Sliding Vise Bushing and Mortise for Nut
2010.01.14
Bushing for Vise Screw
The vise screws from Big Wood Vise are 2″ diameter. I drilled the through holes at 2–1/8″ so the screw would not rub. To provide some support though, especially with the vise fully extended, I designed a bushing. Some months ago I ordered a small sheet of 1/4″ black polyoxymethylene, commonly known by the trade name Delrin. Delrin has a low coefficient of friction, which I thought would work well for this purpose.
I spent quite a while today making the round Delrin bushing. But I was unhappy with the result. I used a 2″ hole saw bit in a corded drill to make the hole for the vise screw. The sides were pretty rough and uneven. If I’d had a drill press, maybe this would have worked better. With such rough side walls, what was the point of using low-friction Delrin? I had intended to use the Delrin for the garters on the show side of the vise chops as well, which also will rub against the vise screw. The Delrin does not look as nice as I thought it would. Although the surface is dead flat, visually it looks like globs of plastic that have hardened, combined with fine parallel lines.
So I abandoned the Delrin and decided to make the bushing out of some 1/4″ oak.
I switched to a sawtooth forstner bit, and drilled a through hole in a scrap of plywood to use as a guide. I sandwiched the 1/4″ oak between the guide plywood and another scrap piece below. The resulting hole was pretty smooth. Better than the Delrin at any rate.
I cut the 3–1/2″ outer diameter with the jigsaw, and tweaked a few spots with a cabinet file. Then I predrilled and countersunk four holes for screws.
So now I had an oak copy of the Delrin bushing. I secured it to the sliding vise base with 3/4″ 10–24 flat head socket cap screws from McMaster-Carr.
Mortise for Vise Screw Nut
Next I had to make a mortise for the vise screw nut. First I cut the nut block down so it would fit between the 3/8″ bolts on the sliding vise base. Then I threaded the screw through, and clamped the nut. I traced around it with a pencil to mark where the mortise will go.
With the outline marked, I removed the rear guide piece and cut out the mortise with the jigsaw. I tweaked it with rasps and cabinet file until the nut fit.
To drill the holes for screws all the way through the nut into the sliding vise base, I had to get an extra long drill bit. I used a piece of tape to show me how deep to drill. Once the holes were drilled through, I removed the nut so I could get in there with a tap to make threads in the wood. Then I put the nut back in place and tightened the screws. I used 4″ 1/4–20 socket head cap screws, again from McMaster-Carr.
Sliding Vise I