Being nice to a vise

I made a simple Screw Jack by screwing a bolt into a Hexagonal Connector Nut (the sort that are used for joining two pieces of studding).

Obviously, the minimum space is the (length of nut + thickness of head of bolt) but it can be made as large as needed by using longer bolts.

I tidied it up by putting a taper on the top of the Connector and turned the top of the bolt round and knurled it (but mostly because I had made a knurling tool for my Taig Lathe and wanted to use it!).

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The jaws of one of my woodworking vice twist, but I find it useful for holding pieces don't have parallel sides. It is a vice that I rescued 50 odd years ago, refitting the metalwork into 2 old oak (really hard) blocks. It does seem to have got looser over the years.
I have never worried about about side loading my main engineering vice (a record 112) never seen it as an issue. But I have used packing on some of my smaller ones.
Interestingly, having read the start of the thread I also thought of using a thread connector bolt as the basis for a jack. Also I remember reading about someone who made replacement vice jaws that extended sidewards for bending metal.The end of one was tapped so that they could be pulled together - if I remember they were 18" long. It occurred that a small extension to the jaws would all a bolt in a tapped hole to hold them apart.