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General Mach Discussion / Parametric Variables Table??

« on: April 25, 2014, 12:27:04 PM »

I'm wondering if there is a table somewhere, which I cannot seem to find, of the variables Mach 3 uses.  I often find myself machining cast parts that will vary in thickness.  As such it's difficult to machine them consistently.  I've come up with a simple electronic circuit that uses the tool and G31 to sense the top of the part and then say drill a screwhole with countersink to a depth below that measured height.  The fixture holding the part is insulated from the vise, the circuit uses the probe input.  It works great.  The code is;

G00 (to just above the part)
G31 (to touch the part, completing the circuit, about 20 microamps flows through the spindle bearing at about 6 or so volts)
#101=#2002 (transfers system variable for the Z axis height on touch to a user variable)
G01 Z[#101-0.405] (0.405 is the depth to drill a perfect screwhole)

The problem is I cannot use coolant with my current system as it conducts electricity and will give a false reading or error.  I have a new situation that I must use coolant.  I want to cut a slot using a sidemill into a part that also varies in thickness (Z height varies). I can manually touch off on the top and bottom of it.  Slow but should give consistent results.  I would like the Gcode to be able to use the current Z position in it's calculations, which of course would make it a lot easier than doing the calculations by hand and then entering them into the Gcode each time I machine a part.

The problem is that #2002 seems to only be set by a G31 function, which won't work in this situation because of the coolant.  Is there a system variable that can be accessed that has the current Z value?

I'd prefer a list of all variables if there is one.

Thanks,  If anyone is interested I can do a write up on my circuit.  It's quite simple.