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I've Just Got My New VFD & New Motor Running But
« on: April 24, 2008, 02:08:11 PM »
When i run code all G0 moves slow the spindle 50%

I also set the spindle running and then jogged the length of the table, again the spindle immediately dropped 50% while jogging, then sped up when stopped.

Is the how it's meant to be ?

Are there any settings that can be adjusted.

Version 2.63, CNC4PC C11g BOB

Thanks
Phil_H
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline jimpinder

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Re: I've Just Got My New VFD & New Motor Running But
« Reply #1 on: April 24, 2008, 02:38:51 PM »
I assume VFD is variable frequency drive controling the spindle motor.

I assume you have it control by the PWM output from Mach 3.

Is the answer is Yes - then NO. The spindle speed is not affected by jogging up and down.

I would check your Ports and Pins/Spindle configuration. The PWM signal is given out on the "step" pin. The direction pin should remain at 0. Set the Step Port at 1.

The only reason I can think of that the spindle speed drops by half is if your return wire from your VFD is perhaps another "step" wire, and the two signals are interfering with each other.

Check your configuration

Not me driving the engine - I'm better looking.
Re: I've Just Got My New VFD & New Motor Running But
« Reply #2 on: April 24, 2008, 03:10:33 PM »
Thanks Jim

Yes the VFD is a Variable frequency drive.

The VFD is adjusted by an analogue voltage, the Mach spindle motor setup is Step/Direction Motor

There are NO Wires connected to the step and direction pins for the motor.

But at least i know it's NOT meant to be like that.

I will be playing with it again shortly.

Phil_H
« Last Edit: April 24, 2008, 03:12:08 PM by Phil_H »
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline jimpinder

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Re: I've Just Got My New VFD & New Motor Running But
« Reply #3 on: April 24, 2008, 03:44:17 PM »
Yes - You need to use the PWM output from Mach3. If you look at Ports and Pins/Motor Outputs then if you look at the Spindle line, the PWM output is on the "step" pin. You can allocate this to what ever output pin you like.

The PWM needs to be converted into a voltage - and the best unit to do this is a Digispeed - (Australian). All you need is the cheap DC 01 board.

This takes the PWM siganl from Mach 3 on one side of the board. On the other side, three wires come from your VFD - a positive voltage, a ground 0volts and the input wire. Digispeed automatically converts the PWM signal to a voltage between 0v and the positive voltage, corresponding to the PWM signal.

The two halves of the Digispeed are electrically isolated from each other.

It is relatively simple to wire up.
Not me driving the engine - I'm better looking.
Re: I've Just Got My New VFD & New Motor Running But
« Reply #4 on: April 24, 2008, 03:54:37 PM »
Thanks Jim

That is all built into the BOB from CNC4PC

I used the supplied XML file from CNC4PC to get an idea of what pin settings to use.

Phil_H
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline jimpinder

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Re: I've Just Got My New VFD & New Motor Running But
« Reply #5 on: April 24, 2008, 04:21:23 PM »
In that case, check with a voltmeter the voltage your BOB is giving out to the VFD, both when jogging and when not.

In should not change.

Are the pin numbers on the BOB all pre - allocated - e.g. axis 1, axis 2 etc etc - and you have to set Ports and Pins to suit ??.

I can only think that you have the same pin allocated to the Spindle "step" and to an axis "step"  Without jogging the PWM (Pulse Wave Modulated) is OK.  If you can imagine a square wave of a fixed time interval, -  then on 0, all the wave is at 0, -  at 50%, half the wave is at 5v and half at 0v,  - at 100% the wave is at 5v all the time.

Step signals to axis motors are pulses, square wave with a fixed time span (depending on your time settings on Motor Tuning) - the frequency of the pulses depends on the speed of the jog.

If the two are combined, then the axis stepper pulse will turn off the PWM pulse for some of it's time,(the 0v pull down pulse being stronger than the +5v)  and so the converter on the BOB will translate this as a lower voltage.

A very detailed idea of what I think is wrong - but short of something actually being faulty, I can't see what else it can be.
Not me driving the engine - I'm better looking.
Re: I've Just Got My New VFD & New Motor Running But
« Reply #6 on: April 25, 2008, 08:13:18 AM »
Thanks Jim.

I have fixed the problem.

I found that my ports and pins page was set to Sherline mode, this was in response to an earlier problem.

One day i will spend more time using the machine than setting it up. ;D ;D ;D

I will leave the answer here so that it may help someone in the future.

Phil_H
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable