Re: [CAD_CAM_EDM_DRO] re: EMC coordinate systems

ballendo@... wrote:

> <snip> or is there a G code I can send to set the diameter
> of the cutting tool? Will EMC move the tool exactly on the coordinates
>
> in my NC file (implying that I need to generate NC with a tool
> diameter offset), or can I tell it the installed tool and have it
> account for it. (I'm guessing that I need to give it the exact path
> the tools should travel, and I (or my NC software) needs to account
> for the tool travel.)
>
> Any control with G40,41,42 properly implemented will account for tool
> diameter when cutting on the XY plane. G43/49 is typical for tool
> length compensation.

This gives you the FACILITY to do cutter radius compensation and/or
cutter
length compensation. But, it is not completely automatic. length
compensation
doesn't require much preparation, just to be sure that the moves when
the length
compensation is turned on or off will not cause the tool to crash into
anything, as
it will make an abrupt Z axis move equal to the difference between the
previous
position and the length offset.

Radius compensation requires significant preparation, as there needs to
be a
(generally linear) move over which the radius compensation is
interpolated in
(or out). The tricky part is that most controls require that all inside
corner moves
done under radius compensation have a radius greater than the tool
radius.
This generally requires you to place artificial starting and ending
points
either somewhere inside a pocket or outside a part (for exterior
machining)
for these "lead-in" and "lead-out" moves to be made from/to. Correctly
choosing these spots will prevent the control from rejecting the move.
No low cost package that I've seen handles this automatically.
Once you've done it a few times, you get the hang of it, and the control

takes it the first time.

See http://206.19.206.56/diacomp.htm and
http://206.19.206.56/lencomp.htm
for some help in how to do this. These are in the CAD_CAM FAQ.

Jon