Hello. I have a Shopbot PRS Alpha with a spindle router. I laminated together a 2" stack of masonite (hard board) with wood glue. Whenever I try to mill into this material with any of the 1/2" bits displayed in my attachment, they tend to slip in the collet (no matter how tight I wrench it) and pull themselves into the material digging themselves a nice unplanned trench. I have tried slowing my move speeds and it helps but it still can happen. I noticed the two bits on the right have a flat spot on their shank, and I thought that this was allowing poor gripping in the collet, however I tried the bit on the left with the smooth shank and it still did the same thing. I have been using a straight fluted 1/2" bit that works good, however it is not long enough to cut through 2 inches of material. I have been using a single fluted upcut 1/4" bit to do the cutting, but its barely long enough and I am constantly worried it will break. Any suggestions?
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