best bit(s) and technique for pockets in hardwood?

[bking1836]

Hello,

I'm just a few weeks into my first ShopBot and having a ball. I'm definitely a newbie.

I've cut a bunch of plywood with the Whiteside compression bit, which works like a dream. Jumped into the hardwood world with hard maple today.

For pockets I used the Onsrud 1/4" downcut that is part of the ShopBot starter bit set. Offset, climb, with a 2" ramp in. The top edges were very clean as you'd hope. The bottoms and sides not so much, with obvious tool marks. And because the pockets are small, it's a royal pain to try to sand it out.

Would a raster cut be better, as it would track the grain better?

Would a very shallow .02 last pass make a difference?

Or should I run a first pass with the downcut for the pockets (and the profile cutouts while I am at it), then follow up with an upcut for the rest?

Thanks!

30936

[Brady Watson]

Or should I run a first pass with the downcut for the pockets (and the profile cutouts while I am at it), then follow up with an upcut for the rest?

Try it...Definitely better than a compression. I believe Onsrud and others also make geometries for clean bottom surfaces.

-B

[srwtlc]

Try raster with profile first and leave an allowance on sides and bottom of about 0.015"+ and then run a final pass with slower feed and a bit higher rpm. I cut a lot of hardwoods with 1/4 and 3/8 comps and can get an edge that requires little to no sanding as long as the bit are in good shape. Oak and walnut yield the best results and hard maple can be more difficult. If you do raster with profile last, the tool can/will deflect at each end of the raster cut (when clearing the pocket) and leave marks that go beyond the profile.

FEM comps and FEM downcuts work well for cleaning bottoms.

[barrowj]

Scott,

What is a FEM bit? I have never heard that term before and have searched and only found one link and that was to a Centurion bit.

[srwtlc]

That's where I get them. As far as I know, it stands for finish end mill (or possibly full end mill). They have a cutting edge ground on the bottom that shears the wood as opposed to a normal end mill where the cutting edge along the flute ends at the outer tip of the flute and that tip or point can leave more swirl marks in pocket bottoms than the FEM version. For the best pocket bottoms, look at some of the bowl and tray bits. For those, beware of cheap ones, as they can have poor grind angles that can leave a slight V path. Jesada, Infinity, and CMT have been the best for those.