Some online shops selling CNC router bits only specify what metals the bit can be used on. Is it safe to assume that if the bit can be used to mill metals that it's safe to use all types of non-treated wood?

Specifically, I'd like to mill douglas fir, but also interested in walnut.

  • Can you even clamp those? The ones you get here have really small shafts, and above all else be sure not to try to clamp a too small shaft in your router, unless you are suicidal and/or want to spend money on buying new equipment. That aside, I would assume that they do of course cut wood, but I'd be inclined to believe that they probably have a different clearing optimized for the smaller "metal" shavings, and might thus clog more easily with the bigger and more sticky wood shavings. Either way, a bit which is guaranteed to work with wood costs you 20 currency, not a big deterrent, is it?
    – Damon
    Jan 1, 2016 at 11:51
  • Replacement collets are available to adapt most such machines to a reasonable range of shaft sizes.
    – keshlam
    Jan 1, 2016 at 15:18
  • I just removed the milling tag as i think it is not correct in the context of Woodworking SE. I started a meta discussion about it thou.
    – Stoppal
    Jun 21, 2016 at 6:37
  • Relevant to this dicussion: blog.inventables.com/2014/07/… (Including the gem: "However, on woods or laminates, that slight upward pull can cause a some chipping of the grain around the top edge of the cut as the grain is pulled upward instead of shaving cleanly off. A straight flute bit pulls material neither up nor down, and so behaves well on wood." I don't know enough about milling to make this into an answer.)
    – user5572
    Nov 7, 2018 at 16:30

4 Answers 4


I can't imagine a bit capable of milling metal having any difficulty whatsoever dealing with fir or walnut.

However I don't know you can assume that a metal-cutting bit will leave a particularly good surface on wood because of the different edge geometry (similar to twist drills, where metal-specific ones are subtly different to general-purpose or wood-specific ones). So it's probably a good idea to expect that a very light skimming cut will be needed to finish off.

  • maybe some routing bits for metal could get (over)loaded with shaved wood? Mar 29, 2018 at 14:45
  • @AndreiRînea Yes, quite possible.
    – Graphus
    Apr 1, 2018 at 14:45

I agree with Graphus, however also be careful of the max. RPM of the tools, since metal-cutting tools are often designed to run more slowly than woodworking tools.


Our engineers sometimes do this, usually testing the stability of the spindle and the fuselage, but not too long, and the original drill bit can be used for very thin aluminum panels. For environments where the voltage is not stable enough, the use of metal-specific drill bits is very dangerous. The coil of the motor controls the power, and the difference is still very large. If you don't use it often, you can buy a voltage stabilizer (not a voltage regulator), or you can use it occasionally.


Milling cutters can be used to cut wood.

Milling cutters and router bits have different geometry that recognizes much higher SFM used for wood and plastic. A milling cutter can, of course, be run at high SFM in wood.

One thing to be cautious of is chip removal. If you are edge milling it is not an issue, but if you milling a pocket then you could get sawdust buildup in the pocket that could jam or overheat the cutter.

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