Chris Radek schrieb:
> Hi Sven, I've added this scheme to the emc2 cvs trunk. I can't test
> it right now but maybe I can set up something one of these days.
Cool thanks.
It will probably take another week or two until I have a controller for
my machine that EMC2 could work with. And probably another week or two
until I figured out how I need to set up EMC2 to control my machine.
> G43 with an H index -1 is now a "transient" tool whose offsets are
> specified on the G43 line. The length offset is specified with the K
> word (and X offset with I word for lathes).
>
> So G43 H-1 K0.5 would do the same thing as G43 H3 if tool 3 has a
> length of 0.5 in the tool table.
>
> Like I described above I think this will let you use probing to
> measure and set up length compensation for a newly inserted tool in a
> fairly straightforward way.
>
> (Since H-1 was previously disallowed, this will not break any
> existing programs.)
Hmm, looks useful, especially if I can call a subroutine upon each tool
change. Speaking of subroutines:
What I would find highly useful would be if emc2 provided
1) Access (read&write) to the tool lenghts in the tool table
2) Access to the currently selected tool identifier
(read-only, use T-word to change it)
2) Access (read&write-once) to the currently set reference tool index.
3) (optional, though ideally available): A way to define that
subroutine X (a G-Code program) be called on every tool change.
With that, I could define a subroutine which does the following (sorry,
don't know the G-Codes right now, not even wether the conditionals are
available, so I'm using C-like pseudo-code):
idx=cur_ref_tool_idx;
if ( idx==0 ) {
cur_ref_tool_idx=cur_tool;
}
if ( tool_length[cur_tool] == 0 || always_reprobe ) {
execute("G00 Z0");
execute("G00 X probe_pos[X] Y probe_pos[y]");
tmp_length = result_of(probe_length);
if ( check_tool_lengths
&& ( tmp_length!=tool_length[cur_tool] ) )
{
abort("Tool length inconsistent for tool $curtool");
}
tool_length[cur_tool]
}
execute("G43 H-1 K tool_length[cur_tool]-tool_length[cur_ref_tool]");
return;
Or in other words: A routing which checks wether a reference tool is
already set. If not, use the current tool index to set it. If the
current tool length is 0 (no previously set), set it to the value
returned from probing at position probe_pos (note: We have a rather
large (regarding our tool sizes), completely even area where the tool
can hit for the probing. Therefor the actual size and shape of the tool
are of minor interest to me regarding this probing.) Finally: set
effective tool length offset to the difference of recorded "lengths" of
the reference tool and the current tool (which might be the same and the
"formula" might need a different prefix - i.e. tool_length[cur_ref_tool]
- tool_length[cur_tool]).
Stuart Stevenson wrote about a machine that verifies tool lengths to
mitigate the posibility of broken tools or wrong tools. This would be
achieved with the above subroutine if always_reprobe and
check_tool_lengths are both true. Machines with no tool changers would
set always_reprobe to true and check_tool_length to false. Machines with
tool changers could set both to false and still automatically populate
the tool table with determined tool lengths.
Geeze, would be great if this could be implemented.
Of course, it would be even greater if it was directly available inside
EMC2 with no special requirements in the g-code except for the usual
"M06 Tx" to select tool x.
BTW: Can I tell EMC2 to automatically go to a specified position on M06
execution so that I could change the tool manually, waiting for
confirmation from me? I might have overlooked it, but I couldn't find
this information in the docs (yet).
regards,
Sven
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