Probe resets Z in middle of session

[rob_jones]

Has anyone had this problem before: When I set the probe up to run, it will go great for a while and then it appears like the Z zero jumps up about .350" and keeps going. I came out 30 minutes into this probe and it still looked fine, when I came out at the end I saw it probing air about 3/8" above the lower Z limit. This is what the file looked like after:
7117
I can see where it happened, I can't see WHY it happened. There was nothing special about that part of the shell, it was the 1804th point collected, and this has happened before with the same jump in the Z axis.

[Brady Watson]

Robert,
Chances are that the probe trigger switch inside got stuck in the actuated position. Take a few minutes to wiggle the probe stylus and make sure that the input 1 light goes off and then back on reliably. Push, pull and flick it to make sure it is reliable in every situation. If it hangs with input 1 light out, then you'll need to adjust the sensitivity of the probe. If using an early probe, adjust the brass screws - on a later one, adjust the white sensitivity screw.

-B

[bill.young]

Robert,

I'm guessing that the "jump" that you're talking about is the ramped section toward the left of the picture. If all the rest of the points are offset by the same distance after it makes the jump, like everything is just moved up, then it sounds like the Z-axis has lost position for some reason.

Does the Z-axis go back to the original location after it's made one of these jumps...does it go back to the same Z-axis zero position that it started at? Have you tried slowing down the Z axis..does that make a difference?

On yeah, is your ShopBot software up to date?

Bill

[rob_jones]

The probe appears to be working fine. I watched this as it happened trying to figure out anything, on the red box on the screen when the probe is moving downward to find a point, I see the lower limit number flash just long enough to identify it but the tip is no-where near that dimension. Actually, another thing I thought was weird was, if I use jog to bring an axis to a specific spot, I notice the number on the red box screen will show it's there before the motors stop the axis from moving. Is this normal?