[Joe2014]

I recently assembled a CNCRouterParts PRO4824 system. I'm using an ESS Smooth Stepper controller, MX4660 driver and a Huanyang VFD with a 2.2kw spindle motor and I’m using MACH3 software.

I’ve got everything working fairly well but I am not able to get the full 24000 RPM out of the spindle via MACH3. I can manually get 24000 using the VFD control panel but only about 21800 using MACH3. I’m using the 10 volt supply voltage from the VFD which is exactly 10 volts, going back to the MX4660 and the MX4660 outputs a control voltage of 0 – 8.5 back to the VFD, the MX4660 specs say the maximum output control voltage should be the 10 volt input minus 1.1 volts so the output voltage of 8.5 is a bit low but I’m not sure if that is the problem and don't see anyway to adjust that.

I can’t see anywhere in the VFD manual where the input analog voltage can be scaled to other than 0 – 5 or 0 – 10 so I don’t see a straight forward way of getting the full 24000 RPM out of the spindle using the analog control signal from the MX4660. I suppose I could use a different slightly higher voltage source for the 10 volt signal or even scale the 10 volts down to 6.1 volts with a resistor network and then configured the VFD for 0 – 5 volt operation rather than 0 – 10 volts.

I’m curious what others have done to get around this issue which I assume is common to all Leadshine MX3660 and MX4660 drivers.

[Leadshine]

Hi
This is a common issue for MX3660 AND MX4660 , the IC has 1.1V oltage drop ,so that the output is not 10VDC
I am sorry for that ,and we don't have solution for that .

John
Leashine

[islaww]

You should be able to set the Analog Input parameter(s) on the VFD to reach full rpm. Look for a parameter named something similar to "Analog input Offset" and or "Analog Input Gain" In your case with 8.5vdc the "offset" would be set to "85%" for full rpm at 8.5v

You may have to play with both to achieve desired results

[Joe2014]

You should be able to set the Analog Input parameter(s) on the VFD to reach full rpm. Look for a parameter named something similar to "Analog input Offset" and or "Analog Input Gain" In your case with 8.5vdc the "offset" would be set to "85%" for full rpm at 8.5v

You may have to play with both to achieve desired results

I agree there "should be" such parameters but there doesn't seem to be. The URL to the VFD manual is http://www.c-n-c.cz/download/file.php?id=47841 . The only parameter I can find is PD070 that lets you select 0 - 10 or 0 - 5 volt range for speed control. I tried the 0 - 5 setting and then used a 10k pot as a voltage divider to limit the output of the controller to a range of 0 - 5 volts and that did allow me to get the full 24,000 rpm out of the spindle but the linearity of the speed settings between MACH3 and the actual spindle speed was terrible.... unusable. I then went back to the 0 - 10 volt setting and am just living with the limited top speed. Linearity is still pretty bad but usable I guess.

I've tried calibrating MACH3 spindle speed control via several write-ups but none seem to work. Too bad MACH doesn't let you manually set up a table or something.

[ger21]

On a router, you really shouldn't need any rpm higher than 21,800. I'd just say leave it.

You're other options would be a standalone speed control on another port of the ESS, or a quality VFD that would let you adjust the rpm to the 8.5V.

[islaww]

Joe...
Gerry is correct, 21800 is probably good enough in most situations, I seldom have gone over 14K with wood (<400ipm)

You may want to check, and play with PD071, it sounds like it may help your situation.

Also... check to make sure that both Mach and the Leadshine box are producing consistent LINEAR voltages at step frequency commands. I have seen where one or the other will not respond in a consistent manner to a given PWM voltage command.

Too bad MACH doesn't let you manually set up a table or something Are you sure that that feature is not available? I am used to higher end control than Mach, where there are proportional scaling adjustments and individual step tuning for PWM and analog output controls. Also, am used to much better control on the VFD end with multiple adjustments. The combination of both of these allow user friendly accurate adjustments. Maybe these are features available on higher end products and you will have to live with what you have.

[Joe2014]

Yes, I've been able to do everything I want at 21,800 rpm, actually 18,000 works well for most things so I'll probably just live with it. The nonlinearity between MACH3 and the spindle RPM is an annoyance and I haven't really taken the time to make measurements at the MX4660 analog output or the ESS Smooth Stepper output to identify where the problem resides. I figure since there is no way to correct it, why spend the time making the measurements. MACH does have some spindle calibration logic but doesn't seem to work very well with an analog VFD interface. I think if I could provide rpm feedback to MACH, it may be able to control the speed properly.

Anyway, it's working well enough to do wood carving and some aluminum cutting. I tend to be somewhat picky regarding performance, always want to get things working as well as possible and these spindle speed issues just annoy me and I'm surprised many others haven't reported the problems. I suspect many just manually control the spindle rather than through MACH3.

[ger21]

If you've messed with the Mach3 calibration at all, try deleting the linearity.dat file (with Mach3 closed) and see if it helps.

[Joe2014]

Yes, I have deleted the linearity.dat file several times. I had found a fairly detailed write-up on how to calibrate the spindle and it said to delete the linearity file also.... and then DON'T run the MACH3 "Calibrate Spindle" function again.

I did get the spindle running a bit better this afternoon. I had set the Spindle Pulley values to 6,000 and 21,800, and apparently the 21,800 was causing the high end of the spindle speeds to be off, actually a couple thousand RPM too fast. I changed the 21,800 to 24,000 and now the speeds seem to be pretty close, within a few hundred RPM on most settings from 6,000 to 21,000. Of course any setting above 21,800 still gives me 21,800 since the controllers max voltage is slightly under 9 volts rather than the required 10. I'm pretty sure I tried 24,000 as the max pulley speed earlier but for some reason I switched to 21,800 . Oh well, the speed is working fairly well now so I think I will leave it alone.

Thanks all for the input and suggestions.