I’ve got a problem with the finishing of the carved edges in the mdf board- there’s always a visible rough stripe after the first pass. It doesn’t matter if the board is 10mm or 18mm thick. The rest of the passes is smooth and the problem doesn’t occur while cutting in plywood.
Any ideas how to fix it?
My guess would be that the bit can vibrate quite a bit during the initial pass but is more confined as it cuts lower and so does not stray as much.
To address this issue some people create a roughing pass that cuts a tiny bit outside of where you want your finished piece to be and then follows that pass with a finishing pass that cuts right on the edge. This does take longer but can produce cleaner results.