I'm not sure if this is a good idea or not.

My first idea is to use a micro / optical switch on the gantry to trigger a coolant pump when Z reaches a certain level. I may still do this if this next idea won't work.

The question is, since "zero" can vary from one project to the next, it would be nice to have the coolant pump trigger be software based instead of mechanical. Otherwise, each setup would require a manual adjustment to a mechanical or optical switch.

Would there be a brain or vb script that could trigger an LPT pin high when Z reaches 1mm or below?

Thanks,

Z 

I would imagine you could use a macropump to do it, just have the macropump look at the Z Dro and if less than the value you want have it switch on the output and if greater switch it off.
Hood

Just thought I'd post back again to say I was able to get this all working. It's cooler than I expected

I added a button to enable / disable the auto coolant flow, plus a check to make sure the machine was out of E-stop mode, and that the spindle was on before pumping.

Thanks,

Z