We size our RP cabinet doors on our Rover using climb cutting with a 5/8 diameter insert cutter router bit. We have a program written that cuts the ends first, removing 3 mm, then runs down the sides cleaning up the tear out.
Recently we tried to run some hard maple doors and the tearout at the entry corner was so bad that the clean up pass couldn't get rid of the tearout. Someone suggested that the climb cutting action was worse for trimming these ends and that we should run the other way for the rail ends. Any comments?
In my experience it doesn't seem to matter how you do it, it's going to tear out. There are a couple of things you can do--unfortunately, both are time consuming.
1.) On entry you can slow the feed rate down to .25 or .5 meters till you get the bit into the material, then ramp the speed back up. This will not work as well on exit. It will minimize tearout but not eliminate it.
2.) You can use a left hand bit on the entry portion and the exit portion of the other end. Go in about half way and then switch back to the right hand bit. I don't know if you have an electrospindle or a LH router but this will ensure no tearout.
Like I said though, these solutions are time consuming. One last option--this is difficult to pull off, but I did it one time on a bunch of interior doors: drop your saw right at the entry point and score the edge (3 or 4mm), then route. This will work. It's somewhat difficult to get the moon and the stars all aligned just right, so there will now be visible marks where you changed tools.
Brian Personett, forum technical advisor
However, I have also found that a .01" radius on the corners will eliminate tear out as well.