Thanks for your replies. I did try slowing the rpm down to 10K at which point the router was stalling, but no difference. Yes, of course I meant inches per minute! The system was tramming previously, but I fixed that and the surface is now completely smooth to the touch - the main scorch marks are on the point where the bit is making the cut. As it surfaces perfectly with a 1/2 inch router bit I am inclined to think that the Amana bit has dulled, which for an expensive bit is disappointing, after just 4 uses. My Machine is an Oozenest WorkBee. Max speed is 2500 mm/min, which equates to 98 ipm, so I am thinking that this is just the wrong bit to use with this machine, however running at 15000 rpm and 98 ipm would give the same chipload to that recommended.