Simple DIY Flap Sander





Introduction: Simple DIY Flap Sander

About: A husband & wife team. Amateur makers. Expert high fivers. New video every week (or so).

We’ve got a quick tip today - how to make a simple DIY flap sander. There are a lot of elaborate DIY flap sanders out there, but this is one you can make in a pinch. It’s great for getting into hard to reach spaces that are hard to get with a typical flap sander. Plus it’s super flexible: you can make it long and skinny, you can make the sandpaper itself longer or shorter, and you can swap out the grit whenever you need to.

Tools and materials needed:

Step 1: Clamp and Cut

First clamp down some ⅜” aluminum bar stock and cut off the length you need with a jigsaw using a metal blade. We cut off a length that was about 4”, but you could go longer if you needed to.

Step 2: Turn Into Split Mandrel

We’ll turn this piece of aluminum into a split mandrel to hold our sand paper. We placed it on our drill press V block to keep it centered (which we clamped into place), and cut a slit into it on our band saw.

Step 3: Insert Into Drill

Then pop the split mandrel into your drill and place a folded piece of sandpaper in the slit. Tighten the split end around the sandpaper with some pliers.

Step 4: Enjoy!

This is great for getting hard to reach spaces that a store-bought flap sander can’t get to, and it’s really so easy to make. Hope y’all found this helpful, let us know if you have any questions!

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    16 Discussions

    One end of the sandpaper strip has only its smooth side showing, so may I suggest a small improvement ?

    Cut the sandpaper strip in half, and glue the ends back to back to fit in the mandrel slot, then both sides will show grit to the workpiece. (Needs just a slightly wider slot.)

    4 replies

    They folded the sandpaper in half lengthwise so it has the business side of the sandpaper making contact all of the time. You can see it clearly at the 1:10 mark.

    Correction: it's actually the 36 second mark. I looked at the total time instead of the elapsed time.

    Thanks for the assist autotech1 :D and for the suggestion electrofrank!

    Ah yes. I should put my glasses on. And that makes it reversible as well.


    1 year ago

    You can do the same with 1/8" rod for a dremel. That gets into really small places.

    1 reply

    Yeah, great suggestion! I'll add that and die grinder to the suggested ways to do this :)

    NIFTY! The timing is just right for me. DI was agonizing on how to accomplish a tight corner and I've never heard of a "flap" sander before! Oooo who! Thanks!

    1 reply

    Yay, so glad we could help out :D Good luck with your project!!

    Thank you.

    Your youtube link is incorrect. It's set to the instagram one.

    1 reply

    AH, thanks so much for catching that!! All fixed now :)

    I find it either more satisfying or more efficient (perhaps less fussy than making numerous folds?) to glue partial sheets of sandpaper back to back. I let them dry completely, and with an old pair of shears long ago dedicated to sandpaper, cut several strips of the double-sided abrasive paper at one time. Mostly I've used spray adhesive, a light coat applied from a clean spray nozzle in the lower end of the adhesive's recommended temperature range for application, to keep the glue in a thin, even layer, as I want my abrasive faces to stay as parallel as possible for use in a couple of other custom sanding tools for metal fabrication.

    1 reply

    Neat, I'll try this out with some pieces we have to see how it works, thanks for the suggestion :)