Vintage "Jorgie" 4 inch "C" clamps

[burnsie]

Anyone know anything about these quick action Jorgensen "C" clamps? They're model 204.
I can't find anything on the internet on them and I'd like to see a patent drawing because something is slightly amiss with one of them. (The screw skews to the sid on one of them although it's not bent).  I'm thinking one of the springs on one of the levers is partially broken.

What decade do you think think they're from? The finish could be black Japan.  My WAG is the 1940's.

[Chillylulu]

Most probably the clamp is sprung. Someone overtightened it, pushing the frame out of alignment. When a clamp is mis-aligned, and the shaft is directed away from the center of the clamp, it is sprung 99% of the time.

A bent rod would be obvious. As it is turned the rod would swing around the centerline, instead of along the centerline.

Just because a clamp has a 4" throat doesn't mean you can clamp anything that will fit as tightly as you want to. Exceed the clamp's strength and it will spring.

I have seen a cheater used on the handle - it tightens up, but starts wearing the clamp out too.

Chilly

[JoeCB]

Clamps are malleable iron or forged steel, the sprung clamp can be bent back to shape. No heat required. Just muscle.   

Joe B

[burnsie]

Most probably the clamp is sprung. Someone overtightened it, pushing the frame out of alignment. When a clamp is mis-aligned, and the shaft is directed away from the center of the clamp, it is sprung 99% of the time.

A bent rod would be obvious. As it is turned the rod would swing around the centerline, instead of along the centerline.

Just because a clamp has a 4" throat doesn't mean you can clamp anything that will fit as tightly as you want to. Exceed the clamp's strength and it will spring.

I have seen a cheater used on the handle - it tightens up, but starts wearing the clamp out too.

Chilly

I don't think it's sprung because I can push the screw with my hand to make it vertical to the frame.  This is not your typical "C" clamp because they're are teeth on the levers which grab the threads. One side doesn't seem to grab the theads properly skewing the screw.

[Chillylulu]

That could be easier to repair if parts can be found.

Not to be a smart aleck, but, how do you think the parts were broke? My guess, without looking and definately a swag, is overtightening. It is the bain of clamps.

And, even if bent back they won't be as strong as the originals. They will bend easier in the future and the metal will be harder where bent than the surrounding metal. The work hardening can be re-annealed, hardened and tempered, but that is more effort than most are willing to expend on a clamp.

The truth is any reasonable pressure applied to metal, by pushing, hammering, knocking around in a tool box, tightening, etc. hardens metals somewhat. More obvious in lesser quality steel, unmeasureably slight in the best metals, and very obvious in most non-ferrous workable metals. (I am not sure how much it is in platinum group metals)

That is how you can break steel by bending it back and forth.

Chilly