Instructions for fitting a 2.2kw (or other power spindle) and VFD


(Steve) #21

Hi, i read on one forum about programming the VFD that best to keep VFD above 100Hz or it overheats. This is maybe 3000 rpm? Do you have any thoughts on this having ran at 1200 rpm?
Cheers


(Luke) #22

Have you set your VFD to external controls?

Also is the spindle on button in CM? When it’s off is there any voltage going to PWM?


(Steve) #23

I set pd001 to 1 for external control. I think pd002 is external control of frequency, I left that as 0.
I have the other pd settings as you do. Using the spindle on/off in CM does nothing, I send the gcode for spindle off (M5) and for 24000rpm (after setting $30=24000) using m3s24000 and I measure the voltage across the VI and ACM and its being set to 0 or 5v but the VFD just doesn’t respond
Cheers


(Luke) #24

whats the voltage on the pwm wire? you don’t need to use the M5 command there is a button in CM that can be used for testing


(Steve) #25

Voltage on pwm wire ref to gnd I can change from 0-5v using gcode speed settings, I can measure this at the VFD end across the VI and ACM pins so I know I have continuity between the VFD and carbide 3d grbl controller. But no matter the voltage I give to the VFD it doesn’t turn on the spindle or change the speed. Maybe it’s that it isn’t getting the command to start turning forward, although I have checked continuity in the jumper between FOR and DCM and that’s fine. Hmmmmm …


(Luke) #26

Got you, so theres no issue with the board it’s more likely the VFD settings. What is your PD070? Also have you changed your $30 value to the max rpm?

can you confirm the following?

Connect the PWM pin to VI
Ground Pin to ACM
Short DCM to For with a shot wire


(Steve) #27

Finally i’ve sorted it! Thanks for your replies. I think the issue was with the VFD.
I used a potentiometer on 5v, ACM and VI to test with a switch between DCM and FOR. This made it easier to test the VFD standalone. It was setting pd002 = 1 that was the key. What is it set to on yours?
On all the blogs I read I think that people are just setting the values to make it work without understanding what they are setting. Here is my understanding, which may be wrong:

The VFD is a Variable Frequency Drive inverter. This takes your input voltage (100,120,220 etc.) and converts it to 3-phase (the inverter part). The spindles are induction motors (https://en.wikipedia.org/wiki/Induction_motor) and have no electrical connection to the rotor (no brushes so only the bearings are a wearing part). To make them rotate they need ‘rotational’ voltage (3-phase) where each phase is 1/3rd, 120deg out of sync (out of phase). This creates a rotating magnetic field.

Frequency: If the frequency is 1 Hz the peak and trough of each phase’s AC wave will be 1 second apart and I think the motor will turn 180 deg per cycle if it has 2 coils in the motor per phase.
the equation is: https://wikimedia.org/api/rest_v1/media/math/render/svg/5231fede7f546303caa0201cd3bd71403c501292
at 400HZ : 120 x frequency / 2 poles = 24,000 RPM, so it must be a 2 pole motor.

so to work out what frequency you need to generate a specific RPM:
frequency = (RPM*2)/120 so to get 6000 RPM you need 100HZ.

The speed of the spindle is controlled by varying the frequency. There are lots of warnings from people that setting the wrong frequency will fry the spindle. The VFD is often set at 50Hz from the factory and it will run too hot. If you reduce the speed of your spindle to run at 3000 RPM then you are essentially running at 50Hz. I’ve read that >100 Hz (6000 RPM) is safe.
The settings on the VFD just set the minimum at maximum frequency.

I set my VFD settings in this order:
pd013 = 8 resets the vfd to factory settings
pd005 = 400 max operating frequency (Hz)
pd004 = 400 base frequency (Hz)
pd003 = 400 main frequency (Hz)
pd011 = 0 frequency lower limit (Hz) should really be set to 100Hz but setting to zero allows 0v from the
PWM to turn off the spindle. maybe there is a better way with a digital output contacting a relay
between DCM and FOR. Not direct from arduino chip as VFD logic pulled HIGH 24v, GND
(DCM) to trigger
pd070 = 1 sets Analog in type 0-5v
pd072 = 400 higher analog frequency (Hz)
pd073 = 0 lower analog frequency (Hz)
pd143 = 2 number of poles in motor- changing this from 4 doesn’t seem to do anything??
pd144 = 3000 rated motor revolution. Ok so the motor is 24000rpm so i thought setting this to 2400 (only 4
digits available) would be right but then the rpm is way off at 400Hz
pd001 = 1 sets the VFD to use the contact closure (24v) from DCM to FOR to start forward rotation
pd002 =1 sets the VFD to use the VI and ACM to control the frequency (and thus the speed)

PWM output from GRBL board outputs 0-5 VDC, referenced to its GND pin.
VFD is set to receive a 0-5 VDC analog input to control the speed.
send gcode $30=24000 to shapeoko to set the max spindle speed at 24000 RPM. This means that if you ask shapeoko to go to 24,000 RPM (gcode m3s24000), it will output 5V to the VFD.
The VFD is set to a high analog in frequency (pd072 = 400) of 400Hz, so the 5V will give 400Hz which = 24000 RPM.
Setting spindle off (gcode m5) will output 0v, 0Hz and 0 RPM.
Setting the spindle at <6000 RPM will set VFD to 100Hz and is supposedly bad for it.

I think I will look at making a way for the grbl board to switch the FOR control using a relay, or have this as my emergency stop.

Another useful thing in the VFD settings is the Acceleration and Deceleration control.
So, I don’t know what parameters are safe… but setting pd015 = 2 (default 10 seconds) will make it stop in 2 seconds. This is much better for cutting off the spindle safely.


(Luke) #28

Great deduction.

Worth noting that start speed and stop speed can be allot faster than that, I’ve heard of people reaching 24000rpm in a second. Same with Decel time - I haven’t changed these yet but it’s on my list to do.

I don’t think you want to use a relay for emergency stop - there is already pins of the S3 board to acomodate that and it will stop the machine and the spindle.

Have you grounded your spindle? If not make sure you do - it will cause issues if you don’t. It’s likely the pin on top is not connected to anything inside the spindle - easy fix is available.

Worth noting all the PD settings and meanings are in the manual Spindle Instructions.pdf (726.2 KB)


(bjbm) #29

For the life of me I just can’t get it to run in software. Did everything you did Luke, as well as what steve suggested above. No go. It runs fine manually. I even tested the voltage across the PWM and it seems fine,s o the carbide board is sending the right signal. Stupid VFD just isn’t listening.


(bjbm) #30

Update: Got it to work!!! ONE missing step (at least for me) is you had to set Jumper 1 (J1) over VI (1-2) to allow for external potentiometer/external PSU.

I’m surprise you guys got yours to run without this? Maybe all these models are a little different.


(Gary) #31

I see this is the information I need to set mine up for speed control. Thanks


(Gary) #32

OK Luke,

I’m finally able to get some work done and I set up my spindle for computer control per your instructions in this thread. My issue is when I hit start after setting up for a cut it goes to the bit change position and spins up the spindle. And while I’m good I’m not good enough to change out a bit at 8333 RPM’s. so I have to hit the stop on the VFD. Once I do that the only way I’ve found to get it running again is to unplug the VFD power and let it cycle down completely then plug it back in.

Did I possibly do something wrong?


(Luke) #33

I think something is wrong but I’m not sure what.

What is your bit change position? Usually I go to bit change position, change the bit, find datum (job start) then start the program?

Sounds like you are trying to change the bit after you star a job?


(Gary) #34

I was just watching your video it said you right click on start and the spindle stops.

My bit change on my XXL is the front left corner where I zeroed the spindle. when I hit start it will go up some and the red box display comes on and tells me to install the correct bit. but at the same time it spins the spindle up to speed.


(Gary) #35

Said you right click on the forward button to stop spindle, the red box is white with the red “continue” on it.


(Luke) #36

that sounds like you are running things from the middle of a program. Either that or you have a macro with M commands in which starts the spindle.

Can you do a quick video?


(Gary) #37

No, I’m starting the computer and turning power on to the controller. Once the PC starts up I open CM and connect to the machine. I DL the .nc file hit jog the machine asks if it’s OK to home, I click yes. It goes through the homing cycle. Then I jog it to the zero point and zero all axis’s then I tell it to start where it goes to the bit change position and spins up the spindle while the box with the red button comes on telling me to install the proper bit.


(Gary) #38

I can do a video tomorrow if necessary. I need to get some sleep soon. I have to go back to work a little later.


(Luke) #39

Ah your using carbide motion? Thought you were using UGCS?