1/6/2008: Metalwork 10: A new year, and still more rust repair..
This entry will focus on the repair of the rust spot at the bottom. I actually did this work gradually, during the period from August to early January, but decided to save it for one post.
Looks minor, but once I started looking, I found that there was a larger area where rust was developing, and a large dent. I kept cutting until the metal was nice and solid.
There is an inner and an outer layer to this area of the car. This inner layer patch was made in two pieces, and as you can see, both have to have complex twists. It was very challenging to make, and took me about 3 attempts to get right.
Once I got it to fit, it was tacked and butt-welded into place:
This panel was shaped on my english wheel, using a the “go cart slick” technique to form the curve from top to bottom. This works by using a rubber wheel to press the metal down against the curved lower anvil, imparting that curve to the panel. This is different from the normal usage of an english wheel, where your goal is to sandwich the panel between two hard metal wheels and squeeze it to thin and stretch the metal, which adds shape.
Using the soft upper wheel causes the panel to bend (in arrangement), rather than being squeezed and changing the surface area (shape) of the panel.
The result is somewhat like a slip roll, but you can put a side-to-side bend into a panel of any length, as long as you can move the panel back and forth in parallel straight lines.
The curved lip for the edge was formed using the tipping wheel i’ve described before, and then fine adjusted the curviture by tweaking that lip with my shrinker-stretcher.
The lip at the bottom was bent on a small benchtop sheet metal brake.
It took many hours to fine tune the patch and the opening in the car, to get a perfect fit and butt-weld it into place:
The inner and outer layers don’t contact each other completely, so a small patch was needed to fill the gap:
Just a little more grinding to do, and a small hole that needs to be filled, and then I can finally call this patch “done”.