Monthly Archives: August 2014

G-code fixing tool

The plugin for Eagle PCB CAD called pcb-gcode is great, don’t get me wrong. But somehow it wants to start the coordinate system so that the X values are negative. Also it made some strange “margin” in Y-axis which makes alignment of the actual PCB to be milled difficult.

So I wrote a tool that can:

  • automatically translate the axis so that there is no negative values
  • automatically detect the actual “working piece” (values with negative Z) and use the working area’s “zero” as actual workpath zero. This way you can set the home to zero at the physical location where you want the mill to be started.

See this picture for the original gcode generated by the Eagle ULP:

Näyttökuva 2014-8-19 kello 22.24.07

And then gcode my program generated, reloaded back to the software itself (the green cross indicates gcode x+y zero point). The toolhead still visits to negative Y-values at the start but that’s too difficult to be removed (see the line that goes to bottom right corner):

Näyttökuva 2014-8-19 kello 22.23.18

Fourth milling: Drilled PCB

First attempts! Not perfect but usable.. The PCB moved alot in Z axis.. Traces are 0.4mm – or try to be. That’s probably the safe minimum. Full board size was 71.6mm * 100.2mm (note to self). I used this bit – a 90 degrees 0.1mm V-shaped bit. Drill size was 1mm, should use 0.8 or 0.6mm size drill..




Second milling: Finger joint plywood box


My first adventures in the land of CNC milling was to make a wooden box. I’ve always liked boxes, finger joints and computers. Don’t ask me why.

However the problem with CNC milling is that inner edges tend to come round – for some strange reason. On a finger joint it causes problems; the pieces won’t go to the very end of the joint.

I overcome this by making a little “notch” at the inner edges (see images below). So I wrote a PHP script that generates a PDF that I can use when generating toolpath for the machine. Now I can make different size boxes with just changing few parameters!




Näyttökuva 2014-8-13 kello 20.57.27