Automatic probing?

[MagooT]

Hello.
I recently started using EMC2 and it seems really neat. However i'm a bit confused about the probing part.

I read about "Z-axis touch plate" for Mach3 and that seems like a really neat trick, could something similar be done in EMC2?

I have experimented a bit with the G38.2 command and it seems to work great for finding the top of stock, however could you add a button or something similar that would probe down and then automatically "touch off" Z? So i would be done automatically without entering the commands manually every time, or does that require modifying the source?

[samco]

take a look at
http://cvs.linuxcnc.org/cgi-bin/cvsw...e=text%2Fplain

There isn't a button per say - but you could create a gcode program that would set your tool length.

sam

[MagooT]

Thanks, i have played around a bit with that file, however it doesn't "touch off" the Z (is that even possible to do simply with g-code?), and also it doesn't seem to be possible to probe while the program is paused (for manual toolchange).
That's really what i would like since i have to change tools manually and getting the height right is rather difficult.. any hints how to do this?

[samco]

that is one of the things some people don't like about emc2. You cannot pause a program and jog/touchoff or such and then unpause the program. If you want to set tool lenghts/touchoff - it will have to be done before the gcode program is run, separate gcode program or within your gcode program.

Or... you can modify emc2.

sam

[cyclestart]

The file samco provided seems to assume a fixture z offset is already in place using some tool as a chosen reference. Then does the other tool offsets by writing to the tool table while the program is active. Am I reading this correctly ?? Very cool if it works as expected. Anyone here tested this?

MagooT

I don't know if a probe type move can write to a fixture offset directly. Maybe after some more coffee.....

edit/ On rereading it looks like the modified tool length is stored temporarily, not in the tool table. emc certainly does some cool tricks!!

[MagooT]

Ok thanks for your replys, i will play around with it some more.

[samco]

The link I sent - set tool length (best way I would think). There are a few way to do it. I have also done it by setting the g10 (g54..) offsets. It works also but the axis preview is a bit off (shows the cut path is different from the preview path).

dynamically setting the tool length is better as axis will show the preview correctly.

the way I have it setup for circuit board milling is this.
I have a microswitch mouted to the table and every time there is a manual tool change - the gcode program (after I change the bit) goes over to the micrositch and sets its touches off. I then do the math and set the current coordinate system. (again - all in gcode)

The link I set is a better way to do it using tool length.

sam