Re: Re: Re: Need G Code help

From: EdFanta <atex57@...>

> Subject: Re: Re: Need G Code help
>
>
> Ok Guys, I'm completely lost. I will ask if someone can write a bit of
> code to get me started. The pocket in question has been programmed and
> works EXCEPT for the first corner. If I put a negative radius for the
> first R word it gives a funny loopy corner, comes back to the end point
> of the radius and completes the rest of the pocket just fine. I am
> starting from x0y0to a pre drilled hole at x10y2, the z goes down and
> mills to x8.9y3.25 then a .75 radius to x8.15y2.5, a straight cut to
> x8.15y1.5 then a .75 radius to x8.9y.75 then simular to the other two
> corners to return to x8.9y3.25 All co ordinants are to the outside of
> the pocket.I am using a 1/2 endmill which is called out as T1 in the
> tool file, am using G3 and G41 to climb mill in the corners. If some
> helpful soul can write a little code to get the first corner done and I
> can see my mistakes I would be grateful.  After it is all figured out I
> can post with the postmortem. Ain't lernin fun??? Thanks.   Ed.

Ed

You gotta understand that the problem is the point between the line you
drew immediately before the arc and the angle of the start of the arc.
The angle there is less than 180 which means that the EMC will refuse to
push a cutter of diameter greater than 0.00 into it! When you reverse
the r then it makes a 3/4 bulging arc and the angle in question is
greater than 180 so it has no problem saying to itself, "I can do that."

If you have to start at x10 y2 'cause that's where the hole is, you
should make your first move to x10 y0. Then bring in comp and move to
x10 y2. Now you should be over the hole except that it will be offset in
x minus the radius of the tool. Then move z down. (Yes Fred we can do
that with the EMC.) Now move the tool plus y to the point where the
closest arc starts. From there it should work okay.

You didn't say where that farthest finished x edge was so I'll assume
that it is really at 10 inches. (I suppose that it could be at 10.250
since that is where the edge of the tool starts making the pocket.)

n100 (Ed's pocket program with tool offset)
n101 g0 x0 y0 z0
n110 m6 t1
n120 x10
n130 g1 f10 g41 d1 y2
n140 z-0.25
n150 y2.50
n160 g3 x9.250 y3.250 r0.75
n170 g1 x8.90
n180 g3 x8.150 y2.50 r0.75
n190 g1 y1.50
n200 g3 x8.90 y0.75 r0.75
n210 g1 x9.250
n220 g3 x10 y1.50 r0.75
n230 g1 y2.0
n240 g40 g0 z0
n250 x0 y0 z0
n260 m2

If you want more, contact me off list and I can send you a picture of
what you were trying to do and where it fails.

Ray