Friday, December 21, 2007

Finally Getting Good Welds

Yesterday I practiced the patch welding process again, and this time I took a lot of pictures. This is the plan:


After cutting off the end of my previous practice weld with a die grinder and cut-off wheel I used my grinder to smooth the edges and polish off most of the surface rust. The next time I do this I will paint the exposed surfaces with weld-through primer, which is supposed to help prevent rust in the joint. I also foresee a role for POR-15, brushed liberally along the joints after welding.


This is my pneumatic flanger. Got it at Harbor Freight. I will use it to bend an offset along the edge of this piece. In practice this will most likely be the edge of the original sheel metal.

At this point I ran into a problem. My nice new flanger would not flange. After a lot of fiddling around I discovered that the swivel head -- the black piece -- does not exactly swivel. It threads onto something inside. I had swiveled it enough to unscrew it enough that the jaws no longer met. All it took was a few clockwise turns and I was back in business.


After flanging. The new flange is on the left.


The flanger also has a hole punch, located closer to the body. Here I used it to punch holes one inch apart, which is about the same spacing BMW used for the spot welds around the rear window opening. You can see four of the punched out bits laying on the table. They exit through a hole at the end of the head, which is to the right in this picture.


For my previous practice I just laid the two pieces on the table. This time I decided to clamp them tightly together. The warp might be from the flanger, but I think it was from the heat from my previous welding practice. Something to watch out for.


All clamped tight and ready to weld.


After welding. Sorry, no pics of me in my welding regalia. For that I'll need someone else behind the camera. I held the gun closer to the work than before, about 1/2 inch, and held it on each spot for about five seconds. Each hole was completely filled. This is the first weld I have made that I consider good enough for the car. Notice how clean the welds are, with no flux residue. All those recommendations to use shielding gas were right.


The flip side. In practice this will be the outside. There is a mild, blue burn mark at each weld spot, which I think indicates proper weld penetration. The joint was absolutely solid.

Today I decided to practice welding with the work vertical, which is how it will be most of the time on the car. I have had people tell me that vertical welding is a lot harder. They were wrong. I laid down several perfect beads in the clear area next to the weld spots, without any problems whatsoever. Nice smooth beads with no splatter and good penetration.

Inspired by my success, I laid out and made the first bend in the piece that will replace the rusted section under the rear window. (See "I Have a Life," Oct 12, 2007). I was in a rush so I did not take any pictures. My bad. I used a heavy U-channel piece that was originally a bumper, and suprisingly straight, to clamp my sheet metal to the steel table with 9/10 in. hanging over the edge. I bent that part down by whacking it with a big hammer and a piece a 2x4 wood to spread the impacts. Many, many impacts. If the result needed to be straight this would need to be done on a brake, but since the result will be curved, which means a lot more hammering, a little stretching is not a problem at this point. The important thing is to have the two bends the correct distance apart, and the correct angle.

The shop will be closed this Sunday and again on Wednesday, along with the usual Monday and Tuesday. The next chance I'll get to work on the car will be Thursday.

One last thing. I went shopping yesterday for a cart to put my welder on. The best place in Honolulu to get that sort of thing, Kilgo's, closed a few months back. I went to Home Depot and the only thing they had was made of plastic. The good news is it won't rust out. The bad news is, welding sparks will burn holes in it. I think Sears Craftsman has what I want. I should watch for an after Christmas sale.

Thursday, December 20, 2007

Welder Up and Running

Last Sunday I set up my new welder. I ended up with a bunch of questions and I could not get the wire to feed all the way. Yesterday I stopped by Gaspro on the way to the shop and got answers. Very nice people there. At the shop I slipped off the nozzle hood and saw a short piece of old wire stuck in there. I managed to pull it our with needle nose pliers and the wire fed fine after that.

The helmet works great. Simple to set up and once that's done all I have to do is put it on. It makes welding much easier than the hand-held sheild that came With the shop's little Lincoln.

My practice welds are still not good enough for real work, but they are a lot better than before. Today I'll take pictures of a practice patch.

Saturday, December 15, 2007

Got My Welder

Day before yesterday I picked up a gas MIG welder from Gaspro. A Miller 140 with Auto-Set. Got a great deal, too. It was the last one they had, their demo unit. It isn't clean and shiny, but I figure it looks the way it will look after a day or two at the shop anyway. It did come with a two year warranty. I spent the money I saved on a cool auto-darkening helmet.

I had to buy a tank for the gas. The salesman said that for thin mild steel I should use an 85-15 mix. I think one is argon and the other is C02. I have no idea what effect changing the ratio will have. I have a lot to learn.

Another thing I had to buy was wire. I got a small spool of 0.023, the smallest size they had. The next time I'm at the shop I'll get the alloy and part number so that I know what to buy in the future. I also had to buy a pack of tips that go into the gun that matched the smaller wire. So, remember, changing wire can require a different tip.

Honolulu is such a small town that as I was getting everything ready one of the salesmen said he went to school with my son Matt. His name was Gordon. The guy who recommended I use 85-15 gas. This is not an isolated case. The same thing happened at my neighborhood NAPA store and at Starbucks in Manoa. In Hawaii, everybody knows everybody.

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