Cutting black MDF issues

[Gary Campbell]

Rundover...
Can you verify which router or spindle you have and what method you use to change the RPM? What CAD/CAM program are you using to develop your toolpaths?

[Rundover]

I have been cutting the last of the sheets at 12,000rpm, 3"/sec, and added a 3 second pause before the plunge which had the best results. I was getting about 15% clean cuts before they started going bad but the bit would last cutting the whole sheet. Interestingly my shop manager accidentally set the Z zero 1/4" too low and was cutting into the spoil board but the sheet cut clean for 80% until the bit broke. So somehow the MDF spoil board was cleaning the bit on the way down.