Tear-out on raised panel corners

Eliminating corner tear-out on raised panel cabinet doors when using CNC equipment. November 7, 2000

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

Run all panels as though they were on the shaper. Ends first, then sides. Don't climb cut. The shaper is still a lot faster for solid wood panels in my book, but we have been doing them on a Routech220. It takes too long to gasket each panel down and locate it for machining when the sizes vary.

Also try a sloping lead-in?

I had a lot of tear out on the corners of some work I was doing. To correct it, I overlapped the starting and ending points and this was done away from the corner. This eliminated corner tearout for me.

I have had good results using a drill. It requires you to compensate for the diameter of the drill. Drill a hole where the relative quadrant of the drill diameter is at the finished panel size end coordinate.

However, I have also found that a .01" radius on the corners will eliminate tear out as well.