Skin cleanup

I managed to make it out into the shop for short while Tuesday night.  I had a couple of things on my to-do list for the night: Fabricate spacers for the center bearing, and clean some of the well-embedded sweaty hand stains from the skins, especially on the h-stab from before I made a habit of wiping the skins down with acetone after every work period.

The spacers turned out to be a bust.  I’d previously picked up a couple pieces of 1/4″ ID steel spacer stock.  The first problem was figuring out what thickness they needed to be for each side of the horns.  There’s too much stuff in the way to just get the calipers in there, so that’s out.  I ended up sort of eyeballing the calipers against the gap and using that as a starting point.  I made the initial rough cut by chucking the spacer in a drill and spinning it against a hacksaw blade clamped in the vise.  This gave me a nice straight cut, though it was messy and needed a good amount of cleanup.  I chucked the cut piece in the drill and spun it while going to work with a file.

A quick check showed that it was a good bit to thick, and this is where the spacer fabrication procedure got ugly.  I couldn’t figure out a good way to carefully trim down the spacer.  I tried spinning it in the drill while hitting it with a file, but that was going extremely slow, and it would have taken forever to get the size right.  So I unwisely went to work on the spacer with the bench grinder.  That got the amount of material I needed off quickly, but now the ground end was no longer square.  I tried to fix that by spinning it in the drill again and working with a file, but that didn’t go well either.  Finally I decided to put the spacers aside and move on to cleaning the skins.

The basic problem here involved skin oils, and sweat in particular, getting on the skins.  Some time back, I set aside a skin for a few weeks, and when I picked it up again I could see where the alclad was marred in some suspiciously hand-shaped patterns.  Some work with a rag and acetone cleaned things up a bit, but it was obvious that the sweat had done damage.  From that point on I made a point of always wiping down any skins after I’d been working on them.  Even that isn’t a perfect solution; it tends to leave ugly streaks on the skins that are better than sweat corrosion, but still ugly.  In any case, I hadn’t learned this lesson when I was building the h-stab, and it had some pretty ugly spots.  Besides the cosmetic issue – which is easily discounted by the old “the paint will cover that up” line – I was worried that corrosion might continue as the stab sat in storage.

So after going to the VAF brain trust, I found a simple answer: aluminum polish.  On the way home from work, I stopped by the auto parts store and secured a can of Mothers aluminum polish and some bonnets for my orbital buffer.  A good attack of the skins finished with a vast improvement.  There are still some light scratches and marred spots, but the bad sweat corrosion spots are gone, and things look great again!

This procedure probably wasn’t really necessary, but it made me feel better and only cost about an hour and a half of my life.  I can deal with that.

As for the spacers, I’ve decided to get some aluminum pieces to use instead of steel; those will be a lot easier to massage to the proper size.  I also figured out a good way to measure the gap for the spacers: I have a set of feeler gauges out in the garage somewhere.  They should be long enough to get into the gap, and I can stack them until they fill the gap, and then use the calipers to get a proper measurement of the gap. (or just transfer the measurement directly to my spacer stock, we’ll see)

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