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Topics - lsteele

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General Mach Discussion / Mach3 Turn tool offsets just don't work
« on: June 11, 2017, 11:28:08 AM »

You can probably detect my exasperation in the subject line...

I have a Denford Orac, converted to Mach3. I have an automatic toolchanger, which I've written a macro for which works perfectly to change tools. I have a limit / home switch on my x-axis (but not z). According to my indicator, this is very repeatable. I do the following to set my tool offsets:

1. Set x-axis home (causes the x axis to drive to the home switch)
2. Select tool 1 (a turning/facing tool), make a small facing cut, and select home z.
3. With Program Coordinates selected on the manual screen, go to tool offsets, and ensure there's a zero offset in the z-axis 'Part Zeroing Coordinates', then press touch z. Then out of superstition open the tool table editor, select apply and ok.
4. Back in the manual screen, make a small profiling cut. Measure the OD, then go to the Tool Table screen again, type that OD into the x-axis 'Part Zeroing Coordinates', and click touch x. The Axis Coordinates DRO at the top of the screen will show the OD I typed in. Again out of superstition I open the table editor and hit apply, then ok.
5. Select tool 3, a grooving tool.
6. Jog the tool until it's resting against the faced end (using roll-up paper). In the tool table screen, enter 0 in the z-axis Part Zeroing Coordinates DRO, press touch z. The Axis coordinates z value shows zero. Apply and ok in the tool table.
7. Back on the manual screen, make a small profiling cut, then job the tool along the z axis and measure the OD. Then enter this OD in the tool table screen exactly as described above.
8. Repeat steps 5-7 for other tools.
9. Now, to check everything's worked, I go to the manual screen, select different tools, then drive them up against the piece I've turned and check that the Program Coordinates show the right values (zero at the end of the workpiece, and what ever the OD was that I last turned. _Everything seems fine!_

For reasons that will become apparent I make a record of my tool table by going to Config -> ToolTable, and doing a print screen, and saving the image elsewhere.

Now, I go to config->save settings. Then I exit mach3,  which asks me if I want to save tool table values, to which I say yes.

Here's where things go wrong: I load mach3 turn again. I home my x-axis, and choose where I want z zero to be and hit Set Home Z. I type T0101 in to the MDI - the tool changer loads tool 1, mach3 says tool 1 selected. If I now drive the tool tip up to the chucked part, the value displayed in the program coordinates x-axis is totally wrong! E.g. where it should be 22mm, it'll show something miles off, like 40mm. It's the same story with the other tools. Where the offsets appeared to be correct, they're now totally off.

At first I thought the tool table values weren't being saved correctly, but if I compare the values to what I recorded (by doing the print screen as described above), they're correct. What's really strange is that if I go through the whole tool offsetting procedure (as described above), e.g. driving tool 1 up to a known OD (the same OD I had used when going through the whole palaver the first time), entering the OD in the part zeroing x-axis box and hitting touch x, mach3 will load a completely different offset in to the tool table than was there previously!!!

What the hell is going on? I've actually been at this on and off for about a month - I thought I had it licked, but today after another round of this nonsense I just came to the conclusion I have to give up and buy mach4 or go down the linuxcnc route. But before I give in I thought I'd see if anyone out there had any ideas?

Any help is really appreciated!



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