Here's my thinking;algale wrote:...
Second, I'm not router savvy enough to follow all of this. Why do you think the first router bit broke? And why would a 1/4 inch shank, 1/2 inch diameter bit do better in the higher RPMs of the OPR than in the PP at lower RPMs? Intuitively, I would have thought the opposite, but again, I'm a router ignoramus.
Why did the tip of one blade in the 1/2" (w/ 1/2" shank) break? Who knows! Nothing happened that gave me a clue. Maybe it was too brittle, maybe it got dropped and I don't remember. The break was just the tip of one of the two cutters in the bit.
Spinning at 10,000 RPM with one tip missing gave me only 5,000 rpm for digging into the wood. This gave a rough routing experience. It caused the wood to chatter wildly.
Needless to say, 22,000 RPM produces a smoother/faster cut than 10,000. The narrow, 1/4" shank will break a lot easier than a 1/2" shank. Pushing a bit with a 1/4" shank does cause breaking. (experience
) Therefore with a faster cutting bit I could feed the wood slowly without the shank breaaking (I hoped). Feeding a piece of wood as heavy as the bench top across the table gave me pause because it was real hard to tell how much of the resistance was from table friction and how much was from cutting resistance. The faster cutting bit reduced resistance from the bit. Still I took shallow passes until reaching 1 1/2" depth.
