I have been having trouble with resurfacing a bowed piece of plywood using cheap amazon bits 1.25 inch and 2 inch both with awful results. I understand they are cheap but anytips. The wood is 3/4 plywood . Any tip comments or input? On of the bits was smoking 1inch running at 75ipm and approx 15000 rpm depth .1.
My cheap Amazon bit was doing that. I bought a diamond card to sharpen my bit. Made it last a while longer till I purchased another.
Only take .003 - .005 cuts so I run at 125 ipm 10k.
Thanks! Ok wow only that much ill try it a my dewalts slowest is 16000. How fast is to fast of a feed rate?
You will have to experiment or use a chip calculator. The key to resurfacing a board is a small depth of cut and a fast IPM. The 1" or larger fly bits generate a lot of heat. The Makita/C3d and Dewalt routers are only 1-1.25 HP and the large bits are hard on them. So as @Zman indicated take light cuts and a fast IPM.
Put squiggly pencil lines all over the surface of the board and when they all disappear you have a flat surface. Just remember that the bottom is also bowed and while you can clamp it flat in the end when the clamps are removed it will still be bowed unless you surface both sides.
Trying to straighten out plywood may work but it will be ugly. The plys will show through depending on how much you have to take off. So in the end you may have to take off more than you think to get a descent looking surface. You may cut completely some plys and only part way through others if the bow is pronounced. Even if you paint the surface the grain from the underlying plys will show through because every other layer is 90 degrees to the previous layers.
I was pocketing out some baltic birch the other day and one layer was a very dark brown. Plus a lot of plywood has voids in the inside plys and will appear as you cut the layers down.
Good Luck but maybe pick another material.
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I can’t think of a good reason to resurface plywood. If it’s bowed from warp, you will get random thicknesses. If it’s bowed from delamination, it’s not worth using. There is a trick you can try:
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Burning == friction. To reduce friction, lower RPMs, increase feedrate so you don’t spend as much time in one place.
For my 1" bit, I run 10K RPMs, usually start at 150 ipm and use feedrate override to increase speed to 200 ipm or more.
For a larger bit, you want even lower RPM, but that’s not possible with the router / spindles these machine use. Increase your feedrate, and take shallow cuts. Once you can cut without burning, you can try increasing your DOC until things aren’t happy.
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