10-23-2016, 04:13 PM
I usually switch over to HSS tools to rough out jobs like that, then switch back over to carbide to do the finishing passes.
I use a roughing tool grind that I saw on Adam Booth's channel, but can't seem to find it.
It's flat on top (i.e. no top relief), has some front relief and side relief (actually, not much, only about 5° to create a strong cutting edge) and a small 45° chamfer with relief on the leading corner of the tool to keep the edge from breaking down. He also cuts a chip breaker into the top using the corner of the wheel. The chip breaker doesn't come to the edge - it's about 1/16" back from the edge. I believe it works to chill the underside of the chip, making it break.
It's a beast of a tool - I've cut .25" DOC (1/2" diameter reduction) on mild steel with it. It requires not only a short grip on the work, but also a shoulder bearing against the chuck jaws or it will just extrude the work through the jaws. It also requires lots of lube, some HP, and low RPM for a big cut like that.
I use a roughing tool grind that I saw on Adam Booth's channel, but can't seem to find it.
It's flat on top (i.e. no top relief), has some front relief and side relief (actually, not much, only about 5° to create a strong cutting edge) and a small 45° chamfer with relief on the leading corner of the tool to keep the edge from breaking down. He also cuts a chip breaker into the top using the corner of the wheel. The chip breaker doesn't come to the edge - it's about 1/16" back from the edge. I believe it works to chill the underside of the chip, making it break.
It's a beast of a tool - I've cut .25" DOC (1/2" diameter reduction) on mild steel with it. It requires not only a short grip on the work, but also a shoulder bearing against the chuck jaws or it will just extrude the work through the jaws. It also requires lots of lube, some HP, and low RPM for a big cut like that.