Manual tool change + tool lengh touch off

I'm trying to find a solution for manual tool change. In my opinion it should work so:

I've a switch at a defined position in the mill-area. If i start a milling progress my milling machine goes to the defined position and drives the tool against the switch (in Z-direction). Then Axis knows the Tool offset. After a manual tool change Axis runs the same procedure.

So far I've to less experience with emc to know how or why not this would work.

Is it possible to do it only with an instruction block in the G-code? Or do I have to Change somthing in the HAL?
Would it be possible to abuse the Z-Axis home switch and just run an "home instruction" every tool change?

Axel

Hi

Thats exactly what I'm looking for since long time.
I was wondering if such functiuonalty is connected to the probe input ?

THX Mike

andypugh wrote:

EMC2 can do a Z probe from a G-code instruction and store the result in a memory location.
G-code can use the value in that memory location to set the tool length.

So if you know these things, wouldn't it be enough to write a gcode-instruction-block and for e.g.copy paste it to every tool change in my*.ngc ?
Or ist it impossible for the gcode to route to an absolute coordinate of the mill machine?

If anyone has any code exaples i would like to experiment with them.

Not an very constructive post: But i found a nice Video how this could look like if it would work

andypugh wrote:

What I am not sure how to do is to make it all happen automatically when you issue an M6 command.

I think this should/could be a job for the postprocessor.

Has anyone experience with touch off probe hardware:
-Just a normal switch (could be unprecise)
- an induktice switch ( I could imagine that the induction is influenced by the size of the tool?)

So far I installed a touch probe and started experimenting with the gcode. But there are some errors I can't cope with:

If i follow the tool-length-probe.ngc example i touch of with

G38.2 Z0 f50 (f50 is modified)
when I try to run
G91 g0Z.2 (off the switch) I get the error:" Probe tripped during non-probe MDI command"

This could be solved by running the probe slower (f30) but if I want to have a big safety distance this could take a long time
Is there a better command to release the switch that ignores that the probe is pressed?

Second Error:

I touched of my tool the first time, joged a bit with the manual control, changed the tool length and run a G30. If I try to touch of again(G38.2 Z0 f30) I get "Startpoint to close to probe point"

Ok, I found out that G38 need to be run in G90 mode. But even if I try to release the switch with G38.5

Code Target state Direction Signal Error
G38.2 Contact Toward workpiece Yes
G38.3 Contact Toward workpiece No
G38.4 No Contact Away from workpiece Yes
G38.5 No Contact Away from workpiece No

which shouldn't cause an error, I get one