Fixing a Slipping F-clamp

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About: I'm a elektromechanic, who likes to create, build, repair various items, tools, etc. And I tought, why not share some of my projects with the rest of the world.

Over time, and a lot of use, most F-clamps start to slip while tightening. If you use cheap clamps, as I did, you can have the same problem.

In this instructable you can read/see what you can do to fix the slipping.

Step 1: What You Need

All you need is a triangular file.

If you have a bench vise it is the most easy way to work. If you don't have one, you can tighten the F-clamp to a solid piece of wood or metal, so that the clamp is horizontal.

Step 2: Start Filing

Put the F-clamp in the vise and start filing. Just deepen the grooves in the clamp. I did 3 strokes in each groove.

As soon as you've finished the outer side of the clamp, just turn over the clamp and do the inside as well. You will notice your clamp has more grip after this filing.

All needed to get some more life out of your F-clamp was 5 minutes of filing, no extra cost.

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    10 Discussions

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    perec3

    3 months ago

    Great tip! Thanks!

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    ElectroFrank

    3 months ago

    I have also successfully used this technique with a hacksaw, junior or senior according to the size of the clamp. A saw blade enables finer grooves, as the angle of a triangular file may be too blunt to cut finely enough.

    2 replies
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    PFOElectroFrank

    Reply 3 months ago

    I thought about using a hacksaw too. But I was thinking the opposite of what you're thinking. I thought by using a triangular file I would create sharp edges, so the clamping part would grab easier. With a hacksaw you don't really have a sharp edge. Bu the more I think about it, the more I think both methods would yield comparable results.

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    ElectroFrankPFO

    Reply 3 months ago

    Ah yes, I should have said, use the hacksaw blade at a 45 degree angle to get the sharp teeth you want. Only a very shallow cut is necessary to provide grip, as (I think normally) the moving jaw part is made of a softer alloy than the steel bar, so that the teeth can bite into it.

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    throbscottle

    3 months ago

    Wow, I have this exact clamp! Possibly the only decent tool ever made by Blackspur. Came from the £1 shop years ago, still going strong!

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    bpark1000

    Tip 3 months ago

    If the clamp is slipping, you need to look at the pins that bear on the beam first. These get worn every time the clamp is slid or tightened. (The force is concentrated in 1 spot on each pin, whereas the wear on the beam is distributed, unless you always clamp the same thickness stock at the same screw setting.) When they wear, the sliding member becomes more inclined, giving less normal force. I would inspect those first. Look for flats on the side that faces the beam. Replace or rotate them to a fresh side of they are worn.

    Another strategy is to let the clamp rust on purpose (if the beam and pins are not plated).

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    GTO3x2

    3 months ago

    Good name for these.

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    JohnC430

    3 months ago

    thanks for sharing. nice idea.

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    Yonatan24

    4 months ago

    I've also had success using a hacksaw on a really old clamp. But my new bar clamps have bigger grooves and a triangular file might do the trick since they are starting to slip. Thanks for the idea!

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    Alex in NZ

    4 months ago

    I have even cheaper F-cramps where there are no grooves at all on the back edge of the spine. Yet. Thank you very much for the inspiration to go and fix that. :-)