Bit Selection for MDF

I’ve done a bunch of research on tooling recommendations for cutting MDF. Of course, it’s hard to find a straight answer, so I thought I would reach out to this group and see what people use. Any feedback would be greatly appreciated.

Here is what I was looking at purchasing:

  • 46170-K CNC Solid Carbide Spektra™ Extreme Tool Life Coated Compression Spiral 1/4 Dia x 7/8 x 1/4 Inch Shank (Roughing Pass)
  • 46176-K CNC Solid Carbide Spektra™ Extreme Tool Life Coated Compression Spiral 1/8 Dia x 13/16 x 1/4 Inch Shank (Finish Pass)

You won’t get a consensus. Compression bits are nice for edge cutting because if used correctly with the transition between up-cut & down-cut somewhere in the middle of the stock, the material won’t fray as much on both sides. Slotting should be done primarily with the up-cut portion. And pocketing should be done with a rough pass (or passes) then a finish pass that is deeper than the up-cut portion of the bit.

So it really depends on the projects you want to make & how you plan on cutting the MDF.

They’re expensive bits. If you only use the end of the bit, no point spending the extra money.

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I’ve done well w/ our #251 down-cutting endmill in MDF:

just need to make sure chips are being evacuated and not packed into the cut and re-cut.


Thank you! With the high price point, I wanted to get some confirmation before pulling the trigger. I’m cutting out a bunch of gears from 5/8" stock. I’m still new to CNC work, and this will be my first time cutting MDF. Sounds like I’m on the right track.

Do you have a particular brand that you recommend? I’ve only used the Amana bits so far.

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