Re: Newbie: G Code Programming Question

Alan,

Thanks, I do use the lower left corner because that matches how I
usually measure locations on parts from drawings.

Do you use the origin point at the center of the spindle or the edge
of the cutter when writing G-code?

I purchased Dolphin Partmaster/CAD but haven't looked at it much so
I don't know if it has cutter compensation. I'm trying to learn to
program directly in G-code first as a base, then I thought I would
tackle the huge CAD learning curve.

Thanks,

George

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Alan Marconett KM6VV
<KM6VV@a...> wrote:

> Hi George,
>
> For normal coordinate location (for us hobbyists), the LL corner

is a

> good choice. This is quite often the way the part is drawn.
> Occasionally, as for cylinder end covers, the center works out

good.

> I'd start out at the LL corner. If necessary, the other corners

can be

> used as well. If I use my vice aligned with the Y axis, I like to

touch

> off on the fixed jaw, which is aligned with the X axis, and in the
> rear. Just don't forget which axis the drawing is made to. Bad

things

> happen if the coordinate "frames" don't match!
>
> For tool radius compensation, first draw the part outline, then an
> "offset" around the part is drawn. Programs like Vector CAD/CAM or
> similar make this easy. Perhaps your CAD software has this. The

offset

> should be 1/2 the dia of the tool.
>
> HTH
>
> Alan KM6VV
>
>
> gglines1 wrote:
> >
> > I'm just starting to CNC program in G-codes. I'm uing MillMaster
> > Pro for Windows by Microkinetics on a mill/drill.
> >
> > My software doesn't have tool radius compensation and I'm looking
> > for advice on how to approach programming toolpaths. I hope I

can

> > explain this clearly. I'm finding calculating the cutter

waypoints

> > tough.
> >
> > Should I CENTER the spindle on the workpiece origin (0,0) or the
> > EDGE of the end mill on the workpiece origin 0,0? For example,

let's

> > say I have a 1" x 1" (I'll ignore Z) workpiece with a 3/4" end
> > mill. If I set the center of the spindle (using absolute mode)

on

> > 0,0 (front left corner of workpiece), then I have to reposition

the

> > spindle by -.375 in both X and Y or half the distance of the

cutter

> > to get to the edge of the workpiece. The second way I could do

it

> > is to move the cutter to X-.375 Y-3.75 and then initalize that

point

> > as the origin (0,0).
> >
> > Any suggestions on which way to approach this?
> >
> > Many thanks,
> >
> > George
> >
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