Re: Twin Screw Vise
William Duffield, on the Cohansey
>I made levelers from half inch NC threaded rod, threaded connectors and a few nuts and washers when I built my bench, several years ago.
Three issues:
First, I think mine are plenty stong enough for a very heavy bench that gets very heavy use, even without the custom made plates. I've never had a failure. The threaded connectors are buried up in the legs, and are supported on a fender washer also buried in the leg. There is three inches of half inch diameter hole in the leg below the bottom of the threaded connector, which provides all the lateral support the bench needs. This hole also extends a few inches above the connector and washer, to allow room for the top of the levelers when fully retracted. I glue up my leg posts, which allowed me to easily cut all the holes for the leveler hardware. Cutting the two halves of the slot for the fender washer was about the best use I've found yet for a biscuit jointer :^)
I have a concrete floor, and find that pads made from hardwood plywood provide enough sliding friction that the bench will not move unless I decide to move it (as described below). To make the pads, I glued two pieces of 3/4" x 4" x 4" plywood together face to face, drilled a hole through the center to accept the end of the threaded rod and a nut, and then drilled a larger hole about a half inch deep to accept a washer that carries the weight of the bench. I bolted the washer between two nuts. All the hardware I used was available for a few bucks at the Borg. If you want to be structurally overinsured, and want to use 3/4" threaded rod and connectors, you can get what your need at McMaster-Carr.
To move the bench, I roll a couple of furniture dollies underneath, and put blocks between them and the trestles. Then, with an open end wrench, I raise the leg levelers, using the upper support nut, that sticks out the top of the pad, until the weight is resting on the dollies. I move it wherever I want it, and then crank the levelers back down, lifting it off the dollies.