Z axis crashing into touch probe - why?

General Chat
1

After homing the machine, I jog X, Y, and Z to near the corner of my 19mm thick MDF part. I then position the TP on the corner of the part and connect the magnet to the 12.7mm end mill. At this point, I like to pick up the TP and touch it to the bit to confirm the indicator shows Active - it does. I then select the upper left corner icon in the probe routine.

Normally, the Z moves slowly closer to the TP until it makes contact then backs off. But now it moves much too fast and crashes into the TP and I am at a loss to understand why. I cycled power on everything and tried again with the same results - I hit the EStop button before it hit the TP.

The machine ran fine just before this, but I did make one change: I switched the machine to metric units from inches. I suspect this is somehow at the root of the problem, but all the machine settings appear to be correct.

Here’s a screen shot of the current settings (I have never changed these)

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I’m thinking my next step should be to reload the machine profile(?)

2

Although it’s not at all clear to me why this resolved the issue, reloading the machine profile did the trick.

I used the Mach 4 GUI tool to restore from an earlier backup file, in case anyone is curious.

3

I’m curious if the old profile you reloaded was in inches or metric and if in inches did you change it to metric, then it worked this time. Thanks!

4

I had this problem in the previous version of the software. Took a bit of work to figure out, but the root cause was that the routine I was running just before using the touch probe left in it relative mode. (G91 mode) In my case going into the MDI screen and executing a G90 to bring the software back to absolute mode was enough the cure the problem. Not sure if this is the exact problem you are having but it may add a little more data to the problem solving you are doing.

5

Both the current and old (reloaded) profiles were G20 (metric).

hth