I have access to a 770 mill. It has a passive probe and an ETS. I just updated to the newest version of path pilot because the ETS was not supported on the old version we had.
What I noticed is the ETS agreed with manual measurements I had taken of tools previously.
The probe measured accurately in the z axis when I set the origin. Then move it up a given amount that was correct.
When I put a tool in and do G0Z0, the tool would go below the origin by a set amount (0.0878") with each tool. This was annoying, but I found that if I subtracted that set amount from the probe length in the offsets then it was “correct”.
I did try to rereference the probe and also measure it manually, as well as the ETS. They all were unchanged. If anyone has an idea what might have caused this discrepancy that did not exist in the past I would appreciate some information.
Unfortunately even with the probe offset adjusted it seems like the Z0 was wandering for some reason.
I ran the facing program created in fusion 360 part way and realized I had not gotten air out of the mister line. I stopped the program. Reset all the zeros and then reran the program thinking it would just cut air at first, but the Z0 was at a slightly different height. I stopped it again since the height of the pass was clearly wrong. Then I reset all the zeros again and it would do something else. Sometimes z0 seemed to go up and sometimes down. But it only seemed to cut at the correct depth one time.
At first it seemed it moved by the offset I put in for the probe. Almost as though it fixed itself, then it went the other way. Unfortunately the probe ETS discrepencay of 0.878 and the cut depth of 0.0866 are close so it muddles up what might be going on. If you reset zeros with a program loaded does path pilot get confused? (Thinking the work offset is messed up somehow). In any case if anyone has an idea of what might be causing these issues I would apprecaite it.
Someone did “fix” the mill when I was away. They did not like it being set up in metric and changed to standard (imperial) units and who knows what else. I looked through settings though and aside from the deleted G30 reference could not find anything problematic. This was before the software update. I still see nothing weird.
What were the steps you took to reference the probe?
It sounds like your probe length is wrong despite rechecking it. Using it to set Z0 and verifying that it’s correct by moving it up a given value only tells you that the machine is moving correctly in Z. No different than touching off a tool on a workpiece, jogging up an inch, and seeing that there is now an inch between the tool and the piece. That doesn’t set the length, it sets the Z0 location based on the length that is already set for that tool.
When stopping a program partway through, there’s no reason to reset the zeros. If you are adjusting your Z0 every time you stop the program, you are likely setting it incorrectly.
All of this is conjecture as I’m not entirely sure I understand the steps you’ve taken so far but based on what you’re written I think what you’re seeing is a combination of incorrect probe length offset as well as operational errors while running your facing program.
Strike that last one. Check your wiring to your z servo. Sometimes a loose connection can reduce the torque and it can loose a step at the top or bottom. Especially the ground pin on the steppers. If the ground shorts out the motor will try to ground to the frame and its a lot higher resistance so the motor works but looses a lot of power.
I will check the wiring. I think it is a bunch of things at once probably and that is why it is confusing.
I referenced the probe as it says in path pilot.
3 inch block, put the head on it with nothing in it and the collet retracted to reference it. Then put in probe and measured the length.
I will triple check the ETS as I am not sure what the person who initially put it in did. I also found that the facing mill was loose from its holder and could move up and down a bit. That could explain much of the weird movement as well, but something else is going on also I believe either the wiring suggestion or the ETS probably.
Sometimes the ETs has an overtravel that is supposed to be wired into the E-stop. If that’s wired to the tool touch pin it might be triggering but at a lower distance than it should be.
Well it turned out that the person that “fixed” the mill and installed the face mill used an M5 bolt to attach it to the TTS-1/2 in. Shell Mill Arbor instead of a 1/4-28 thread bolt. This meant that the face mill was not tight. It chattered and the threads on the bolt were stripped affectively allowing the face mill to move up and down. this randomness was the issue. After fixing that it seems as though things are ok. The ETS length had been incorrect as well which explained the offset issue with the probe. I just referenced it instead of setting it up since the length was already entered and it was “set up” even though it wasn’t really. That was my bad.