just flicking spindle on and off with a relay

[Jonathan]

Have you checked on the diagnostics page in mach3 if the output for the spindle is actually changing state? The diagram of the parallel port showing the pins should light up.

Try something like:
M3 S1000
S sets the speed, might have to set the speed for it to work. I can't remember exactly as it's been a while since I used mach3 and I can't look into it now...

[JAZZCNC]

It's a simple thing so If you have output 1 to 6 setup with pin 17 then it should work and from what you have posted everything looks correct and it should work.!! . . . So this tells me you either have selected wrong pin on board or pin is knackerd.!! . . . Try different output pin.

[EddyCurrent]

I don't know what error checks Mach3 does but I can't imagine it would let you select the same output for Clockwise and CCW, have you tried setting CCW to another spare output ? then M3 should operate output 1

[birchy]

Are you using a digital test meter? I'm just wondering if it's a pulsed input that only an analogue meter would show?

[kingcreaky]

right... Im now able to turn on 5v and turn off 5v to a pin, by running the m3 command etc.. however it seems there is not sufficient power to pull a relay.... therefore... how do I get from the 5v signal... to flicking the spindle vfd on and off?

i assume an opto coupler?

[irving2008]

As Jonathan said, you need to find the 'Run' input on your VFD. What model is it?
You shouldn't really switch supply volts to a VFD.

right... Im now able to turn on 5v and turn off 5v to a pin, by running the m3 command etc.. however it seems there is not sufficient power to pull a relay.... therefore... how do I get from the 5v signal... to flicking the spindle vfd on and off?

i assume an opto coupler?

[birchy]

As mentioned above, most VFD's only require a N.O. contact between 2 pins to trigger the start/run signal, so you'll have to use a switching circuit such as a miniature relay or a semiconductor (transistor, etc).