These work for #4 size longsprings and 4.5 sc longs.
Does anyone know if they make one very similar for #5 dukes and Bridgers?

I've never seen a bigger version. I have two that I use to set my 4.5s. if someone were to start building one that fits #5s, I'd definitely buy a couple.

Definitely!

Maybe we could talk someone like Tom Cat into building them.

I'm not gonna say that I can't. How do they work?

I can take pictures if you give me a minute.

Two designs that I'm aware of, one slips over the end of the spring, the other hooks from the side which is easier in my mind. When you pull the lever, the rounded end compresses the spring.

That's gonna a tough build. I've got coilspring trap setters that I need to get caught up on plus trapping season is on. But I'm not gonna rule this build out.... it's gonna take a while.

I've got 4 of them. 2 still in the package. Bought them at a friends sale.
Never really used them but I think my grandsons will.
just

Does anybody know what the square hole in the center was for? These could be laser cut if you have a metal shop that has one. Or a plasma table, but you would have to do clean up on the from the burned edge.

Not sure, but could it be for the old threaded jaw post type traps?

I'm thinking they be made with a hole saw and drill press. They almost looked punched out.

That was a great idea, I bet they work well and didn't take a lot to carry. would fit in a back pocket.

From handling a few of these, I would bet they were punched also.

A water jet would make quick work of them also.

I think the one sided setter could be made to fit multiple traps, by adding a 2nd plate alongside the side, with either drilled holes or a slot with a bolt to adjust to the depth of the spring...

The sliding part would have the base for under the spring....

If you make the round part more of an elipse you could get as much down pressure you need depending on the height of the spring.....

No idea of the purpose of the square hole, or why you would need it.

Square hole - maybe to unbolt a Newhouse trap after you caught your hand in it

I'll have to play with the setters when I get home, but I wonder if the hole is for sliding in a nail or stick when fully pressed, to lock it in place while you set the other spring.

See if that square hole fits the square nut on the jaw post on that trip in your pics.

I'll do that.

So do you use 2 of them at the same time on a DBL? Or is there a clip or something to keep one spring compressed while you do the other spring? I bet the wire EDM would knock em out quick. I wonder if a guy could scan a set and then scale it up in some cam software to use them on a bigger trap like a #5?