Workbench Wednesday — Bench #2 , 1990, “Final” Version

Building on what I learned from the initial prototype of the portable restoration workbench I charged ahead with a “final” version.  I say “final” in quotes because this concept is one I have continued to tinker with even to this day, and a late entry in this series four or five months from now will focus on the most recent one.

For this first final version I used the same structural strategy for the top, modifying the stock weight being the only real modification.  On this second iteration I used 3/8″ A/C plywood for both the faces and ribs of the torsion box top rather than 1/4″ and 3/4″ luan for the same purpose on the prototype. Making the box approximately 3″ thick and placing the ribs in a 6″ x 6″ grid achieved a satisfactory result with essentially no change in weight while yielding a stout structure. In fact, I could do some pretty serious joinery and carving on the bench, which I couldn’t do with the prototype.

I wanted a large-capacity vise on my bench, but there was no point in defeating my original purpose by building a lightweight bench and then installing a heavy vise on it. The vise(s) I built opens about 12″ and employs aluminum threadstock for the screws, tapped holes in the endpiece of the top, and 2″ x 3″ x 24″ wood jaws. The screws pass through same-sized holes in the movable jaw, and terminate in simple wooden handles passing through holes drilled in the ends.

One pretty dramatic change in this function was to switch from standard steel threadstock to 1-inch aluminum rod stock that I had cut at a local machine shop (I already had the aluminum rod stock in my scrap barrel).  It’s been a long time since this project but I recall paying $25 for the job.   All it took was to set up the pieces in the lathe and cut the threads with a single pass, along with a single groove above the threads for some retaining collars.  I’m guessing it took ten minutes maximum, so $25 for a quarter hour of machine shop time sounds about right.  It might have been $25 for each pair of screws, but either way it seemed pretty reasonable.

My procedure for incorporating the vise into the bench top involved drilling oversized holes in the internal grid but not the added fixed jaw, so I couldn’t assemble the box all at once. I cut my grid pieces and glued them to one face of the torsion box using 315 gram hot hide glue, which was the adhesive employed throughout the project. After laying out for the vise screws, I drilled holes through the fixed jaw (the torsion box end pieces) to tap-out and received the threaded screws. I was unsure whether holes the same size as the aluminum rod stock used for the vise screws would be large enough to allow the screws to go through the grid members, given the inevitable wobble in the screws. To be on the safe side, I drilled larger holes through the grid to a slightly longer distance the desired vise opening dimension. The vise screws would then pass through these openings as the vise was closed. After I was sure the vise was fully operational, I glued the second face on the grid and the top was complete.

By fabricating simple leg end units with long folding diagonal braces, the problem of too much shimmying parallel to the long axis was overcome on the final bench. The leg units were fabricated from the clearest 2x construction lumber I could find, and the folding braces from 1/4″ x 1″ aluminum bar stock with 1″ x 1″ aluminum angle stock for the mounting brackets. The slightly heavier face plywood made it easy to screw all these elements to the underside.

The leg units were not installed symmetrical relative to the short axis, but rather were off-set by half the leg width so they could fold up next to each other rather than on top of each other. This way, the table could become a remarkably compact unit which needed absolutely no assembly or disassembly; it could just be folded up. Following final assembly I added a snap-on strap for carrying the bench like a large suitcase. By throwing the strap over my shoulder, I could easily carry the bench for long periods of time and maneuver it through pretty tight quarters.

Next week, some accessories.