Re:Gcode

Alan wrote:

>Download FlashCnc's control program, can't cut metal without the
>signal generator, but no restrictions, and you can "eval" it to see
>what gcode "should" do! No heli- cuts, what's that, anyway? Does
>do G02,G03, "canned" and others. I believe you can download the
>manual also (big point). A little looking around may turn up a
>control program (demo) for a top end $$$ program that you can use to
>"test" your code.

Alan,

I mentioned previously to try a D/L of Vector or Bobcad, of course
the more expensive programs also have demos.

A helical cut is very useful when milling. Means you dont try to
"drill" with an endmill designed for side cutting. MUCH less strain
on your machine! Especially important for the small sherline and
others which do not have the rigidity of full-sized machines. Helical
cuts allow "threading" moves to be done on cylinders sticking out of
a part, or more commonly, to internally mill threads into a hole.
VERY useful when you dont have that tap size and the part won't fit
in the lathe!

Flashcut's manual IS very good. Ron said he copied microsoft docs (go
figure) But it is clearly written.

>Anyone have a few lines of gcode that demonstrate cutting arcs in
>the other planes? Like, when do you do that?

Okay:
G0 X0Y0Z0 (keep it understandable, we'll start from zero)
G90 G20 (absolute coordinate system, inches)
G18 (select plane XZ for arcs)
G02 X10 Z10 I5 K5 F25 (CW arc from 0,0,0 to 10,0,10 f/rate 25IPM)
M01 (stop if operator has the optional stop switch on)

This might be used to round the side of a left front fender on a
model car.

Another:
G0 X0Y0Z0 (as above,KISS)
G90 G21 (absolute mode helps prevent beginner mistakes, millimeters)
G19 (select YZ plane for arcs)
G02 Y10 Z10 J5 K5 F25 (CW arc much smaller,mm's remember F/r mm/sec)
M02 (stop)
This arc takes place around the corner (A LOW front bumper??! :))
It is not possible with many machines to switch between inch and mm
during a program.

>A "curved" bottom >pocket and a ball end-mill??

Yes!,We'll just do the first move:

G0 xoyozo (caps doesn't matter)
G90g20G18 (spaces don't either,but some ctrls wld not allow multi G's)
g01F25 (set 25 InchesPerMinute, is modal so not needed next line)
G03 x2y0z0 I1 K-.25 (this will take ballmill to x2, max 1/4inch deep)
M30 ( stop and rewind to start, for next part)

Comments in gcode are in ().The control ignores them. G03 is CCW arc.
If the G03 above was changed to G02 we would not cut anything! Just
make most of a circle above the material, starting and stopping at
the material surface. (Like tracing a hula-hoop buried partially in
sand.)
All snips above assume part surface is Z0.


Hope this helps

Ballendo