Inventables Community Forum

Troubleshooting PCB milling

I’m getting back into PCB milling on the X-carve. Below are two results that clearly need improvements; however I don’t quite know what the problems might be.

First: 0.7 mm endmill from Adafruit

Second 30 degree 0.1 mm engraving bit from Inventables

In both cases, I’m using the Dewalt 611 router with a precision collet, lowest RPM that the 611 allows, 5 inch/min feed rate, 1 mil depth of carve.

Granted, there are issues with the design itself (the profile toolpath incorrectly connects the pads). I’m looking for suggestions on the following:

  1. The 0.7 mm endmill can make nice profile cuts (see the middle left pads and traces); however, the majority of traces grab the copper (proper term here?). Additionally, as seen in the top of the first image, traces are not consistently the same size (both of the horizontal traces should be 16 mil).
  2. The 30 degree engraving bit provides much cleaner profiles. It may not be apparent given the resolution of this image, but there is still a fair amount of “ugliness” in the trace which may just be cosmetic.

It’s mostly academic, since I can probably get what I want done with the 30 degree engraving bit, but I’m wondering what I might pursue to improve the performance of the 0.7 mm endmill.

How’d you generate the toolpaths?
What was your feedrate for the 0.7mm endmill?

Toolpaths are made by importing a DXF generated by Eagle into V-carve. The feedrate for the 0.7 mm endmill is 5 in/min.

That seems REALLY slow. You’re melting the copper away. Any reason you went so slow?

I’ve broken bits at higher speeds, cannot find decent examples (most of the threads I’ve found say “just google this/that forum”), so I found a feeds & speeds calculator and extrapolated the data provided to the smaller size of PCB endmills.

That said, it’s clear that I don’t have the feedrate optimized and was planning on doing some additional runs at incrementally (~ 10%) higher feed rates unless I can get better data from the community here.

What endmill? Can you give me a link?
Are you sure it wasn’t a drill bit?
I have a Carvey here asking for me to cut a PCB.

Definitely an endmill: https://www.adafruit.com/product/2074

It’s possible that I’ve already dulled the endmill since the first bunch of tests I did dug deep into the FR-1. I did check under sufficient magnification that it isn’t chipped.

I use the .2mm 30 degree bits from Amazon that run 1.50 each. I have found they are only good for one circuit board or I start getting ragged edges because I am using FR-4 copper board. I run at 60 mm per minute when cutting the isolation routing. I use Flatcam to convert the Eagle drawings to Gcode to import into Easel.