[davecaswell]

I'm having problems routing out PCBs. Sometimes it works well, and sometimes I get really ragged edges on the copper. All settings were the same when I milled the top and bottom sides of the pictured PC board. The top had nice smooth edges, but the bottom came out with little sawblades on the edges of the copper. This was with a new 30 degree V bit from Think and Tinker.

[Riceburner98]

Any chance one side was climb milling and the other conventional?

[davecaswell]

Any chance one side was climb milling and the other conventional?

Check out the image of TnTs' Mechanical Etching Bits on this page: Product - Carbide Mechanical Etching Bits

I'm not sure climb milling makes a difference with bits like that.

I will look at the g-code and see which way things were moving for sure.

[Riceburner98]

I don't know if it would make a difference or not, just throwing out a guess. I've never used a V bit for circuit boards, I've always used conventional (tiny) endmills.. Less chance of snapping a V bit though I'd guess.

[SignTorch]

The attachment shows a pcb milled with the same bit, it has no burring, and the cut is smooth and shiny. It was done with a porter cable laminate trimmer with new bearings and a homemade bit adapter, with almost no runout.

You must just barely cut through the copper, you shouldn't get hardly any dust from the epoxy laminate, it will dull the bit.

You must have a tight spindle with < .001" runout (the bit tip is .0005" across the flat). Runout and vibration will kill the bit. Definitely can't use a dremel tool.

The bits outperform endmills 100 to 1, they last a long long time, and won't break as easy as a small endmill. But once you start getting burrs, then it doesn't last long, probably due to heat build up.

I usually try to make a conventional cut on the finished edge but never really noticed any problem from climb milling.

I'd say your bit is definitely toast, once you push a burr like that it's no longer cutting, it's just rubbing the copper out, and getting hotter and duller the whole time.

If you have runout, it will quickly dull one side of the bit and it just won't cut right.