Re: [CAD_CAM_EDM_DRO] emc g92

ednass01 wrote:

>
> i have the emc rc46 bdi on a small lathe. i jog the machine into
> position and make the first cut. i then measure the part and set the
> machine position with g92. this does not seem to work for me. i have
> searched the web and found a lot of references to g92 and g54-g59.
> maybe g92 does not work on my machine or maybe i am confused. how can
> i reset the position in emc to match the position of the tool bit?
> thank you

Hello,

Several months ago I tried using EMC. I ruined some parts due to G92 not
behaving as it does for TurboCnc. I wrote to the EMC users and
developers lists and they basically told me that I needed to find
another way to set the axis values. They pointed me to a 20 page paper
(http://www.linuxcnc.org/dropbox/g92test1.pdf) explaining all the weird
things that happen when you use G92 but also claimed that this is the
way it should behave. Anyway, because G92 does not work and because I
have no way to set the axis values within a Gcode program I have not
been able to use EMC.

Another respondent to your query suggests that you use the mouse to set
the axis values. Requiring that you be prompted by your Gcode program to
type in known values is absurd.

I use G92 frequently within my Gcode programs. Gcode prompts the user to
load a bit and touch the surface. The user jogs the bit until nearly
touching the surface. Then loosens the bit so that it drops down and
touches the surface. The user then tightens the bit just enough so that
it won't fall out. The next instruction is G92 Z 0.000 or whatever value
that I want. This is followed by G00 Z 0.040 to raise the bit a little.
Then a prompt to the operator to tighten the bit and start the spindle
or set the spindle speed to 1000RPM or whatever. Then the program
resumes operation.

I gave up on EMC and use TurboCnc primarily because I have found no way
to reliably set the axis values from within a Gcode program.

Tom Hubin
thubin@...