You are correct, Simpson36, that is what I'm trying to achieve, and yes, the controller doesn't seem to want to know. The developers of the ncPod don't know if it handles step/dir for spindles, but assume it does. they don't know Mach3 well, apparently. I'm surprised they haven't tested this feature, but there.
I take heed of what you say about speed problems in combining/ interpolating rotary and linear axes together, in fact I'd considered using the z axis to drive the pump for that reason. Only trouble is, that might make generating the g code difficult,as I already have a physical z axis, so I'm hoping there's a way to configure the a axis as another linear axis.
Do you know if this is the case?
The problem remains in either case of 'fixing' the ratio between x axis movement and pump axis movement during 'painting' (Assuming the axes can work well enough simultaneously.) This is where I may need to write an app to edit my gcode that works like
'read x axis value
divide by the number needed to get correct ratio
add this new value into the code and precede it with the designated axis letter'
This might be easier than trying to generate the pump axis code in, say, Cam Bam or whatever g code generator end up I using. This simple approach won't allow for non simultaneous starting of both axes, of course, but it's a start. Once I get the principles involved in getting to this stage, I should be able to have a go at more sophisticated stuff
I have no idea how to do this yet; it feels like it should be simple, but I bet it won't be!
Any suggestions?
Thanks,
Richard B