of auto and run the spindle speed with the + and - buttons. What is the gcode asking for when you see the 1500 on the screen. Is it asking for 750 rpm or 3000 rpm? Don't guess, look at the G-code and see what the S command is calling for.

Also, if you look at your first picture of the wizard settings, the last setting on that page ask if you want to limit the Acorn output to 0-5 volts instead of 0-10 volts. It is set to "NO" so that mean is will output 0-10 volts. If you need 0-5 volts, skip the conversion module and just let Acorn output the 0-5 vdc the PM needs.

Dave C.
Grizzly G0678 Mill ,CNC conversion with Acorn. G4004G Lathe, Mach 3 conversion to Acorn.
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Re: Displayed Spindle Speed is Incorrect

Post by WVDualsport »

There was no program loaded when I took the picture. It would just work that way with MDI, or to run it manually with the pendant.
Dave_C
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Re: Displayed Spindle Speed is Incorrect

Post by Dave_C »

There was no program loaded when I took the picture. It would just work that way with MDI, or to run it manually with the pendant.
Try this since you say you are in MDI:

In MDI type each one of these commands and record the results.

M3 S1500 and what does it read on the encoder readout and take a voltage reading on the Acorn output. It should be 5 vdc!

Then M3 S300 and what does it read? Voltage should be 0 vdc

Then M3 and S3000 and what does it do? Voltage should be 10 vdc.

IF all that checks out we can more forward, if not, post the speeds and voltages you got for each test.

You did say that the encoder readout is the actual spindle RPM, checked with a photo tach?

Dave C.
Grizzly G0678 Mill ,CNC conversion with Acorn. G4004G Lathe, Mach 3 conversion to Acorn.
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