Q. I am building a replica 1930s-40s era champ car from scratch. I built the rear "bustle" section without a headrest, but I had always planned to add one after the main body section was formed. Now I am faced with the task of grafting on the headrest, and making it curve rearward with an ever-diminishing radius.
I see three possible approaches, but I'd like your opinion on which is best: One, rolling a straight conical section, shrinking the edges to get it to conform to the body opening, then flaring it out at 45 degrees to meet the body with a butt weld; two, build a buck and hammer a single piece of metal on a shot bag, then smooth with the English wheel; three, make the headrest from two pieces of flat stock cut in the general arc of the body, then shrink the top edges together, and flare the bottom edges out into the body.
All these approaches involve cutting out a wedge-shaped piece from the top of the body and flaring the edges of the opening to about 45 degrees to mate with the headrest.
I have an extensive build thread going at the H.A.M.B. under "1930's Era Champ Car—new project". Thank you for your advice, and I wish you continued success with your metal working endeavors!
Greg Koesel, aka "The Frenchtown Flyer"
Via the Internet
A. I must say, that is a particularly cool project, and you have done a great job so far.
The headrest could be made in any of the ways you suggested, but I have a very strong preference for the last one. Since the headrest would be made from two pieces of metal, there will be one additional welded seam. While this joint entails additional work, there is a huge advantage in the amount of metal shaping involved.
The first step is making a pattern, which has to allow enough metal to create the curls needed at the top and bottom of the panel. You can make a pattern from chip board or heavy paper, and try it into place on the body to check its size and shape. Be sure to allow enough material to go slightly over the centerline.
Once you've cut two pieces of metal from the pattern, I'd start with a mallet and sandbag, bulging the metal out along a line about one-third of the way down from the top edge. Work into the bag along this line, and then start working slightly upward and downward from there. You'll need to correct the front-to-back contour frequently as you do this work. Work in this manner until you have about a 30-degree curl on the top edge of the panel.
Next, I'd shrink the top edge to start pulling it down. In addition to shrinking, you'll have to do some curling of the edge as well, but the goal is to keep moving that edge down until it is horizontal, and of course the contours of the entire panel need to be kept in control as you do this.
Once the top half of the panel is close to the shape you want, I'd smooth it in the English wheel, and this tool can give a little "fullness" to the side of the panel, as well.
The last step is to put the outward curl on the bottom of the panel. I've done this by selecting a piece of steel tubing of an appropriate diameter (3 to 4 inches is typical), and carefully hammering the bottom edge of the panel over the tubing, which will create a beautiful outward curve.
I think you'd benefit from making a wooden buck for this project, otherwise it's pretty difficult to get both sides shaped symmetrically, and to get the centerline of the headrest to match the centerline of the car!
Contact me again if the going gets tough.
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