Further progress with the C13 chassis. Crazily, I did the trickiest bits between 1 and 2 am, this morning - after a meal out and a visit to the pub. Despite that, it seems to have gone quite well.
First, the frame overlays were attached to the fold-up inner. I used 179 degree solder, stating in the middle and slowly working outwards, soldering short lengths at top and bottom edges, to try and prevent any wrinkling of the thin overlays. The layers were held together using the two 14 BA screws, hair grips (as previously shown) and parallel jaw pliers held close to the stretch being soldered.
The result was this:
The laminated frames were joggled at the half-etched bend lines, initially using a couple of multi-layer jigs from the etch under the outer ends and the edge of my set square pressing down behind the inner fold line, generally as shown here, although this photo was taken after final folding of the chassis, as I neglected to take any photos at the time.
Unfortunately, perhaps due to the stiffness of the laminated frames and short moment arm for the bending operation, the resultant depth of joggle was insufficient and had to be adjusted by incremental further bending by hand, holding the parts of the frames either side of the joggle in parallel jaw pliers. The required amount of joggle was checked using the shank of a 1.1 mm drill bit against a straight edge, generally as shown here.
All the joggling was done with the frames in the flat, so to speak. Once the joggling was deemed satisfactory, the frame assembly was folded, by hand and in small increments at the four folds, until the frame plates were at right angles to the integral spacers. After adjustments to ensure squareness and freedom from twist, the folds were reinforced with solder, the front ends of the frames bent inwards and soldered.
Here are the folded up frames.
Trial loose fitting of some of the frame stays has revealed some design errors which will require some slight modifications to my original ideas. Hopefully nothing too drastic.
Dave.
