Milling leaving behind "threads" of copper.

[spinnaker]

Posted this on the Flatcam forum but it doesn't seem to get much activity there so thought I would try here too:

I am milling PCBs. I am using Flatcam to produce the gcode and autoleveller to "level" the code. Over all it does a great job. But I am noticing what looks like "threads" of copper in between the traces. Typically the "threads" hug the traces. I can remove them easy enough with a scribe but the process can be tedious.

I am using a 30deg etching bit .1mm. I set flatcam so it overlaps 22% and I am cutting 3 bit widths.

Any one else milling and have seen this problem?

[Country_Bubba]

I have had this problem also, but it has boiled down to one or a combination of the following problems.
1. dull cutter (improper grind)
2. rpm of cutter
3. feed of the cutter
4. lubrication or the lack of it.

It takes many test just to see what works for you.

[spinnaker]

I will try bumping up the rpm. But I can't go too much higher. Have one of those cheap Chinese routers.

My blades are pretty new so doubtful that is it. But how often should I change out the blade?


Lubrication? I am not doing it at all. How should I lubricate?

[Country_Bubba]

I believe your using a "V" type bit so you need to turn it as fast as you can because the tip is extremely small and you need to get the cutting speed up.
Changing the tip will be a trial and error type of thing depending on how much you use it, quality of the tool to begin with etc. Look at it under a magnifying glass or microscope if you have one.

Lubrication, try spraying the board with some WD40.