re:Re: gcode comments

Brian,

Excellent post! You have DEMONSTRATED what I've been saying!

It is EXACTLY the "switch" TO G20 and 21 for inch and metric which
has "freed up" their use for other things, as you have posted...

Likewise, the lower numbers (including 20&21) 'useta' be used for
things like 'long' coordinates, axis accel/decel params, multi-
quadrant arcs, etc. Better computing capabilities have eliminated the
need for such distinctions, freeing these numbers for other uses.

The 70's are currently being used to "extend the canned
cycles" 'downward' from the previously defined 80's... Brian is
right; these are currently "unsettled" codes,much like VHS vs. Beta
was in videotape. (some standards WILL evolve, IMO...)
The 60's are being used for "cutting modes".
The 50's are being used for different coord systems.
The 40's are used to handle tooling offsets/ wear compensations.
The 30's seem to be 'in-process' type things, like the probing
discussed earlier. (also a little "wild west-ish" at present)
As a group, the teens,20s,90s seem to be split across two or
more 'types' of usages/functions (per ten gcodes).
And the G0-G10 seem to be basic 'move types'.

Hope this helps.

Ballendo

P.S. The difference between LATHE codes and MILL codes is easily
accomodated when writing the CNC control. Simply add a Lathe or Mill
format codes? parameter. The two groups (Lathe vs. mill) definitely
went different ways with the (then) unused codes!

> > Example: G20,G21 are COMMONLY used nowadays for inch/mm
> > programming. Used to be G70,G71. For now I think
> > we should be 'backward compatible to 70 and 71, BUT we should also
> > support 20 and 21... There are LOTS of other examples!

> It's G20, G21 in the EMC's interpreter. Should G70/71 be added?

(Brians' orig post below)
sure but by what definition?
these are now commonly used on turning centers
G72 stock removal in facing
G71 stock removal in turning
G70 finishing cycle
they let you make several roughing passes leaving some stock
for the finish pass and then run a smooth continuous path finish
cut
the whole range of G7X has so many flavors that trying to enforce
any "Standards" on them would be like herding cats ;-)
Brian