I am looking for a router bit that I don't know if it exists and if it does what it would be called so that I can find it.

Basically what I want is a flush trim bit but one where the size of the cut is of a smaller diameter than the bearing wheel.

What I am looking to do is use a pattern made of steel to cut into wood, and I need to be sure the bit won't ever reach the pattern in case I am off by a tiny bit and destroy the pattern and/or the bit.

Does such a bit exist, and if so, what would it be called?

  • This is typically achieved with interchangeable bearings of different sizes. You can also wrap tape around the bearing to make it larger. But if you have height set incorrectly, or you tilt the router, you can still jam the bit into the pattern. If you make the template very much different in size than the result in the right way, you can use a collar on the router base rather than a bearing.
    – Ecnerwal
    Commented Jun 2, 2021 at 2:08
  • Yes, they exist. Try searching for "offset flush trim router bit".
    – Mark
    Commented Jun 2, 2021 at 4:10
  • Yes the bit exists but product recommendations are off topic,
    – Ed Beal
    Commented Jun 2, 2021 at 4:59
  • Another technique is to use a regular, non-bearing straight bit, and pattern guide bushings. Commented Jun 2, 2021 at 6:02
  • @Mark -- "offset flush trim bit" is probably the answer I was looking for, but the other two might also work for my uses from Ecnerwal and whatsisname. If one of you wants to add an answer, I will mark it. Commented Jun 5, 2021 at 3:43

1 Answer 1


"Offset flush trim bit" from @Mark is the answer to the question I was asking. The comments to the question also offer other helpful advice.

  • 1
    If you end up with a very custom need, there's always the option of having one made by a custom tooling maker. Machinists do this for shaped tools with some frequency, but there's no reason you can't do the same thing for wood bits. You might even be able to take one that has a bearing you like, and send it in for modification. Or learn how to grind your own on a bench grinder with a steady hand :-)
    – Jon Watte
    Commented Jun 20, 2021 at 3:14
  • 1
    @JonWatte -- that's not a bad thought. For my purposes I could see doing that as long as I could incorporate some added safety to the process (metal pattern, wood stock). Commented Jun 23, 2021 at 23:43
  • 1
    @JonWatte custom router bits are used a lot for restoration work where the original pattern can't be accurately duplicated using off-the-shelf bits. I looked at having a set made for some window sash work but the cost was..... a lot of money.
    – Z4-tier
    Commented Jul 19, 2021 at 23:23
  • I know what you mean. When the cost of even a reasonably powerful router motor is a few hundred dollars, paying just as much for a single custom bit, stings! You could get blanks and a bench grinder and make your own, though ... If you have infinite patience :-)
    – Jon Watte
    Commented Jul 20, 2021 at 3:41

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