Not really sure what forum to post this in but I am running into an issue while cutting composite Norbond and AAR brand panels. These panels have .010-.020 thk fiberglass face sheets and a phenolic honeycomb core (1 inch core on these particular ones). The machine is a Thermwood router. Basically I can get about 100 inches or so out of a bit before it has a notch in it from the fiberglass. Once this happens it doesn't cut so much as just beds the face sheet up. At this rate I would have to go thru as many as 20 bits a day. What I am using right now are 3/4" diameter 2 flute up-shearing end mills. They are custom made in town and cost about $25 each. The guy says they are solid carbide but I kinda wonder about that because the price seems WAY cheap. Either way, I have cutters I KNOW are solid tungsten carbide and they dont last but a few thousand inches. I am running a spindle speed of 18k and a feed rate of 200 ipm. Anybody have any input on how I can make a bit last longer here?