Choosing and using bits

My maslow is coming soon. I need to order some bits. Not sure the best ones as I see some projects with alot of tear out and others that are just a clean cut.
Is that because of the bit or because of speed at which the design is cut?
Also are there different bits some vets have known to work better with different qualities of plywood?

Upcut bits can cause tear out issues on the top of the wood.
Downcut bits can cause tear out issues on the bottom of the wood (and can cause fires if you attempt to drill holes with them or use them without a vacuum attached)
Compression bits try to be the best of both worlds, reducing tear out on both the top and bottom of the board. They work best on plywood and laminate, not solid wood.

compression bits only work if you are cutting the full depth of the wood in one

straight single-flute bits work well and are a lot quieter than the spiral bits
sold by maslow

This is not true for plywood. Compression bits work fine in plywood, provided the first pass is at least the depth of the start of the compression flute (on the maslow bits, i think this is .15 in) into the material.

> Thanks to modern end mill and router bit design, you can now have your cake and eat it, too. Compression bits do both upcuts and downcuts at the same time. They have flutes that upcut on the bottom .250″ or so, and flutes for rest of the cutting length that are for downcutting. These are the cutting tool of choice for laminated materials such plywood. But you have to use them correctly. Your first pass needs to be slightly deeper than the upcut section of the bit, say .260″, then the remaining cutting area on the bit will push down the board and cleanly cut that top surface without tearing the thin top veneer layer. Also, if you cut all the way through the board, you get a bonus: The top cutters don’t tear out the bottom veneer layers because they are pulling the fibers inward. A win/win situation.

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Some plywood is better than others. I’ve cut a lot of luaun underlayment because it’s cheap (cut several sheets into blanks when I got my first CNC router, still have a drawer full) and it’s prone to chipping. Experiment with first pass DOC and feed rate if you want to learn more.

Luaun looks nice with a bit of sanding and a clear finish…

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