I am trying to rout a simple slot with a 1/4 inch MLCS straight router bit, and the bits keep breaking! The first one broke across the carbide insert after routing several mortises into end grain in cherry. I was making a half inch deep cut all in one pass. After replacing that bit I cut the endgrain in two passes, 3/8 inch deep and then 1/8 inch deep to finish. I cut five of these and then switched to routing 1/4 inch deep slots along the grain. While doing this, the second bit broke. The failure was at the bottom of the carbide insert this time. I am using a Ryobi RE 600 router mounted in a Bench Dop Pro Top. I had to run the RPMs up near the top of the range to keep the end grain cuts running true. What am I doing wrong? Thanks.