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Help Please with PWM Spindle Motor Speed
« on: August 03, 2014, 05:00:57 PM »
Been on best part of a day trying to setup my new Spindle Motor. The problem is in trying to calibrate the actual Spindle RPM to the Mach3 DRO RPM.  I am using 35KHz base engine and setting the PWM Base Frequency at 60 does nothing for it as it still runs about 20 times faster than the DRO.  I don't seem to be able to find the right answers in the Mach3 Manual. To give an example, using the MDI at S1000 the motor is doing 5,200 RPM and I don't seem to be able to bring the two together.

Once again thank you in advance for your response, only kindly note that I am still an (old) newbie to CNC so please do not baffle me with mathmatical calculations I just want to use the Mill not re-invent it :)
God created Ale to make us all happy ..... 8)

Offline DMBGO

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« Reply #1 on: August 05, 2014, 12:49:05 AM »
Mach gets its speed reading on the DRO from the spindle index sensor. Sounds like you might have an issue there.

Regards David
Cheers

David
Help Please with PWM Spindle Motor Speed
« Reply #2 on: August 22, 2014, 05:49:40 PM »
How are you converting the PWM output to control your motor?  I assume you don't have a spindle speed sensor so the system is open loop. There needs to be a calibration adjustment in hardware between the PWM smoothing and the speed controller.  PWM base frequency is not directly related to spindle speed, it's just the frequency of the pulses whose pulse width is controlled to indicate the desired speed.  Normally you smooth those pulses to generate a voltage, which is scaled for calibration purposes, then applied to the speed controller.

Offline ger21

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Re: Help Please with PWM Spindle Motor Speed
« Reply #3 on: August 22, 2014, 07:46:21 PM »
Have you set up your pulley speeds? Those are what control the rpm range.
Gerry

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Re: Help Please with PWM Spindle Motor Speed
« Reply #4 on: August 23, 2014, 10:51:35 AM »
I'm having some major life issues at the moment to where this is going to have wait a bit, My Wife passed away last month after a very short illness, I'm now wishing I had spent more time with her rather than fiddling on with all of my dopey assed projects and hobbies.
God created Ale to make us all happy ..... 8)

Offline Vogavt

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Re: Help Please with PWM Spindle Motor Speed
« Reply #5 on: August 26, 2014, 09:26:52 AM »
My condolences to you.

This should be a "Lessons Learned" for all of us.
Re: Help Please with PWM Spindle Motor Speed
« Reply #6 on: August 27, 2014, 07:09:14 AM »
Thank You I feel it will be a good while before I can get my head back into anything. The guilt is almost as unbearable as the grief and lonelyness.
God created Ale to make us all happy ..... 8)
Re: Help Please with PWM Spindle Motor Speed
« Reply #7 on: November 10, 2014, 02:01:07 PM »
I am back again from a being in a very dark place for a while. I feel I need to try and keep myself busy to take my mind away from reality.

Where I left off in July was in trying to configure my spindle Motor which is still giving me a major headache.  The problem I’m having is managing to get my Spindle DRO to match the actual spindle RPM and it looks like I need to set my pulley ratio’s at something like 5:1 But for whatever reason I cannot fathom out how to set it.

My Pulley setting dialog box is different to that in the Mach3 Manual to where I have an independent input panel rather than it being part of Ports and Pins dialog box. Have I an old distribution which needs updating?  I have Version R3.043.066??

As I said above, I think I need a ratio circa 5:1, (Driver Pulley 5T Driven Pulley 1T) How do I go about entering that into my Settings.

As always, any help is gratefully received. 
God created Ale to make us all happy ..... 8)
Re: Help Please with PWM Spindle Motor Speed
« Reply #8 on: November 10, 2014, 04:46:36 PM »
Hi
Are you sure your motor pulley is 5 times bigger than your spindle pulley?

Mick
Re: Help Please with PWM Spindle Motor Speed
« Reply #9 on: November 10, 2014, 05:42:40 PM »
Thank you for your reply Mick. I might have that wrong. I need the (VIRTUAL) Driver Pulley to turn 5 times as fast as the Driven Pulley.

I have poked on again this evening but nothing seems to be making any sort of sense.  At one point I seemed to make some sort of progress to where the Spindle Motor would run at almost twice the DRO RPM but then it stopped showing the speed on the display...

This is really bugging me now to the point where taking up knitting and ballet is becoming a distinct probability.
God created Ale to make us all happy ..... 8)