Recycled redwood bench
Design considerations: This bench is for seasonal outdoor use but it could get wet or otherwise abused so it had to be durable. The design was inspired by Chinese benches though no particular example was referenced. Limited material impacted leg design, allowed no apron, and dictated overall size. The seat is a full 2" thick and therefore some form of visually lightening edge treatment was needed.
Material:The redwood for this project originated in a pre-1900 carriage house undergoing substantial renovation in San Jose, Ca. These were floor joists under a garage. Much was rotted, oil-soaked, split, nailed, caked with dirt and sand, termited, and otherwise unusable. The sound bits were far smaller than the original full 2" x 8" x 16's that made up the bulk of the boards and it took considerable effort to render them usable. Pins and wedges are of Honduras mahogany.
Old growth redwood is not like the stuff you get at Home Depot these days. The color is deeper, the grain generally straighter and finer, and not many knots. In this case it was under cover for 100 years so it is dry and on the hard side - as redwood goes. End grain still crumbles mercilessly if you are not careful or if your tools are anything but sharp enough to shave with. And it has a history - like the two .32 caliber slugs we planed into.
Preparation: Removed all nails, damage, and bullets. Then my table saw with an expendable rip blade yielded 2" x 6" boards up to 8' long. The best of these were then wire-brushed and rough hand planed to clean wood on both faces (#6 Stanley equiv, enough blade exposed to get below the dirt layer) . Final selection left a bench top of 18" x 6' with just enough for basic legs and a 3" x 2" beam to span the leg assemblies. Resawing one of the cutoffs provided the saddle pieces for the leg assemblies. All stock was hand planed flat and square for final selection but there were not a lot of lay-up choices to be had.
Construction: Legs were mortised (tenon has shoulder all sides) into the seat, saddles use tenons (shouldered all sides) into the curved legs, and the beam has straight pins through the beam inboard of the saddles to counteract the force of the wedges outboard of the saddles (hence the two separate mortises seen above on the beam end). Seat boards are simply edge-glued but taking care to make sure grain direction is consistent so the glued up seat can subsequently be planed successfully.
I started with a full size template of a leg in 1/4" birch plywood and a full scale layout of leg assembly on a larger scrap of plywood. Traced the template onto the leg blanks, bandsawed rough curves, and then placed each leg on the full scale layout to transfer reference points onto the leg blank.
Toughest task was sinking mortises for the bridge pieces into the curved inner surface of each leg. It could have been done before cutting the curve, but you need to make that call depending upon how much material you will remove when the curve is cut. Not a lot of curve in this case so it might have been easier, more precise, and less destructive to mortise first.
Next challenge was smoothing the curves. For this I made a spokeshave of sorts with a 60mm Japanese plane (kanna) blade. The tool took longer to make than smoothing all 4 legs. Cutting the curved shoulders on the bridge parts was done with a flexible saw blade (kataba-style crosscut) and carefully following the traced layout line. Starting at the far end you gradually lower the saw handle until the entire curve is being cut at once. But you could easily cut straight across and then pare to the line.
My plan to use an antique half-round moulding plane to round over the edge of the seat top failed despite efforts to resurrect the plane. I need the male counterpart to my plane to recondition my plane. Saving that project for another day, I used a block plane to approximate the curve I wanted.
The kanna leaves an excellent (mirror) surface and redwood suffers a lot if sanded. I did sand with 400 grit between coats of satin polyurethane and after the final coat (with linseed oil) to knock down the sheen. I finished the leg assemblies, beam, pins, and just the underside of seat prior to gluing the leg assemblies into the seat. Once that set I finished the top with 3 coats..
Tools and supplies:
This wood started out filthy an full of metal, so it helped to have sharp but expendable tools to clean it up. The table saw took off dirty edges and rows of nails. A 14" bandsaw for the leg curves and a power drill with a 5/8" Forstner bit for the mortises. That is it for power tools.
Made the 60 mm "spokeshave"(nankin-ganna) for putting a finished surface on the leg curves and scrap wood depth gauge for the seat mortises. Popping through on those would have been bad. A 70mm kanna was used for smoothing and finish planing, a kikai-shakuri-kanna (3mm) for rabbeting out a 5/8" x 5/8" area along the perimeter of the seat as part of the edge treatment, and both a western rabbet plane (Stanley 190 or similar) and the Japanese variety (kiwaganna), and chamfer plane(kakumen-ganna). Various rip and crosscut saws (all Japanese), chisels, and a frame saw with a 1" hook tooth bandsaw blade for resawing. A triangular Japanese knife worked wonders on end grain..Bar clamps and Gorilla glue for gluing the leg assemblies into the seat. I have given up on Titebond III.