Still working on my homebuilt system..it has been one problem after another...bad motors, bad power supply, racking of the gantry, oval holes when trying to drill and the list goes on.

Anyhow, I think I finally got everything tightened up and clamped a 3/4" x 6" x 14" piece of mdf on the table and launched Mach3. Thought I would try something simple for a test cut and ran the Text wizard and just did a simple 2" high bold letters gcode that said TEST CUT". Nothing fancy for sure. put a 1/4" 60deg V-carve bit in the router, set my 0 ref point for X, Y, and Z. turned on the router and dialed in a 16000 rpm and started running g-code on mach 3.

Ok..first the router moved to start the T, lowered Z down to -0.125 where I had defined it..cut the T, raised up to .5..moved to E, lowered to -0.125 and did that cut. after raising up to .5 and moving to the S position, instead of Z lowering to -0.125 as the code showed, it instead plunged straight down through the mdf and into the spoilboard.

I did emergency stop..raised Z up...and re-zeroed. checked everything and with it looking good, started up again. exact same thing happend..on the 3rd letter, Z axis plunged full hilt.

so, any ideas what would be causing this anomoly?

Mike