[StirlingMachine]

Hi all, first time posting here. I saw there was another post from the last few days with a similar title, but the question seemed different and all the old threads with similar questions were years old, so I started a new one anyhow.

I just purchased a used Fadal VMC 40, '95 vintage. Spent most of yesterday getting up to speed with the machine, and was going good until I got to Z fixture offsets. My last machine had a centroid control that made part setup stupid easy, just say which tool was in the spindle and touch off and done.

Some background:

running format 2
using the UT command and the tool setting cycle for tool offsets off of the table with a 123 block.
Tool offsets are negative, ie, -15.xxx from CS Z zero position.

I think I may have it figured out, but wanted to get some other opinions before i send a tool out into the fray.

The way I had been thinking about it was this: Tool offsets are listed as negative numbers from CS Z zero, so in my mind that zero was the reference point. But if you want to touch off the part in the Z axis there isn't any way to specify the tool offset number while in the fixture offset routine, and if you set the readout to offset with an H# command in MDI and then go to the Jog mode it reverts to machine coordinate mode on the readout. And if I jog to the position and then punch in an H# command in MDI it tries to move to Z zero. So the number on the readout is totally relative to tool number and without an absolute to compare that to it is useless. So that way doesn't work.

So here's the root question: DOES THE MACHINE RECOGNIZE THE TABLE AS THE ZERO REFERENCE FOR FIXTURE OFFSETS EVEN THOUGH THE TOOL OFFSET VALUES ARE NEGATIVE FROM COLD START ZERO POSITION?

If that's the case then the math becomes easy, just subtract the number on the DRO readout when touching off the part from the offset value for same tool listed in the tool offset table. Then add that number in as a positive number in the fixture offset table. That should equal the distance from the table to top of work, is this right?

Any help is appreciated.

Cheers

[StirlingMachine]

So, no one know the answer?

[DareBee]

If your tools are zero at the table surface and your material is above the table, then your Z offset is positive the distance above the table.
No math required
The other posts you read are not as old as your machine and the answers are still the same

[StirlingMachine]

Thanks for the reply. Obviously nothing has changed, but I hadn't been able to find an explicit answer to that specific question. I think it was taken for granted in the explanations. But I think you could see how when the tool offsets are listed as negative numbers relative to CS Z zero, it could make you question what the reference was yes? Fadal manual was not exactly explicit on that specific point either.

Thanks again.

[jbranting]

I set all my tools in relation to CS Z0. I run two vmc 4020's all day everyday, just use the tool length as the z work offset basically. I just hit MANUAL, space, 5, and when it asks if you want to set the length of that particular tool you hit Y, easy as that

[mflux_gamblej]

pretty sure i already posted this doc before. its attached as a PDF. this is way back when I was learning fadal too. I have tool setting probes now though - I highly recommend it.