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Solid wood bits5/25
We've finally gotten comfortable enough with our nesting machine that we are making jigs and machining solid wood parts with it quite a bit now. I've been using a low helix roughing D/S bit followed by a low helix U/S finishing bit. It gives a great finish as long as I'm going with the grain. However, even when I change from conv. to climb in the right places, I'm stil getting a bit of tear out. So, I'd like to have 2 permanent tools set up for that in the holder - 1 LH and one RH and skip any finishing bit.
Typically, I run a 3/4" 3 flute Upshear with 30° helix. Try Vortex 1880. Three flutes give me a better finish. To eliminate tear out, cut the end grain first, then the direction of the grain. That should remove the tear out. I only use left hand tools when I have to do a notch or cut out opposite the grain direction. Climb cut the grain direction. You can get away with conventional on the endgrain, but I just climb cut everything. In most species, cutting around closed geometry will result in tear out at the corners. Vortex also has Pass by bits in the same series that allow you to cut up to 4-1/2" thick solids. We use those quite often too.
We have had the most success with a 3 flute slow helix 3/4 or 1/2" Dia bit. The slow spiral does not tear the material as bad. Plus you still get the benefits from the 3 flutes for finish.
We cut all our solid wood parts with either a 2 flute 3/8" upcut or down cut spiral bit.
We typically run the parts in 3 passes.....2 climb and 1 conventional.
The reason for this is that we hold the parts on pods that don't do a 100% solid job of locking the parts from slight side movement while being cut. During the first climb pass the parts typically side shift away from the bit .015" to .02". This leaves the parts slightly oversized. The 2nd climb cut pass brings them down to size as the bit removes the small amount of remaining material. The conventional pass then cleans the edges while just kissing them.
Doing it this way we get virtually no tear out at the corners and clean surfaces on both running and butt grain.
You might think this is too much time spent cutting a part. However the difference is really just a matter of 30 seconds or so on a curved moulding that is going through several hours of processing start to finish.
I have one operation where we use a 3/8" compression bit to finish the edge of solid wood parts that need to be crisp edges on top and bottom. Other than that we use standard up or down spirals. Sometimes we use a roughing spiral for hogging operations.
I am not sure if that is industry standard or not. We have had success cutting with those tools for over a dozen years cutting all species of hardwoods. We try not to mess with what works. No issues with Chipping either with the grain, or end. I am usually cutting using a pressure fixture that I build from scrap melamine and gasket that I buy from All Star Adhesive. Those parts aren't going anywhere. If it is just a quickie, one off, we might tape with 2 sided tape right to the spoilboard.