Spindle speed display slowly increasing- Resolved with new VFD

[martyscncgarage]

Disconnect the analog wires from Acorn spindle output.
Connect a voltmeter set to DC to Acorn spindle analog output.
Go in Wizard. Set low motor rpm to 0.
Set high RPM to 10000
Write settings

Go to MDI
Call M3S1000, did you get 1vdc?
Call M3S5000, did you get 5vdc?
Call M3S10000, did you get 10vdc?

[kevincnc]

Okay it's like the Wizzard thinks it's set at 2000 max no matter what I enter and write. Am I entering it in the wrong place?

Here is what I get on the voltmeter with 10,000 RPM max (or anything)-
500 RPM- 2.5VDC
1000 RPM- 5VDC
1500 RPM- 7.5 VDC
2000+ RPM - 10 VDC

I can enter lower than 2000 max in the Wizzard and it acts the same.

Thanks for your help.

[eng199]

Just set the spindle speed in the software: <F1>, <F3>, <F1>.

The maximum spindle speed is 2200 in your last report.

I get the full RPM range with the manual Spindle Control on the VCP, I think the Acorn is not sending the correct analog voltage when it's commanded through MDI or a program.

If the full range works manually and not from a program, you are probably hitting a CSS limit. Check into parameter 116 and G50. Parameter 116 is 2000 in your report.

[kevincnc]

Just set the spindle speed in the software: <F1>, <F3>, <F1>.

The maximum spindle speed is 2200 in your last report.

I get the full RPM range with the manual Spindle Control on the VCP, I think the Acorn is not sending the correct analog voltage when it's commanded through MDI or a program.

If the full range works manually and not from a program, you are probably hitting a CSS limit. Check into parameter 116 and G50. Parameter 116 is 2000 in your report.

Thank you, I guess I should have read the manual in depth by now. I haven't run a CNC lathe since a single class 25 years ago so don't assume I know anything..

Setting parameter 116 to 2200 fixed the top speed problem, but something is still not right. It will go 2200 RPM if entered in MDI now, but it runs about 70 RPM too fast throughout the rest of the range. If I lower the max frequency on the VFD to 62.4 from 69.7, I only have a top speed of 1975. That can't be right.

Edit: I'll try again measuring voltage

[kevincnc]

It seems that what's happening is that the voltage is always about 1.2 VDC too high throughout the range which translates to about 70 RPM high. With min speed set to zero, the spindle still turns 70 RPM when feedrate override is all the way down.

Is there a parameter to control that voltage? I can see how changing the max VFD frequency a little to get 640 accurate would be okay for a small error, but not this.

[DannyB]

If the voltage is consistent, just use the bias settings on the teco.
See the bias and gain setting bn-05 to bn-10 in the manual

[martyscncgarage]

It seems that what's happening is that the voltage is always about 1.2 VDC too high throughout the range which translates to about 70 RPM high. With min speed set to zero, the spindle still turns 70 RPM when feedrate override is all the way down.

Is there a parameter to control that voltage? I can see how changing the max VFD frequency a little to get 640 accurate would be okay for a small error, but not this.

No, the analog spindle voltage output is not adjustable. 0-10VDC you have to work with the VFD.
I would not worry about being 70RPM off. There is no feedback to the VFD, nothing to tell it that the motor is running what is commanded.

And just for the record, I have never had to go into CNC12 parameters and make adjustments. Frankly, doing the test as I described has always worked.
Set wizard spindle RPM 0 low, 1000 or 10000 high, save it, go into MDI call out 1K increments and you should see the voltage change by 1 volt for each 100 or 1Krpm.

video I did sometime ago:
https://youtu.be/5B1EaeKjT9w

You might uninstall CNC12 completely, delete the directory, install a FRESH copy and re-key in your settings in the Wizard.

Marty

[Svin12]

Is there any luck with this? Mine is doing the same thing. But its just going to full rpm regardless what speed is called in the intercon gcode. S800 goes 1500. S1000 goes 1500. But when I call mdi s640 get 640. Call 500 get 510. Call 1000 get 998. It starts out going 1000rpm regardless then creeps up to 1500 over the next few seconds. On every gcode I make in intercon.

[martyscncgarage]

Is there any luck with this? Mine is doing the same thing. But its just going to full rpm regardless what speed is called in the intercom gcode. S800 goes 1500. S1000 goes 1500. But when I call mid s640 get 640. Call 500 get 510. Call 1000 get 998. It starts out going 1000rpm regardless then creeps up to 1500 over the next few seconds. On every gcode I make in intercon.

Did you run the spindle analog test show in the video before your post?
You need to make sure Acorn is putting out the correct Analog signals for the given speed called.
Disconnect the VFD and test at the Acorn terminals.

Have you tuned your VFD?
viewtopic.php?f=63&t=1650

Low end RPM is more important to get close (with in a few RPM) than it is for the top end.

Marty

[Svin12]

Just hooked up multi meter and it puts out 7.24v then just creeps up to 10.24v over the next few seconds. Any idea?