Hi, I have problem with my lathe. I want to pull a relay when I command M3 or M4.
I hav eunchecked the "Disable Spindle Relay" and choosen Output 1 on both m3 and m4.
Cant make it work.
/Jim

Hello,
'What pin do you have the output set to? You can check this under outputs (also be sure that the port is set)

Thanks
Brian

Also check that the printer port output has the power to drive the relay.

I was connecting to my Omron inverter, but had to drive a relay with a simple transistor amp to get it going.

What do you have for a breakout board?

Brian - I don't know whether that was aimed at me - I don't have one. I got an old printer lead and identified all the wires in it with the pin numbers and soldered them, in order, on a small piece of copper clad stripboard.

The wires to the stepper motor drives go directly to those boards. The other functions I make the circuit up as required. At the moment it is just the two spindle relays for M3 and M4 commands. I have to do the coolant relays next.

I don't know how to stick a picture on this forum, or I could put one up.

You will need to do some work to get that output to drive a relay

Hi,

The easiest way to go is, Solid-State Relays , Most of then are 3-30 volt input (Opto-Isolated) and are available in many flavors.

Thanks, Chip

Getting the parrallel port to drive relays is fairly easy. 
The books I have are fairly old hat now, but more modern transistors can be used. I am looking at the design now - which is a BC 549 transistor, fastened to ground, with a relay up to a 12 volt line.  It is driven by the 5 volt signal ( or in actual fact the 0v signal ) from the parrallel port via a 2K2 resistor There is a diode across the relay pins (to protect against voltage spikes etc and a 3K9 resistor base to ground. Only four components.
I had suitable values in my bits box to knock up two similar circuits for the spindle motor pins. I have a resistor to cut the 24 volt power supply for my stepper circuits to 12 volt of these relays - and since only one of these is on at once, one resistor is enough for that.The relay outputs go to my Omron inverter.
I can repeat this for the coolant relays - with the advantage that the seperate circuits are completely isolated from one another - via the relays.