Surfacing Hardwood - Upcut or Downcut Endmill?

Let’s say you have a block of splintery hardwood that is already cut to final length & width and you just want to clean up the surface by taking off maybe .01" or .02". Here’s the toolpath:

The top corners need to be perfect - no chipping/splintering as the bit makes the final pass around the top edge. What would you use for the best chance of success - 1/4" Upcut or 1/4" Downcut?

I may be wrong here because I’m fairly new still but with such a shallow cut I would say down cut leaving the cleanest finish along the wood. I would also say if your CAD supports it to use a raster tool path so that you go with the wood grain


Yep, cut along the grain if you can.

Also, consider clamping some sacrificial pieces around the sides so the tearout happens to those instead.


I would also make the surfacing toolpath oversize, such that it starts outside the material, and with a stepover chosen such that the first pass that actually starts at the corner and edge, does so with a low radial engagement


Is it not an option to use a card scraper or scraping plane?

I would draw the toolpath so as to follow the grain, something like:

and surround the block w/ sacrificial material to minimize the chance of blowout if I had to do it on the machine.


Since you’ve already performed the finished dimensions, I would probably start this way.

No cross grain cutting unless its a clearing cut intended to be followed with a very light with grain cut.

I’ve fallen in love with my downcut bits. I would use one to do a thin (1/2 bit diameter) periphery cut that starts away from a corner and moves towards the corner in four separate toolpaths. Go slow.

As others have said, use a sacrificial edge to help support those corners. The edging could be part of your clamps.


It’s still on the machine as there are additional operations to perform. I like your “with the grain” toolpath. What’s your vote, Will? Upcut or downcut?

Downcut — meant to specify that.

downcut… and I’d do a stepover of no more than 40% of the diameter, and also oversize the cut by half a diameter to avoid leaving little “towers” in the corners and to make sure the edges are super clean
(if you go EXACTLY to the edge you might get some fuzzies left, and if you did not place the block exactly square you also have no margin for error)

if you have the Pro license for carbide create I’d also use the engraving toolpath instead of the pocket toolpath, oversize by a diameter and a half in all directions and then set the angle to be aligned to your wood grain. (or if your machine is a bit more square in one direction than the other, optimize for that)


This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.