Just thought I’d share the astronomical difference between upcut and Downcut bits on plywood.
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Very interesting. Though, I don’t know which is which.
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I’m guessing upcut is on the top and downcut is on the bottom. Did you get any sled lifting with the downcut?
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Yes you are correct, upcut on the top (may have been a little dull too) and down cut on the bottom… I never thought about the lifting un till you mention that… It did lift a little near the edge on the bottom left of the workpiece but I think it was from lack of support height around the work peice because I was cutting so close to the edge… you can see that octagon angle isn’t quite as sharp near the “V” ion Valley… (5ml step down, 12ml thick workpiece)
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which is why its a good idea to make at least one tool change when cutting. perform all of your cuts first witth a down cut bit then change to an up cut but to finish to full depth. this will prevent tear out on the back side and hep evacuate chips from the kerf.
EDIT:
Just to add that its more work because you have to create more tool paths and set up a tool change but for me it was always worth it. I treated the first downcut pass as a “scoring cut” and it was almost always a .125” depth. Then I would change to an upcut bit and finish the rest of my cuts with that.
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