I am doing a little work in Eagle to validate my CNC setup with a 60 degree 0.2mm vbit. I have laid out a series of traces and then incremented the trace size. The traces are 50mil (0.050") on center. The left most trace is 1mil (0.001") and they increment to 25mil (0.025") on the right. The bottom trace on the horizontal axis is a 30mil (0.030") trace.
I am going to see how accurately I can reproduce this test. I expect my isolation cuts to be about 12mil (0.012") with my 60 degree 0.2mm vbit. My expectation is that any of the electrical traces smaller than ~10mil (0.010") are going to be wispy and unreliable with my CNC and cutting bits.
If this test works I will use it to test the new bits that are on order and should arrive this week with some luck. Once I have all of this testing complete I will build a reference document for these tools. That should mean that I can work on single sided prototype boards. --Dual sided boards are research project for another day. ;-)
The garage is heated up so I am headed out there in a few minutes to fire up the CNC mill.
73 de NG0R