I have been trying to mill a 1/4" dado in hard maple 3/16" deep. A couple of days ago I asked about "climbing" bits as my onsrud spiral cutter was coming out of the router. Followed the advice ftom several folks on the wreck and all went well....... exect that I broke the router bit.
I then switched to a a second 1/4" bit, this time a two flute carbide tipped straight cutter -- broke it as well after about 4 linear feet of milling.
Both bits snapped right at the collet so the whole bit broke, rather than just the tip.
now admittedly the second bit was not top of the line (it was from rockler) but to have two bits break doing the same operation in such short amount of time seems a bit weird. Both bits were 1/4" shank. I have been unable to locate a 1/2" shank witha 1/4" straight cut -- 3/8" seem to be as narrow as 1/2" shank bit go.
I was doing this in a router table with a PC7518 router mounted in a PRL. My feed rate was reasonable, _maybe_ 1"/sec
Anybody else had this problem -- I'd like to do some thinking before I head back to the shop and snap another bit !