Tool lengths changed

[de5]

Today I had a lot of problems related to cutting too deep. I checked the tool by touching it to the fixture and it was .1 too long. I thought it slipped out of the collet so I did a 'measure tool' and tried the file again. This time other tools cut too deep. I ended up checking every tool by touching them to the fixture and all are .1 too long.

The fixture is still bolted firmly to the machine frame. What could cause this?

[Gary Campbell]

Charlie...
Do you use a G92 Z offset to the fixture? Any chance the error could be there?

[de5]

Gary,
I have not done a G92Z to try to fix the problem, if that's what you mean. I did re-initialize and that didn't fix it. Then I turned off the pc and restarted it, and that didn't fix it either. I am using a home position for that fixture, and the post processor I use automatically puts that home position at the beginning of the file.

EDIT: Oh, now I think I know what you mean. If I am understanding you, the answer is yes. When I checked each tool, I typed G0H4 (the home position of the fixture) then brought the tool down until it touched the fixture. The wincnc screen read Z.1 The file I was running begins with G0H4.

I think I'm gonna go out and measure all tools and try again.

[rcrawford]

Charlie, not sure if I'm understanding your last post correctly. But when you measure a tool, the TLMS actually compresses about 0.1" before it registers. So if you are bringing the tool down until it just touches the fixture, then that could be why you are getting the Z.1 reading.

If you calibrate your TLMS and remeasure the tools, do they stay accurate to your spoil board?

[de5]

Russell, I don't see what the movement of the switch has to do with anything. The switch is calibrated to the spoilboard. I have re-measured all the tools now and everything is working fine. I would just like to know what changed or why it changed. I am at a total loss.
I will keep an eye on it over the next couple of days.

[rcrawford]

I could be wrong, but I always thought the switch doesn't 'activate' until it is depressed a certain amount. So it is calibrated at the depressed state where it opens the circuit, rather than at the surface of the uncompressed switch.

[de5]

I could be wrong, but I always thought the switch doesn't 'activate' until it is depressed a certain amount. So it is calibrated at the depressed state where it opens the circuit, rather than at the surface of the uncompressed switch.

Yes, I agree with you. This is my understanding of how the switch works too. So whatever distance the switch moves before it activates doesn't matter. Why would that distance be relevant to my problem? I must not have explained the issue very well.

Update: I re-measured all tools and cut the parts on my fixture as usual with no problems. Tomorrow I will double check the tool lengths before cutting anything.

[james mcgrew]

Check to see if the pad on the tool sensor is loose, it will rise when loose, Yes i had to learn this.

[de5]

Thanks James, that's good to know. I will check it when I get to the shop. The thing is, all the tools were fine...for years....then yesterday they were not, and I didn't use the tool measure switch. Something changed and I have no idea what I could have done to cause it.

[james mcgrew]

Pad screws on, Mine came loose over years and i had a heck of a problem, a little anti sieze solved it

[Gary Campbell]

Charlie...
I have a few questions about procedure. Could you give me a call when you have a few?

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