I'm just starting to build a roadster for myself. One of the key elements the design is based on is the grille shell. The shell needs to be shortened 11 inches from stock, and I want to add a flange at the rear of the shell-this will add strength, and provide a convenient mounting surface. I also want to fill in the bottom portion of the shell (the original was notched out to fit over the frame), and eliminate the apron that hid the front crossmember and spring on the original '32 Ford.
Brookville Roadster makes an excellent reproduction '32 shell in steel, and I considered modifying one of these shells to meet my requirements, but in the end, I decided to make a new shell from aluminum. Most of the body of my roadster will be aluminum, and I want the grille shell to match!
Although I've spent most of my life shaping sheetmetal, this job brought some real challenges to the table. The '32 grille shell has a tightly radiused lip that surrounds the grille, and this detail would be very difficult to form freehand. After considering several options, I decided to make a combination buck/hammerform, which accurately models all the contours of the shell, and which has hard steel surfaces I can hammer the aluminum against to form the grille recess and the rear flange.
As you go through the photos, you'll see how I went about making the buck/hammerform, how I shaped the aluminum pieces, joined them together, and did the finish work. Although this is a fairly advanced project, the techniques used here could be adapted to many street rod projects.
The first step is to make...
The first step is to make an accurate fullsize drawing of the front view of the shell to get the proportions right for my application.
Once I had the size determined,...
Once I had the size determined, I made a template from aluminum plate that defined the shape of one side of the grille opening.
With all the bending completed...
With all the bending completed on both pieces of the bar, they were trimmed, tack welded together, and checked against the fullsize layout drawing.
The next step is making stanchions...
The next step is making stanchions to hold the steel structure the proper distance from the medium-density fiberboard that will be the back structure of the form.
The grille shell will have...
The grille shell will have a flange around the grille opening, and my form needs a strong, accurately positioned surface for holding this flange.
Here I'm using a contour gauge...
Here I'm using a contour gauge to measure the curvature of the reproduction shell in several key areas.
Here's the completed buck/hammerform....
Here's the completed buck/hammerform. It allows me to envision the finished part, and it provides a sturdy, accurate surface to fit each piece of sheetmetal against.
Here I'm making a paper pattern...
Here I'm making a paper pattern for the top piece of the shell.
Although the parts could be...
Although the parts could be completely smoothed with a slap hammer and dolly, I'm using a benchtop English wheel here to speed the process.
A piece of .063-inch thickness...
A piece of .063-inch thickness 3003 H-14 aluminum is cut to size, and softened by heating to about 800 degrees F. (This process is called annealing.)
After the first wheeling,...
After the first wheeling, the part is considerably smoother.
A shrinking machine is used...
A shrinking machine is used to help shape the tightly curved areas on the edges of the panel
Once the part is completely...
Once the part is completely smoothed out, a mallet is used to tap the leading edge over the round bar, giving it the proper curvature.
The sides have much less shape...
The sides have much less shape than the top, so all they need is some shrinking on the edges, and a little "tune up" in the English wheel.
Here the leading edges of...
Here the leading edges of the grille shell sides are being worked with a mallet to form the grille shell opening.
Now it's time to make the...
Now it's time to make the pattern for the bottom of the shell. Again, this part will be made 1/2-inch oversize all around.
With the top shaped, I can...
With the top shaped, I can make the pattern for the sidepieces. This pattern will overlap the top piece by about 1/2-inch.
A piece of aluminum is cut...
A piece of aluminum is cut to size, annealed, and worked with the shrinker to start the shaping process.
The English wheel is used...
The English wheel is used to give the panel its final shape and smoothness.
Once the panel fits the buck...
Once the panel fits the buck nicely, the leading edge is curled in the beading machine.
Again, drywall screws are...
Again, drywall screws are used to hold the panels tightly against the buck, and the joints between the sides and the bottom are scribed and trimmed.
Now we'll start on the recess...
Now we'll start on the recess for the grille. A bending brake was used to put a 1/8-inch flange on the bottom of two strips of aluminum.
Clecos (quick-release fasteners)...
Clecos (quick-release fasteners) are used to align the aluminum strips, and small clamps are used to hold them tightly against the form while they are worked against the round bar.
Any areas that overlap are...
Any areas that overlap are trimmed, leaving a nice, tightly butted fit, and the parts are tack welded together.
After tack welding, any areas...
After tack welding, any areas that aren't completely flush are adjusted with a hammer and dolly.
A disk sander is used to knock...
A disk sander is used to knock off just the top of the weld bead, then a vixen file is used to refine the entire surface.
The last step is forming the...
The last step is forming the flange on the rear of the shell. I screwed pieces of 14-gauge steel plate to the back surface of the form to withstand the hammering and heat.
The metal is much easier to...
The metal is much easier to flatten while it's hot.
After flattening, the flange...
After flattening, the flange is sanded smooth. Now the form can be disassembled from inside the shell.
Here's the finished product....
Here's the finished product. Notice how well the aluminum shell captures the flavor of the original