Troubleshooting Fray in the Cut

Advice on bit choices to eliminate fraying in the cut on a CNC. August 16, 2012

Question
I'm using a new plywood (at customerís request ). Itís a 19 mm c2 prefin both sides with 7 lams. Three-four are fir and the others are definitely not poplar. I've tried different feeds and speeds on about five sheets and I cannot get it to cut clean. I am encountering rough edges even with two passes around the exterior. Has anyone ever had this problem? Iím using carbide compression and downshear.

Forum Responses
(CNC Forum)
From contributor Y:
Reverse the direction of the travel of the router bit.



From contributor H:
Have you tried doing a first pass in a climb direction while offsetting the bit 1/32", and then following with a conventional pass to final size? If not, see if that will help.


From contributor M:
Before going too crazy, how many flutes is your bit and are you on a spoilboard or pods? I have run into a lot of similar issues at times, but nearly always have solved them with a very sharp bit run at the proper feeds and speeds.


From contributor B:
I know that spirals are generally better and can cut faster, but the simple fact is that straight cutters leave a far cleaner edge than spirals. Try switching to a straight bit.

From contributor G:
You need to use a 3+3 ruffer/finisher. That eliminates all fraying. The chipbreakers break up the chips quicker. Feed speeds vs. rpm's are provided so the chips will be evacuated and not re-cut.