What's my line. / What is this tool / item used for-- panel had to guess.

No, it’s not for splitting or cutting. That bit is sharp but it’s not needed for its function.

Does the “pin” move forward when you turn the knurled bit at the end, what happens if you turn the knurled bit in between the handles?

DavecUK

The pin is fixed to the leg. The centre knurled bit rotates but that is not important, the centre bit is spring loaded and moves back and forth.

Elcarajillo

Near enough. It’s a pair of lockwire pliers. Used for twisting stainless wire to lock fasteners in place. Often used in racing where regulations stipulate the sump plugs etc have to be wired to stop them unfastening to prevent oil being dumped on the track, but also useful for stopping bits of classic bikes vibrating off. Made by Loctite.

Elcarajillo Yup - it’s a wire twister. You grip the wire in the jaws which lock shut, then pull back the large knurled knob that spins the tool and the wires.

Norvin, you were too quick for me. :-)

Is it some kind of sine calculator, or some other compound angle plotter or calculator? Where do you get all this weird stuff! :-)

An adjustable template for marking out… something.

Pantograph device for scaling drawings?

Is it for working out unusual mitre joints?

I have never seen anything like it….do you actually have any ordinary tools in your workshop?