I have a trim router with a 1/4in shank size and need to flush trim plywood that is 30mm thick. All flush trim bits that I could find which are long enough are for 1/2in shank routers? What are my options and which one should I go with?

  1. I though about buying a 1/4in to 1/2in adapter, but I am worried that the adapter may be too wide. This is the 1/2 flush trim bit I set my eyes on: https://www.freudtools.com/products/44-108. As for an adapter, I would get something generic from Amazon.

  2. A shorter 1/4in flush trim bit and an extension, so the bearing can reach the reference surface to glide on. Once the first pass is done, I would move the flush trim bit up (now riding on the first pass' trimmed surface) and so on.

Any suggestions are welcome.

  • 1
    Hi, welcome to Woodworking. "...and which one should I go with?" ! You're an experienced SEer, you know that all Answers equally valid queries are specifically against the guidelines. You're also presenting two solutions and asking for respondents to pick from them, which is basically an X-Y problem.... Please re-frame the Q so that you put the problem front and centre, present the options you've come up with so far and ask for other solutions, rather than for people to pick between them (because that's a choice for you, and you alone, to make).
    – Graphus
    Commented Jun 3, 2023 at 8:05
  • Something like this: amazon.com/Nikou-Router-Bits-Straight-Woodworking/dp/B07PYNRBN4
    – gnicko
    Commented Jun 3, 2023 at 12:35
  • 2
    Option 2 will work in a pinch. A particularly long 1/4" bit might deflect if you push it hard. Option 3 is, "buy more routers". (Porter Cable 690 routers, for instance, come up on the local used boards very regularly, and are pretty bulletproof.) Commented Jun 3, 2023 at 13:59

1 Answer 1


Extensions and adapters,etc. are just going to get in your way I think. Get a bit with a longer cutting surface: enter image description here


This is an "almost random" example, not an endorsement or specific product recommendation.

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