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How Can I Fix Bar Clamps that are Slipping?

⁽ᴿᵉᵖᵒˢᵗᶦᶰᵍ ᵗʰᶦˢ ʰᵉʳᵉ, ˢᶦᶰᶜᵉ ᴵ ᵍᵒᵗ ᶰᵒ ʳᵉᵖᶫᶦᵉˢ ᶦᶰ ᵗʰᵉ ᴬᶰˢʷᵉʳˢ ˢᵉᶜᵗᶦᵒᶰ⋅⋅⋅⁾

I just found an antique bar clamp (An ELZETT, a bit smaller than that one though). I've removed most of the rust, but:

The sliding jaw doesn't lock onto the bar when I tighten the clamp. It looks like The notches were very shallow/small, to begin with, and they've worn out quite a bit. I tried enlarging the grooves/notches that were on the bar with a hacksaw, but that didn't really help.
Does anyone have an idea for making it lock/catch on the bar? My grandpa might have several more of these clamps, and I don't want them to go to waste!
  • Drilling holes into the bar and adding a removable pin - no, because this steel is really hard and I'd go through 10 drill bits!
  • How about building some type of wooden cage around it that will hold it in place?
  • The only thing I can think of is to take it apart, and use the hardware for a homemade wooden clamp. But I think it would be easier to start from scratch...

I really want to fix this clamp! The quality of old tools, throat depth of this clamp, the screw, the swiveling pad - I need these!

Thanks!

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Yonatan24 (author) 1 month ago

Hmmm... How about cheap diamond holesaws from eBay?

I wonder if they can drill through steel. If I do try this, I guess I'll have to think of the size: not too weak, but so I'm not weakening the bar!

Yonatan24 (author)  Yonatan241 month ago

And I wonder how long they can last.

I had that slipping problem with an extra large but also extra cheap clamp.
Before you start messing with it please confirm:
A) The notches on the bar are still present and not "flattened" - meaning the small cuts are not pressed together.
B) The movable part of the clamp has not too much play!

The A bit is usually not too important as the notches only offer additional resistance.
If in doubt a slight cleaning with a sawblade will fix worn bits and you don't have to go deep - just very straight.
Part B is where things get interesting as it needs to sit on the bar at very close to a 90° angle.
If this part becomes "droopy" there won't be enough friction to hold it in place.
Also, once tightened on an object the angle becomes even worse.

If you want to find a suitable fix for yours start like this:
Add a thin metal strip (or plastic if nothing else at hand) in the hole for the bar.
Do this on the oppsite side of where the notches would grab - the smooth side.
In case limiting the movement like this already solved your problem you have to figure out how to make it permanent.
I was lucky as my cheap one was not make from cast iron but "real" steel.
So I folded a thin steel strip to a U form and placed it into the slot, then welded it place with two spots.
However this was not permanent as the little play between strip and wall of the slot was enough to break the welds after a few weeks.
I was able to make it work far better by tapping a thread into the clamp to take a grub screw.
The screw was adjusted so the clamp had very little play and fixed with a drop of thread locking glue.

Yonatan24 (author)  Downunder35m1 month ago

This definitely doesn't look to me like a cheap clamp.

It looks to me like they've mostly been worn out. It does have quite a bit of play, but I think it's OK.

I've been trying to use the clamp, and I feel that it's getting better. If it doesn't work, I'll try drilling holes with a diamond holesaw for a removeable key, or whatever those are called.

Yonatan24 (author) 1 month ago

Hmmm... It's working better than it was before.

Maybe somehow with toggle clamps?