Anyone have a horned nut for the underside of a trough-the-bench mount vise? It has 3/4-10 NC threads on the vise base.
If no nut available, is there a suggestion on how to make one?
Yes, you could make one which would look reasonably close to the original style, but, unless you are really 'determined' to have this part be 'correct', in terms of 'restoration', it may be too much work to be a practical project.
The obvious way to replicate the part would be to ask the someone here who owns a vise with that size/style of nut to make up a sketch of its dimensions.
With the dimensions known, you could readily carve a replica in any good dense hardwood, a suitable over size for shrink, to make a pattern for casting. Send the pattern to a specialist foundry which does small lot iron castings, such as the 'Cattail' works, and have several of the parts run (the others would likely be quite salable here, for other old style vise owners)
Improvising a fixture to hold the part for drilling/tapping 3/4-10, and facing a bit of a flat 'washer surface', or 'bearing surface' would be a simple, easy task using a Bridgeport class vertical mill .
Another option would be to replicate an 1870-ish vintage New England style, which would be to obtain a short length of, say, 1-1/2" square steel, drill/tap 3/4-10 at mid-length, then set the part up in a 4-jaw, and turn the ends round to a, say, 3/4" diameter, faired to the centre square section with a, say, 3/8" or so radius.
The 3/4 diameter should then be turned taper down to 5/8"-ish near the tips, and the tips finished with a 'ball' configuration. The part should then have the tips curled, heating only the tapered end to a full red, and bending gently/carefully to an aesthetically nice curve, taking care to bend the tips uniformly. The part should then be highly polished, the traditional so-called 'lime polish', heated to a 'straw, just beginning to get purple flecks' colour, oil-quenched, cleaned and varnished.
'Hmmm', you might say, 'either one of those techniques would require way too much working time to be a practical thing to do, just to restore an old vise'......well, I suppose you're right, considering that a hardened 3/4-10 heavy pattern nut is available 'off the shelf' as mill furniture, and might cost a dollar and a half, or so, and you already have an 1-1/4" wrench (or a 12" Crescent) ready to hand.
cheers
Carla