I would like to install a laser detector with a laser pointer to slow down the Z axis when measuring tool length on my tool setter.

This setup would serve as a switch with mach 3.

I would add to my tool setter macro a function, G0 until laser is cut by the tip of the tool, then go G1 F3.

This would be great since tool are sometime 5 inches long and sometime 3 inches long.

Maybe a small infrared receiver could do the job.

Thanks for any advice, Jeff

I dont see that this would be too difficult. I have lasers on my lathe/mill for positioning. The lasers shine at detectors, and are accurate to 1 thou of an inch. I dont see you are even asking for that accuracy.  A laser shining across your tool height setter at a detector would be picked up when the tool broke the beam.

I wont give details of my lasr and detector, because you probably can't get them - but the laser was £10 ($20) from Maplin, and the detectors are a few pence. They are very simple - three wire +5v. 0v and output. The output goes low when the laser is detected. Scmitt trigger output means it controls the input pin directly.

I made the laser and detector a little more accurate by shining them through 1mm holes about 12 mm long.

Any pics of your setup, Jim? Sounds exellent - 

I don't ask for accuracy, I ask for some kind of detector.