Hello all! This has been by far the most helpful and knowledgeable source of help for me, so I turn to you in my time of need.
I’m making a vise (a “Moxon”) for woodworking. I’m using 3/4" 10 tpi threaded rod to drive the front jaw back and forth. But I need a comfortable way to turn the rod by hand and apply some torque (I don’t have numbers). I was thinking of making a crank arm out of 3/4" plywood maybe 8" long, drilling a 3/4" hole in one end, sticking the rod through and trapping the arm between four nuts and washers, two nuts on each side, tightened against each other and against the arm. But I’m not sure that arrangement will take the torque over time. I would prefer some kind of hardware that positively grabs the threaded rod and will not turn on the threads. I could grind the end of the threaded rod into a square or some other shape, or cut a cross slot in the end, but I don’t know what to do next. I could possibly drill a cross hole in the threaded rod, but that’s a little iffy for me, and again, what do I do next? Do I insert a steel rod to make a T and somehow attach the plywood arm to that?
Thanks in advance!
A few ideas in no particular order
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Find someone who can weld. Have them weld a coupling nut to either a flat flange of some kind (for you to bolt onto a wooden handle), or to a short section of pipe to make a sliding T-handle. You can then screw the coupling nut onto the end of your threaded rod. Or you could skip the nut altogether and weld the tube or flange straight onto the threaded rod.
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Buy a clamping knob threaded 3/4-10. McMaster-Carr carries them. If it isn’t big enough on its own it would be easy to make a wooden handle that would firmly engage with the lobes on the knob and couldn’t slip.
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If you use Acme threaded rod instead of normal all-thread you can get lever-style nuts which are designed to act like clamping handles. They are designed for making clamping fixtures, etc. McMaster-Carr
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Epoxy. Make a wood handle with a nice deep hole for the all-thread to fit into, I’m thinking at least two diameters so something like 1.5" or more in depth. Then just glue the all-thread in the hole with quality epoxy. So long as you clean the threaded rod first so there’s no oil or grime on it it should grip harder than you could ever hope to turn it by hand.
Thank you sir! That’s very helpful.
I think the epoxy idea would work for me. I think I’ll cut some lengthwise grooves in the threaded rod so the epoxy can key into it better, and maybe do something similar in the crank hole. And maybe add some coarse sand? Maybe that will reduce the depth required? What do you think?
I would like to buy Acme rod, but it sure is expensive, not the rod itself but all the other stuff, like nuts and flanges. I’m trying to keep this stuff cheap, both for myself and whoever else I give these ideas to.
Cutting some longitudinal grooves would be a good idea since it could key in better. It doesn’t have to be pretty. And it would be a good idea to rough up the hole in the wood as well, or maybe pick a drill bit that you know will leave a rough hole. This is a job where the crappy finish left by a spade bit or a hole saw is actually beneficial.
As far as adding stuff to epoxy goes: I’ve never personally used sand, but it is common to add various kinds of fillers to epoxy for different purposes. Things like sawdust, chopped structural fibers (fiberglass, carbon, kevlar), metal powders, and so on are common strength additives for epoxy. Other things are added not to add strength but to act as thickeners, like fumed silica or glass microbeads. So the idea of adding things to epoxy is nothing new, but I don’t know if sand would do much other than thicken? I don’t think it would hurt unless the sand was extremely coarse. The sand would help “cut” the epoxy so you don’t need so much, which would save money.
If you are going to use thickened epoxy then a good idea is to apply a little un-thickened epoxy to the wood first. Think of it like a “primer” that soaks into the wood better than the thickened epoxy does.
If I were going to do this I think I’d do something like:
-clean off end of threaded rod with solvent
-apply masking tape where you don’t want epoxy to catch any sqeeze-out
-mix a little epoxy in the bottom of a small cup
-use a popsicle stick or similar to paint some unthickened epoxy inside the hole
-mix thickener into the remaining epoxy
-butter it all over the end of the rod, making sure to fill up the threads and any grooves you cut
-apply a little thickened epoxy inside the hole too
-clamp & wipe off excess
Fantastic. Thanks so much!