In an effort to improve the finish on my cuts I picked up a Hozly 1/8" two fluted down cut bit from Amazon. They came in today so I made a few sample 30 mm boxes to test them out on from a piece of poplar I had on the machine.
From left to right is using a piece of double sided tape, triangular tabs with a finishing pass, and square tabs with no finishing pass (the fastest).
- The double sided tape was a complete failure, it broke loose before the part was finished and left crud on the bit. It also put a gouge in the side when things came loose.
- The square tabs were a huge problem still causing shudders when the machine plunged. And you can't see it well in the picture but the surface finish is much rougher as well.
- Adding in a 0.5mm finishing pass and using 10x6 mm triangular tabs had the best effect, with a nice finish everywhere that would need minimal sanding. These bits were able to cut the triangular tabs with no noticeable shuddering, much better than the single fluted 1/8" upcut bit.
These bits need to be run faster, I ran them at 800 mm/min and 12000 rpm but I could probably have run it even faster (or slowed down the rpm's. It cut well but the chips were very thin, maybe a mm in width but the full height of the cut. It may be worth while to run these really fast and add in two finishing passes, at a slower speed so there is plenty of room if the bit wanders a bit on the fast moves.
Anyway they are an improvement over the single flute upcut bits I have been using, but not a huge one. I will probably keep these as my primary bit for now, but I would still recommend starting on the others. They are more forgiving, and the cost is so low you can break one a day without worry.
I'm not super eager to revisit double sided tape. It did not stick well enough and it was really a pain to put down, tending to bunch up at the cut line (probably part of the problem). Maybe the blue tape and crazy glue idea would work better. Anyway I would only consider using it for things like circuit boards that need to be very flat, and for much larger pieces where you can keep the tape far away from the cutter.
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