Sunday, March 29, 2009

RH tail light welded, mostly

First of all some good news. My laptop is back in action. The FreeBSD side, that is. I had to make last week's posting from Vista because the complete OS update I was performing was not finished. I went from FreeBSD 7.1-RC1 to 7.1-RELEASE and, more importantly, Gnome 2.22 to 2.24. I botched the first attempt but the second time was perfect.

I took pictures today. I thought I'd write this first, then work on the pictures.

The task for the day was to attach the patch that will form the bottom of the right-hand tail light. To do that I had to punch holes in the patch I finished making last week. No problem there except the notch I cut in the bottom was too deep, so the holes were well above to edge of the piece underneath. Not that it mattered, because the piece underneath is so warped the holes probably would not have worked anyway.

The welding went really well. I have gotten much better at holding the bead where it needs to be long enough the get good penetration. I ran through the grind and weld loop a few times until I was satisfied.

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For that warped place I ended up making a little flat piece and slipping it in between the bracket and the patch, where I welded it in place. Looks tacky, but I think it will help transfer forces from the bumper, which is what the bracket is for, into the body.

I was going to apply a first layer of Epoxy Putty so I ran through the wash and prep sequence, then I realized that I still have a lot of welding to do next week, to attach the upper half of the patch, so I held off.

The upper patch is close to ready, so I might get it welded on next week.

Monday, March 23, 2009

RH tail light ready to weld

Last Sunday's session went really well. I even remembered to take the camera. Unfortunately my laptop is unavailable due to a problem updating the operating system so no pictures until that's fixed. When it's working I'll update this post. Before starting I took some pictures of the patches as they looked at the end of the previous session.

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When I started the plan was to weld the two halves of the patch together before welding to the car. As I fiddled with the fit I decided it would be better to attach the bottom half first, then use the existing structure to align the upper. To get the angles right while off the car would be highly unlikely.

I made the lower patch larger than it needed to be to simplify shaping it. Now I had to cut away the badly rusted places on the car side and fit the patch to what remained. Along the way I had to leave a 3/8 in. border to form a flange to attach to. Midway accross the bottom I had to deal with the tab that reinforces the bumper mount. I ended up keeping most of the height on either side of the tab and cutting a large notch to accommodate the good original sheet metal at the tab. The last step was to trim off the excess on the left side of the patch.

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I really wanted to weld it in place, but it was getting late and I was tired, not the ideal conditions for an inexperienced welder. I ended up painting everything with Weld-Thru primer. Next week I'll start with welding.

Sunday, March 15, 2009

Hammering away on right tail light

Last week I cut out the pieces that will form the lower edge of the right tail light flange. Today was all about getting them to curve to match the body. Unfortunately I forgot to bring my camera so I cannot show you how nicely they turned out.

I began with the bottom half. Mostly it needs to curve away to the right. The challenge is that it also has to curve up a little in the same place. I did the first curve with the shrinker on the folded edge that will be the bottom of the Z bend. This has always worked well even with the relatively thick sheet metal I am using. In no time at all I had the patch aligning nicely with the curve in the panel, at least what is left of it. I was hoping I could get the upward curve with the stretcher. Previously it had been much less effective than the shrinker, and this time was no different. Part of the problem was that these tools flatten the work, the so stretcher was undoing the curve created by the shrinker. I got around that by hammering. Lots and lots of hammering. To save the curve I used a curved dolly clamped in the vise and a curve-faced hammer or a flat-faced hammer.

The upper half was the opposite -- the same edge needed to be stretched. This took a little longer but even so went very smoothly. The last thing I did was grind off the mating edges to bring the setback to 5/16 in. I need a clever, quick, fool-proof way to check it, as using my machinist's ruler was too clumsy. I never did get around to bending the upper half upward at the outside corner. The will require shrinking the inner edge, and before doing that it needs to be trimmed.

Next week I'll take so starting pictures, which will show how things ended up today.

Before leaving I sanded the places I painted last week with etching primer and gave them a coat of sanding primer. I decided to use brown, to differentiate the black layer. I was surprised that the paint came out sputtery and with lots of grit, like spaying old style lacquer primer too thick. We'll see next week how much adhesion I got. I suppose the can was old.

Sunday, March 8, 2009

A new solution to the tail light flange

The best thing about today was the weather. For the first time in a long time we had something close to our sunny Hawaii weather. The high was 80F! All the more special because the forecast called for more rain. It was so nice I even took a picture from my stall at the shop.


I took advantage of the nice weather to do a little work on my wife's trusty old Toyota. A few spots of rust have appeared on the top of both rear doors, where moisture collects under the rubber door seal. It was a simple job compared to what I do with the E9 but the same in principle, knock off the loose rust, lightly sand with #100 paper, clean with POR-15 Metal Klean, treat with Metal Prep, and paint with POR-15. It turned out rather nice.

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Last week I mentioned the pair of manuals I purchased from Bill Proud. Since I was in a picture taking mood I took a few of them. They even came with the correct yellow tabs, all in their place. Very nice.

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My E9 work began with a light sanding of the black primer applied last week, the goal being to reveal the high spots. Once I had a feel for the terrain I switched from #100 to #80 and did some serious shaping, stopping only when the high spots were down to bare metal.

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At that point I should have shot the bare places with etching primer, but I still do not have the knack for doing more than one thing at a time. So I planned on painting at the end of the day and switched to making the sheet metal patch for the right tail light.

Until today I had planned on making the patch from a single piece, but as I was laying it out I realized that it will require some tricky compound bends, the sort that have caused me problems before. The body panel curves away to the outside as it wraps around to join the side, and the opening curves upwards, also on the right side. The patch needs to flanged, a "Z" bend about 1/4 in. deep and with a 1/2 in. edge.

The solution I came up with was to make the patch in two pieces. One will begin at the body panel with a right-angle bend inward, and the other will form the inside edge, also with a right-angle bend that will overlap the first. I should be able to achieve the compound curve using my shrinking and stretching tools. If it gets too crazy trying to match the curve along the overlap I'll resort to using tabs.

With the new plan in place I cut two 2 in. wide strips of sheet metal and bent a 1/2 in. right-angled bend in both. I left plenty of extra material for trimming later. Not having a brake is really a drag at times like this, so the bends required a lot of pounding with a hardwood black and a large ball-peen hammer. Fortunately the shop has a sturdy steel top workbench. Somewhere along the way I latched onto a large slab of thick steel which I use when I clamp pieces like this to the table. It works, but a brake would be much better.

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At the end of the day I wanted to shoot the bare spots with etching primer, put some POR-15 Epoxy Filler in a few low spots, then finish with a coat of sanding primer. Unfortunately I did not allow enough time, and the etching primer ended up where I wanted to put the filler. I waited as long as I could and tried to apply some filler, but I'm afraid it will not stick well.


Sunday, March 1, 2009

Searching for body lines

First thing to report is the receipt of a two volume set of original BMW "Big Blue Books." Repair manuals for the E9, Band 1 and Band 2. I bought them from a fellow E9 enthusiast I met on the mailing list, Bill Proud. Terrific guy. I'm sure these will be invaluable later in the restoration.

Today began like last week. Lots of sanding. This time I was more careful to look for the curve in the body as it wraps around under the tail light rather than blend the filler into the sheet metal. This takes time, but the idea is to avoid going too far and having to do it over.

The best way to do this is by feel, followed up by visual inspection. At first, when the filler is lumpy, it is hard to feel anything, but as the filler starts to smooth out the ebb and flow of the surface can be felt through the sanding block.

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As I approached perfection I found it hard to see the highs and lows so I shot the area with Evercoat Acid Etching Primer. Supposed to help anchor paint to bare metal, and I had a lot of that, but what I was after was a continuous, single color surface that would reveal the high spots. This primer was a light tan color. To prep the area I did the usual POR-15 Metal Kleen and Metal Prep routine. The paint needed twenty minutes to dry, so I ate lunch.

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After more work on the high spots I decided to see how much help the other primer I had purchased would be in filling in the low spots. In my youth we used sanding primer, which was lacquer based. It had to be spayed from a gun, but it was dirt cheap and dried almost instantly. Using a gun where my E9 is now is somewhere between awkward and impossible, so I bought some aerosol cans of SEM High Build Surfacer Primer from Redline Automotive, the local auto paint supply. One can each of black, red and white, the idea being to alternate colors to help judge how far to sand. This stuff is supposed to work well with modern base coat/clear coat paint systems. It wasn't until after I had the first tack coat on that I discovered in has to dry for an hour before sanding. By then the shop would be closed.

I decided to press on and paint the entire section I had been working on for the last month. I gave it three heavy coats and even though I was using a spray can there wasn't any drips or runs. Pretty good stuff.

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Since I was done sanding for the day I decided to get started on the right tail light. This one has even more rust damage than the left side. Virtually all of the lower flange is missing. There is a doubler on the inside where the bumper bolts attach which I can use to anchor the new skin, but to use it I would have to grind away the upper half inch of original but badly rusted sheet metal. I used the remaining time to do that, finishing with the Metal Kleen and Metal Prep treatment.

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I think it is a good thing I got started on a new section. Now I can alternate between work sites while the other site is waiting on something to cure. It won't be long before I'll be attacking the front.