How to Fabricate a Cowl Panel From Scratch

Posted: September 2, 2016 By: MattM

Ok, so I know the Ford Model A stuff has been heavy in my posts lately, but like many of you I started by wanting one to build and then somehow I’ve ended up with three of them in a year. They multiply I tell ya! Anyways I somehow ended up with this ’29 Model A Roadster carcass I want to build a little replica-racer out of. It was cheap, the bones were there and I figured I could build it up when I found some non-existent free time. I’m a little stubborn and although I could buy an entire new steel replica body, or all of the panels new to make this car all solid again, I’d rather build the panels I need from scratch and bring a close to 90-year old car back from the dead for very little money out of my pocket. I decided I wanted to start in the front of the body and work my way back. The side cowl panels are almost ALWAYS rotted out on the bottom of these cars and after I looked at the remains of the originals I decided I could easily tackle making new panels for only a few bucks in sheet metal. One of my favorite things about cars of this era are how simple and small they are so you can break the project into small sections and piecemeal it as you go.

cowl1

cowl2

I started by removing the left cowl side and ripping off a piece of plain masking paper. In this instance you don’t want to use thicker stock like cardboard or butcher paper because it doesn’t bend as easily when trying to form the paper around the original part. Keep the thicker stuff for floor pans, brackets, and the like as they’re great for that!

magnets

Photo Aug 16, 10 17 26 AM

Photo Aug 16, 10 17 37 AM

Photo Aug 16, 10 22 52 AM

pencil pattern

Photo Aug 16, 10 33 54 AM

I laid the paper down over the panel began placing stitch weld magnets around the perimeter of the panel; pushing the excess paper off of the edges so that it was flat and tight in the center of the panel. As I bent the paper around the pattern the paper bunched and folded around the edges. Wherever the paper fought folding over I ripped a straight line in the paper up to the bend line. I then pushed the paper down and watched what it did. If the paper overlapped it told me the metal needs to be shrunk in that area, if the cut opened up it told me I need to stretch that edge. I then taped those cuts in place when they felt relaxed and let the paper bend around the edges. I then took a plain lead pencil and ground the side off of it to expose the lead and used the side of the pencil to put lines on the outer edges of the panel. This gives me my outside shape. I also traced out the lines for the step in the panel and cut the paper in the corners where the panel was cut. Finally I traced the edges of the flanges so that the width of the flanges were accounted for in my pattern.

Photo Aug 16, 11 17 02 AM

Photo Aug 16, 11 18 03 AM

Photo Aug 16, 11 23 27 AM

With the pattern drawn and cut out I notated on the pattern at each cut if it was a section that needed shrink or stretch. I then fixed the pattern to a fresh piece of 18 gauge cold rolled steel with the stitch weld magnets and traced out the outer most perimeter of the pattern. This was the edge of the flange around the panel. I needed to also transfer the bend line and the step in the panel to the new steel. I used the automatic center punch from our sheet metal layout kit to punch divots through the paper and into the metal every few inches on the pattern. Finally I transferred my shrink and stretch marks to the metal. This allowed me to remove the magnets and paper and connect the dots of the bend and step lines onto the metal. I put a note on the step line so I didn’t get lost when working on the pattern.

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stepbead

I started by putting a the offset dies in the bead roller from our forming die kit. I set of the offset of these as tight as I could be to make a sharp step in the panel. I then tightened the dies down by hand so they touched. This would leave a step the thickness of the metal in the panel. I rolled the step in the panel in one pass. This was the only time we will need this die.

tipping dies

tipping1

tipping2

tipping3

tipping4

Since the two of the three bends in the panel were on a curve we couldn’t make them with a standard metal brake. I decided to use the sharpest die in the forming die kit for the bead roller on the top. Normally this die is used with the soft polyurethane wheel, but the original part had a pretty sharp, defined bend so I opted to use the flat section of the rounding die as the bottom roller. The dies can all be interchanged to get custom effects in metal. I set the dies up so the top die was hand tight on the flat part of the bottom die and I ran the metal through the bead roller. For the first pass I only put light upward pressure on the panel as we cranked the bead roller. This is to mainly score or set a line in the panel on our bend line. By doing this you give yourself a little track to run the panel on as you progressively push up on the panel and bend the flange to the desired angle. For these flanges I need them to be 90 degrees so I ran the panel through each side about three times in total; pushing up the panel more each time.

shrunk

cowltucks

Now that the panel had the step and the bends in it we are starting to get something that resembles our original part. I tuned up the corners of the part with the hammer and dolly to get the bends more crisp. Now viewing the edges of the panel they closely told a story similar to our paper pattern. The one large sweeping edge needed the tucks shrunk that had formed. I wanted to address those first before we stretched.

shrink1

shrinkin2

I put the panel in the shrinker and “snuck up” on the shrinks working on either side of each tuck until it flattened out. I didn’t want to move the metal much further than flattening the flange out. You can see above how the ripples or tucks have now all been flattened out. I did the same process to the bottom edge that also called for shrinking or smoothing.

profilegauge

profilegauge2

profilegauge3

stretch1

With the panel getting close in shape I decided to check the flow of the panel with an adjustable profile gauge. I set the gauge to match the original panel and checked my new panel. It was very close from top to bottom where we shrunk, but the top had almost no shape to it. It needed stretching to create a belly in the panel. I slowly went over the edge with the stretcher; barely moving the metal. I then checked it to the locked profiled gauge and found the edges needed a little more stretching. After a few passes I got the panel fitting the gauge quite closely and I was ready to trim all of the edges and test fit it on the cowl.

Photo Aug 17, 10 19 58 AM

After clamping it to the cowl I can see I need to tune up the top profile a little bit to get the panel gap better. For a first test-fit it flows with the A-pillar nicely and shouldn’t take much to get it fitting 100%. Next I’ll drill holes in the flanges to locate the panel to the rest of the cowl and do the final adjustments once I’m ready to fit the body to a frame.

Whether you’re building an entire fender or a small part like this, the process is basically the same. You need to make a paper pattern to give you a road map for how you need to attack the shaping of the panel. It just takes some thought and experience to figure out the correct order of the steps you need to take to make the project go smoothly. I’m still learning that myself, but every project teaches you something new that you can put towards the next!

-Matt/EW

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14 thoughts on How to Fabricate a Cowl Panel From Scratch

  • Great job , looks nice
    Enjoyed the post,
    A good project would be rear wheel opening
    Panel replacements
    Including inner wheel
    Fenders as well ex. 2003 ford f250. Thanks

  • Terrific teaching tool. I would have liked some comments between some of the steps, would be easy-er to follow, instead of all at the end of the step. I never would have thought to shrink between the folds to flatten them. Thanks How about a demonstration of all the bead roller dies, it would be easier to see which ones I want if I could see each one in use.

  • Have you ever thought about having a hands on class to help us want to be fabricators. I own all most all your tool and could use a little help now and then

  • Hi Charles, We do offer hands-on classes at our retail stores in Alsip, IL , Parma, OH. , and Pottstown, PA. Their contact info is at the bottom of our homepage. Give them a call and they can let you know when the next class is coming up.

  • Thanks for the comments Jim, we’ll do our best to get some more videos and tech articles up showing the process here soon. The dies can all be interchanged to do different things so the combinations are almost endless!

  • Unfortunately we only have classes in our retail outlets but we try and make the live broadcasts as interactive as possible!

  • Hi Ben,

    Unfortunately we did not film a video on that as we were in the middle of a remodel and our studio was shut down. Sorry!

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