To clarify more about cutting .15" deep...

Oops, memory came back. I'm cutting .2" deep.
Yes, I am clamping a 12"x3"x1" piece in the vise, and philbur is right I'm sure that it'd do better clamped to the table. Also, note that I'm doing full slotting at 27ipm 4500 rpm with .2" DOC. That's something like a 0.5HP cut. I found it unreliable to try and do .7 or .8HP cuts 4500rpm. If anything isn't right- your cutter sharpness, recutting chips, etc, you'll stall the motor. There is a lot of discussion on here about what RPM gets the max HP from this machine. Also, I'm series 1 without the spindle drive upgrade.