Pcb-gcode question Bug?

[Drools]

I have been tinkering with the isolation settings on my PCB layout and I'm getting a weord result with some settings. Maybe someone here can shed some light on what is happening.
Here is a picture of my PCB layout in Eagle notice the USB connector hangs out over the PCB mill outline. This is where I'm thinking the problem starts.


Notice the PCB-Gcode output it adds an etch line outside the milling outline. It only does this when I set the: Isolation-->Maximum > .01. Under .01, I do not get very much isolation but it does not add this extra milling.


Doing singles on scrap pieces of PCB this is fine however if doing a dual board side by side I then have to waste the extra PCB material.
It would be nice if when determining the gcode, pcb-gcode would do a check for the milling outline and stop if there.

[Jay C]

Word of warning. Make your milling outline the same size as the bit you will be using to cut it. That way you can see if you will be slicing into your pattern, which I suspect you will be like this.

As for the extra outline, I've never seen that before. Does mach3 show that same outline?

[Drools]

yep, Mach3 shows the extra outline. I will post the question on the pcb-gcode forum.

[pminmo]

Simple answer is to edit the gcode to remove the second outline. Is it in the mill gcode file or the isolation gcode?

[Drools]

hi Phil, the extra outline is in the isolation gcode. That just makes it a little harder to find and delete.

[keebler303]

One thing you might try is to hide the layer with the component outlines. It looks like PCB Gcode is just finding the smallest rectangle your layot will fit into and then generating milling within it. If hiding the layer doesn't change it, you could always edit the component layout so that it didn't overhang the board.

You can use mach3 or ncplot to find the lines of gcode, both will highlight the line segment corresponding to the line of gcode you select. Pay attention to what Jay C said, PCB Gcode generates milling paths based on the centerline of the board outline, NOT outside it. If you use a cutter bigger than the thickness of your outline, it will cut into your board.

Matt