2014.08.11. I’m back from my summer travels and returning to the Schall von Bell project. I’m at the point where I should be designing the tube. My mirror is ready for a star test, and for that I want a tube. The mental image of the tube involves upper and lower tubes connected by struts.
2014.08.22. I’ve made some wood purchases: some maple plywood, 1/4″ and 3/4″ was available at the local home improvement store. From a nearby hardwoods lumber yard I found 5′ of 12″ wide 4/4 hard maple and about 6′ of 6″ wide 4/4 soft curly maple. In my mind’s eye I see the ply wood used for the mount, the LTA, and the UTA rings; the hard maple, for the altitude trunnions; and the curly maple to connect and support the UTA. Remainder from the hard maple board could be used to hold the trusses. I also got four six-foot, 1.24″ dia, pine dowels for the trusses.
2014.08.25. I’ve started experimenting with finishes: BLO and shellac with and without dyes. In the photo, the dye is aged maple Transtint.
2014.09.06. I took the hard maple board, which was rough cut, to a fellow ATMer at Chevy Chase, a contractor in Alexandria, who let me use his planer and belt sanders to begin preparing it.
2014.09.09. I routed the altitude bearing arcs out of the maple board this evening. Taking Highe’s advice that one could get away with less that 180° and with some conventional wisdom that the larger the radius is relative to the diameter of the tube, I went to the circle calculator. With a sagitta of 12.625 (the board width) and a desire for a roughly 165° arc, a created a jig that placed the center point of the router’s circle jig 2.31″ off the edge of the board. The radius of the circle ended up 14 7/8″. There’s some error, to be sure. And there was a little jostle in the routing, which may lead me to putty up 1/16″ or so on part of one of the arcs. But once I finished, I couldn’t help but admire their beauty.
2014.10.05. I continue thinking my way through coloring the wood. I feel myself divided by two different sets of desires: one, a “close to the wood” instinct; another, bauhaus. The former has led me to use BLO to pop the grain of the solid maple, to be topcoated with a wiping varnish; the latter, to experiment with primary colors for the plywood. The plywood is maple; so I’m mulling over using very faint dyes, yellows and reds, on the plywood and perhaps black on the pine dowels.