I have made a router table fence with a "dust extraction" feature:

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As you can see there are gaps that would make the "box" not air tight. I need to use some kind of foam to fill those gaps.

The gaps are around 2-3 mm (5/64 - 1/8 inches) wide.

It doesn't need to be pretty, there isn't much mechanical stress, obviously it doesn't need to be food safe.

What solution/foam/etc would you recommend?

Later edit: Maybe even duct tape or something similar?

1 Answer 1


Caulk would work well. Anything will work - acrylic, painters, silicone, whatever you have on hand. You can caulk from the outside or from the inside of the enclosure.

Your suggestion for duct tape will also work, but will be more prone to deteriorating over time due to the dusty environment.

You can also make small wooden splinters to fit in the gaps and glue them. If done carefully it will even look (almost) seamless.

  • I agree this answer that caulking of some sort would be the best solution here, but wanted to add that for larger gaps you can also use window/door sealing spray foam (e.g. Great Stuff brand). Commented May 5, 2018 at 0:03
  • @SaSSafraS1232 you are correct - caulking will work well for smaller gaps (like the OP's), but won't work for larger gaps (at least without a foam filler strip). Expanding foam can work well for the large gaps, as you say
    – Eli Iser
    Commented May 5, 2018 at 2:10

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