Sunday, July 27, 2008

Too hard too fast

Another short note about a busy day. Today I finished cutting notches in the last patch and painted the underside of all three with 3M Weld-Thru Primer. I decided to do the hard part first, the farthest to the right. As I set up to weld I realized that the curvature of the patch still did not quite match the opening, but I thought I could pull it into place. I tacked it into place at the outboard end and used a small vice-grips plier to hold the inboard end in position. Just when I got it right the tack welds broke. I'll have to try again next week.

Three finished patches, bottom view -- the solid edge will be vertical, on the bottom.


Flipped around 180 deg. so you are looking at the top with left-right reversed.


Underside painted with 3M Weld-Thru Primer


Sunday, July 20, 2008

Preping More Patches

Just a short note to say I spent the day working on the remaining three patches for the rear window sill. Lots of cutting and filing. I was hoping to get all three done and painted with weld-thru primer but time ran out.


My experiment with welding POR-15 has caused me to change plans. For these three patches I will use 3M 051131-05917 Weld-Thru II primer. The label on the aerosol can reads "A Weldable, Corrosion Resistant Coating." The good news is that drying time is rated at 5-10 minutes, so I can paint and weld next week, all on the same day. The bad news comes in two parts. First, the can recommends applying 3-4 coats of the same paintover, followed by a layer of Rust-Fighter I. Or, as a second option, remove all traces of Weld-Thru II prior to applying plastic filler. Neither choice is an option in this case, because the back side of the patch ends up in an enclosed box section.

During the week I picked up a fire-proof blanket from GASPRO, because last week while welding in the trunk area I set two rags on fire. I hope I don't get a chance to see how well it works.

Friday, July 18, 2008

Bringing It All Together

I made a useful discovery last Sunday. Don't paint something with POR-15 that will be welded. I was going to say an important discovery, but that sounds overly dramatic. When POR-15 gets hot it gives off wicked smelling fumes sure to make a hypochondriac pass out, and when it gets really hot it burns.

And now for some good news. I did my first weld on the car. Talk about passing a milestone! Break out the Champagne. Oh wait, this is a German car. A case of Heineken would be more appropriate.

The week before last I did work on the car, but I didn't get enough done to warrent a blog entry. Actually I spent a lot of time talking to Gene about the swap he has in mind for his BMW station wagon. What work I did was all prep for this past Sunday. Mostly working the patch to get the best possible fit. I finished by painting what would be the inside of the patch with POR-15, because after it is welded on there is no access to that side.

One bit of disappointment: Some POR-15 I had applied weeks ago was peeling of in two places. I was looking for nicks caused by repeated trial fitting of the patch, especially when it was one long piece, and in the process found two places a bit smaller than my fist that peeled off rather too easily. I made sure I roughed up the surface to get a better stick before repainting. When it comes to painting, surface prep is everything.

My idea of the wire hook to pull one end of the patch up into position worked great, only it was cumbersome with welding gloves. I set up my welder Using the settings worked out on practice welds and got good results. Some spots didn't bite and create enough penetration. I think I was holding the tip too far away, or else too close. I definitely agree with advice others have given me, that grinding down the welds takes longer than making them.

I made sure each of the patch segments got at least two good spot welds. The last thing I want is to have movement here as that will ruin the finish in a highly visible location. I finished with an application of epoxy putty all around the edges and along the gaps between sections. Later on this will all need to he filled in a lot more, but I want to see how this much turns out first.

Like I said, painting the inside of the patcb with POR-15 before welding was a mistake. For the next one I plan on using weld-thru primer. I am also thinking about drilling a series of holes along the bottom of this hollow box section for applying rust proofing. I'll need rubber or plastic plugs too.

I had a inspiring neighbor that day.

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The first patch to be welded onto the car!

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