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75. Rivetting Stuff

20/10/2013

I have a confession to make.

When we looked at the drawings for the wings, we weren’t as thorough as we should have been. The steel tubes that form the periphery of the wings are held in place by little strips of very thin steel (called clips) that wrap around the tube and lie flat on the surface of the ribs, which are made of plywood with small spruce capstrips on top and bottom. We assumed (since it’s normal practice) that the thin metal clips were held onto the ribs by lots of little brass screws, and I’d offset the clips with the tops slightly longer than the bottoms so that the screws wouldn’t meet in the middle, even though this wasn’t shown on the drawing.

So I was a little miffed, when I was going through the parts list looking for something else, to find that this called for the attachment to be done by copper rivets, using 2mm copper wire.

As you know, we’re trying to make this as close to the original as possible, so although the brass screws were perfectly satisfactory it did look as if we should at least give the copper rivets a go. The idea is that you drill a 2mm hole right down through the rib, passing through the top and bottom bits of the clip, and then cut off a short piece of copper wire and post it through, then hammering the ends down until they sit more or less flush with the metal clip.

Trying a dummy run on a piece of thicker steel was a great success, and the end of the copper wire formed a nice dome and was obviously quite secure. So I plucked up my courage and picked the centre rib in the centre section and removed the screws, before drilling a 2mm hole right through from top to bottom. It’s quite a long hole, and since most of it is in wood (either capstrip or ply) it wasn’t very easy to get the copper to pass through neatly, but it did so eventually. But hammering the ends over didn’t really go to plan. The wood didn’t support the copper and it tended to bend in the middle. The ends sticking out then bent over, rather than forming a nice mushroom head, and although the resulting joint is perfectly secure, it was fiddly and time-consuming to do, and didn’t look very good, so I’ve decided that since they used hundreds of the brass screws to attach the capstrip to the rib (those ARE on the parts list!) on the shop floor they simply carried on with the screws and ignored what it said on the parts list.

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From → Building, Technical

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