Hair already gone. pulling teeth out next...spindle tuning issues...

[natefoerg]

Well, after several days of screwing around with my setup, I am at a complete loss.

here is the setup-
Mach3 3.042.040
SS Vo15ogx2
CNC4PC index pulse board
CNC4PC C6 speed control board.
Automation direct GS2 110v in 220V 3ph out VFD.
1 HP marathon black max inverter duty motor.
approximately 1:6 reduction between the spindle pulley and the drive motor pulley.
1.5 inch 1 slot disk on the back of the lathes original tachometer assembly.

I have things up and running. motor is running through the VFD controlled by 0-10Vdc (although i cannot seem to get more than 5V actually) from the C6 board.
the index pulse board is recieving and and transmitting pulses just fine- AFAIK.
I can see my actual spindle speed in mach, but it has no relation to the M3 S*********x command thats imput.
I have tried everything I can find. I have adjusted Spindle motor tuning, C6 boards output voltage, index debounce, SS setup dialog adjusted "step and direction" pulse width, pulley ratio etc..

I have fiddled with the settings so much, that i cant get them back to even being useable (if even innacurate) i could use a baseline for all of these different settings. unfortunately, the automated spindle setup does not get things working even close to what they should be, and to compound that, I cant find out anything about the "PID" settings, what they should be, what they even are etc. the mach3 lathe manual does not even appear to refrence PID. and I have searched the web with no luck.

I have read the mach3 manual, and I cannot seem to find any reference to what the "steps per" should be under motor tuning/spindle. intuitively, I would think that it should be 1/rotation with an AC motor. unfortunately, this setting seems to make the spindle not move at all. 60 seems to work reasonably well, but this bares no relationship to anything i can think of, and so im guessing is incorrect.

In general, I find the SS documentation poor, the Mach3 doccumentation slightly better, but both have really dropped the ball when it comes to helping me setup a VFD controlled spindle.

Any help would be GREATLY appriciated! I certainly need it.... 

[M250cnc]

Ok i will assume you have 12v to the input of the C6 board

Set the trimmer pot to the centre position

Set a least one pulley up that matches your maximum & minimum speed

UK ac is 50Hz i use the VFD at a max of 100HZ

My favourite speed on the lathe is 550 rpm at 50Hz now will go to 1100 rpm at 100Hz it is pulley seven of nine the minmum i use this pulley at is 275 rpm at 25HZ

Now you set your speed to maximum set up the spindle in motor tuning but the steps per and velocity are just made up numbers but while you are doing this i suggest you have the VFD disconnected

What you are aiming for is at your max speed you have 10v and at half speed you have 5v and so on

The thing that got my hair pulled out was i had to set the pulse with on the SS config page to 11.5 (us) you do not need PID numbers as i believe these are for servo systems.

Just keep adjusting the pulse width until you get close to 10v when almost there then you can use the trimmer

Then to test you set at half speed then measure voltage to make sure it is 5v then the  voltage slope should be linear

When you have got the voltage right then  connect the VFD

On my favourite pulley i am accurate to 2 rpm as i trimmed the pot to give a matching speed on a digital tacho.

I can't emphasize enough you must set at least one accurate pulley then you just set all your other pulleys accordingly.

[chrisjh]

I too lost some hair and considered biting something really hard!!

I finally cracked it!!

Have a look at my experiences at www.cjh.com.au/PWM Spindle Control using Mach3.pdf

Hope it helps.

Regards

Chrisjh

[Promech]

Thanks for the document, its very useful.

Any comments as to how to configure the VFD parameters so that you can run the motor at very low speeds without driving the current up?  In my case I use a 3600RPM spindle motor. When I go below 300 RPM I start to get overcurrent faults. I would like to go as low as 150 RPM.

Promech

[chrisjh]

I don't recommend running motors at low speeds because, induction motors do not have much torque at low speeds and, as you have found, the current increases.  You will also find the motor will run hotter for two reasons:

1.  Increased current, and

2.  The fan in the motor will not pump as much air through the motor making the motor hotter again, compounding the problem.

If you need to run something at lower speeds you should use a gearbox or pulley system to reduce the speed and keep the motor revs up.

I have deliverately set the lowest speed of my lathe motor to 20Hz (which equates to approximately 576rpm) to keep the fan pumping air at a reasonable rate.

Regards

Chrisjh

[jaja]

Have a look at my experiences at www.cjh.com.au/PWM Spindle Control using Mach3.pdf

Hope it helps.

Regards

Chrisjh

Chris
You cant realise how much you helped me with your PDF document.
I followed up your guide of how to make your spindle work,, and now, at last it works!! Super! Thanks.

One question: what number is on your "index debounce" in config > general config> index debounce, since you have a device for a DC output?

gr jaja

[chrisjh]

Hi Jaja,

I have attached my General Config Settings.  This works for me.

I set the debounce to 30.

Regards

Chrisjh

[polaraligned]

Chris,
Thank you for your generosity sharing your experience.
Your document should help me greatly with my lathe.