Smooth Plywood Cuts with CNC Equipment

Advice on preventing "fuzz" when cutting out plywood parts. October 26, 2005

I am cutting bird mobiles out of .25 - 5 ply birch plywood, using a .125 down shear at 10,000 rpm, 100in/min. It was previously done on a scroll saw. We want to do it on the CNC for speed, so we want to eliminate sanding. The result is fuzzing at the different layers. How can I get rid of this?

Forum Responses
(CNC Forum)
10,000 rpm's is way too slow to run a .125" cutter. Spin that thing as fast as your spindle will go (probably 18,000 rpm's). This may or may not solve your fuzzies, but it will make your tool last a lot longer.

You might want to try a different species of plywood core. Maybe poplar core, or apple ply. The Baltic birch is difficult to cut without fuzzing.

Is the edge of the off cut a nice finish? If so, cut in the other direction.

How large are the parts you are cutting? If you can get enough VSA (vacuum surface area), you should be able to cut the parts without tabs or secondary sanding.

You should be cutting at 18,000 rpms and climb cutting. With that small of a diameter and with a down shear, the chips are not going to evacuate, thus they are being recut. If you can't use an upshear, try a straight flute solid carbide.

We cut 12 mil and 15 mil Baltic at 500 inches/minute using a 3/8" down spiral (57-325 Onsrud Cutter) at 18000 rpms, and the edges are smooth, with no fuzz. This may be pointing out the obvious, but this kind of bit only cuts well on one side. In our case, the inside, going in a counterclockwise motion. Make a full circle around the part, or go to a point and come right back to where you started to make it smooth on both sides of the cut.