Homebrew PCBs

At 12:39 18/04/2002 -0500, you wrote:
>One minor problem I've found with KCam is the lack of tool path offset, the
>cutter C/L now follows the edge of a design element such as a trace or pad.
>The larger your cutter, the smaller your pads and traces are going to be...
>which may not be a problem unless you want to do a tool change and use a
>larger mill for quicker and larger isolation areas on a board that also has
>some tight spots.
>I've exchanged E-mails with Kelly and he is working on including tool
>offsets in a future version KCam.

The trick is to generate the toolpath with the necessary offset built in. 
If you're working from DXF files generated in a CAD system, there is 
usually a means of generating lines/curves offset at a known distance from 
existing lines/curves. I do a lot of work using drawings generated in 
AutoSketch, and import them as DXF into Supercam, which also has no tool 
path offset capability. What I do is to draw the object actual size, then 
create a second drawing, in a separate layer, using Autosketch's line 
offset capability, with the offset set to 1/2 the diam of the cutter I am 
planning to use. It is a bit of a PIA if you then decide to use a different 
sized cutter, as you have to regenerate the toolpath, but it has worked 
well for me so far.

More sophisticated CAD/CAM, such as Dolphin for example, will take a DXF 
drawing and automatically generate G-code for the toolpath with allowance 
built in for the cutter diam if need be (i.e., by changing the coordinates 
in the G-code moves themselves, rather than relying on the CNC control to 
compensate on the fly).

Regards,
Tony