Skin f-up.

March 24th, 2014

Well, that all went wrong in a big way. It turns out when we put the sink back on the car to finish wrapping the top egse nothing lined up anymore. Somehow the rear fold was now too far forward meaning the skin couldn’t be pulled onto the frame. We think the reason was that the annealing wasn’t very good making it rather hard to bend meaning lots of hammering. During all the hammering something moved, the tail probably lifted up, meaning the fold was in the wrong place.

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You can see the back fold is rather long. There shouldn’t be that much material bent over. The bend line is about 3/4 inch too far back.

So, what to do. Unfold it all. Was all rather depressing really but Joss started me off re-straightening the metal. We hammered it into that shape so it’s perfectly possible to hammer it out again. Basically by hammering VERY hard on the edges you can stretch the metal (undoing the shrinking done to make it that shape) then lots of hammer and dolly work (and lots of reannealing) will smooth the skin out again. There are a few splits and some of the welds are a bit dodgy so I will need to reweld things. I might also have to patch in a few extra pieces of aluminium but the welding isn’t an issue now.

This is the stage I am at now.

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Starting to get back to the original shape. Since we know the edge will be folded around again I have left that a little bent over already.

It’s quite amazing how you can just change the shape of the metal, put in then remove curves, all with a hammer and dolly. I am no where as skilled it it as Joss is but I am starting to get a better feel for it.

As all this was so dispiriting I worked on some other things too for a break. I dismantled (as far as possible) and cleaned and painted the horn I bought. I also found a sweet tin as a back for it. It isn’t deep enough so I made a temporary plastic ring for it to sit on. I will try to find something more suitable later.

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The other thing I found is the spring that the electromagnet pulls on to strike the rod attached to the diaphragm is cracked. Not sure how to fix that. You can’t really weld it. I might be able to make a replacement piece, perhaps from some spring stainless steel I have. The only thing I could think of made from blue spring steel large enough is a piston ring compressor I could cut up maybe.

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Tomorrow more hammering on the skin I guess.

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