How do you make a pocket really precise, hard and smooth in MDF (and don't say sand it)

If you’re seeing that much variation, something is probably mechanically wrong w/ the machine — check the pulley set screws, belt tension, Delrin V wheels — per the machine operating checklist: Machine operating checklist , the basic points of adjustment for a machine are:

Yes, RPM matters — you should use feeds (selected in Carbide Create) and speeds (applied by the dial setting on the compact trim router used when cutting) — this could also be an issue. Extensive discussion at:


One thing I like to do is to adjust the Depth per Pass in Carbide Create so that the final cut of a pocket is a very light cut — say that one wants a 1/2" deep pocket (0.5") and the depth per pass is specified as 1/8" (0.125") — the machine will make 4 passes:

0.5 / 0.125 == 4

If you reduce the depth per pass for that pocket to 0.12", you will instead get 4 full-depth passes, and a finishing pass of 0.02".

To get the same effect around the interior you would inset this pocket to leave a roughing clearance, then only cut to 0.48" deep, then assign a second pocket operation which you cut 0.5" deep in a single pass using the original geometry.

If a Probe operation is off, how it is handled depends on when it is determined:

  • if before the cut is begun, re-probe, or manually adjust the zero
  • if during a cut, pause, stop, re-initialize, and begin again