[Thomas91]

Good day! I recently purchased a corn type bit set.
https://www.amazon.com/dp/B07TRFWXL8..._87e2FbJMS6844
How to choose the right feed rates for corn? I read everywhere about the speeds of standard spiral bits but did not find about corn. I think that corn has different speeds than regular spiral bits. And there is no corn bit option in all calculators and apps. How to find the right speeds? I wanna mill the plywood

[awerby]

I've never heard them called "corn bits" before; did whomever sold them to you refer to them that way? Normally they're called "diamond-cut" or "diamond-pattern" end mills. If you search under that name, you might have better luck. (Here's a chart: https://www.precisebits.com/referenc...tfeedspeed.htm ) But usually they're used for cutting composites, not plywood. I doubt they have enough chip-removal ability to work very well on plywood, unless you're just using them for a finish cut.

[Thomas91]

Oh, thank you very much! You helped me a lot!) What bits are best for cutting plywood?

[awerby]

Compression bits are designed for plywood cutting; they have downward flutes on top and upward flutes toward the end. That keeps them from pulling the veneer off the surfaces. But they often have difficulty in clearing the chips. Even a regular straight router bit would do a better job than those diamond-cut bits. Make sure it's a center-cutting bit if you haven't got pre-drilled holes for entry.

[Thomas91]

Yes, i know about compression bits, but they are minimum size is 3.175 mm, smaller i can't find. This is the only negative. I just need to cut the locomotive parts out of plywood, unfortunately I don't have a laser engraver. The smaller the diameter of the bit, then I will be able to determine the scale and more precisely I will be able to make a cut. Regarding compression mills, what feed rate and spindle speed would you recommend for a 3.175mm cut diameter?

[Thomas91]

I bought these mills: https://www.amazon.com/dp/B073RKCWGH...ing=UTF8&psc=1
I didn’t understand the moment with cutting into the material. Are these mills bad at drilling vertically? Will a smooth plunge cut save the situation?