Art & Inspiration Kirkham Motorsports University Making a Bronze Coupe Fender

Hey Guys,

We had a customer who asked if we could make a Coupe from bronze. So, we started with a fender.

We are now posting how we make our cars here at Kirkham Motorsports. We are posting YouTube videos discussing CNC Machining, Metal Forming, and Advanced Manufacturing Techniques. We call these videos Kirkham Motorsports University.

As always, I'm happy to answer any questions.

David

 

neat

 

Beautiful workmanship.

 

Thanks!

David

 

Thanks! I appreciate the kind words. We use the same process on many of our aluminum parts for our cars.

David

 

Hmm!

 

Wow... really cool to see what you guys are up to down in Provo.

 

Nice work, how many hours do you have in the fender.

 

Wow! Very informative. Beautiful finished product. Did you scan a car body to create your solidworks model?

 

Our Annual Open House is on the 19th of February. We would love to have you stop by. People fly in from all over. It is a great way to shake off the winter blues and get ready for a fantastic summer of fun!

David

 

It takes about 8 man hours to make the fender and 8 hours to polish it. This doesn't include the time digitizing the car, machining the dies, or making the stretch form. As you can tell in the video, the stretch form we made is really quite simple. Anyone can make one with a little time, determination, and creativity. They are not expensive to make. We have made dies out of wood, aluminum, iron, fiberglass, steel, just about anything.

The sections are welded together, just like our aluminum cars. Silicon bronze, alloy 655, welds like a dream--but it is very hard so it is quite difficult to form.

David

 

Thanks for the kind words. I do appreciate them.

We used a Faro arm to digitize the body. We converted the digitized points into an .iges file and imported it into Solidworks. We then take the Solidworks file and import it into Surfcam to generate the machining code to make the die.

David

 

Metal artists for sure.

 

Great stuff...................

 

Wow thats beautiful. Very nice blend of old and new technologies. Do you anneal aluminum before working it as well?
I also enjoyed your cnc cobra chassis you posted here before. You kept the body as an independent element in terms of the structure. If you had wanted to use it as a stressed part of the structure would that have worked (for instance using rivets) -do the aluminum welds have enough integrity for that or would you have to heat treat the body before doing that?

 

terrific workmanship! a BIG thanx for sharing the process with us.

 

that's insane! beautiful work!

 

Interesting process.

Compared to Aluminum, how much longer
would it take to make a complete body in Bronze ?

 

jesus that was awsome to watch ....the finish on that was perfect

 

Thanks so much for the kind words.

David

 

I'm glad you liked the billet chassis. I'll comment on that one in a bit.

For body parts, we buy our aluminum in the 3003 H0 and H14 state. 3003 means the aluminum was alloyed with manganese to make it a bit stronger than pure aluminum. H0 means its hardness is 0, or fully annealed. H14 is a little different. Each number, the 1 and the 4 mean something. The 1 means "strain hardened" (by the rolling process) and the 4 means "1/2 hard." In other words, H14 was rolled until it was 1/2 hard. H0 is really only good for a few parts, or parts with a LOT of shape as it is so soft there is not much strength left in the part when you are finished. You have to move H0 a long way to get the hardness back up. Sometimes, we start with 3003 H0 and form the part 1/2 way. Then we anneal and form it the rest of the way.

Original Cobras (and many other coach built cars) were made from 1100 alloy aluminum. 1100 is pure aluminum. It is so soft you can bend a 0.063 sheet very easily with your fingers. You can push in the center of the sheet with your finger and leave a dent It is fun to work with, but it is so weak many people use 3003 instead. In Poland we use an old Soviet alloy which has no equivalent in the US to make our bodies.

We also use 5052 H32, 6061 T-6, and 7075 T-6 to make parts. The "T" designates the aluminum was solution heat treated and aged to make it harder and stronger.

If we had wanted to stress the body, we would have probably used a much stronger alloy, like 5083 and superplastic formed the part. 5083 works really well because it doesn't have to be heat treated and it has a very high strength when it comes out of the press. Here is a video we just posted of how strong the new aerospace SPF alloys are.

David

 

Thanks guys!

Happy to share.

David

 

Very nice work! I am curious, though...is there an advantage to making the body out of bronze, or is it just because it'll be really cool?

 

Bronze is much, much harder than aluminum. Remember, bronze was used to make weapons for thousands of years after it replaced copper. Swords were invented in the bronze age (and not in the copper age) because bronze was finally strong enough to make a long blade. Copper wasn't strong enough to make swords (they did make copper axes, however, as evidenced by the "Ice Man." We advanced from the copper age to the bronze age when we figured out how to alloy copper and make bronze. (Now, there are many different kinds of bronze and I am just giving a very brief over view here of the history involved.)

Aluminum is very light and quite soft. Aluminum is 1/3 the density of copper or bronze. (Copper is slightly denser than bronze as bronze is copper alloyed with something else, usually tin). In our case, the silicon bronze we are using is about 97% copper and 3% silicon. The silicon helps it to weld and gives it a beautiful golden color.

Copper is softer than bronze, but a bit harder than aluminum. Silicon bronze has a yield strength of around 50,000 psi. The aluminum in the original AC Cobra (alloy 1100) had a yield of around 10,000 psi. So, you can see bronze is a beast to form. We had to heat the bronze up to lift it off the die then slap it back down (while hot) to get it to lay down against the die. It was a real job. But, it really made a beautiful part when we were finished.

I would say bronze is 3 to 5 times harder to form than aluminum, but 1000 times easier to weld :LOL:

David

 

I'm glad you liked it. Thanks!

David

 

Thanks for the kind words. Bronze is just beautiful. The customer already owns one of our copper cars. He wanted something different and wanted to see if a car could be done in bronze. The "advantage" is bronze is "really cool."

David

 

you gotta be shittin me, that didn`t just happen, well, the vote is in, the rest of us are hacks!!!!! awesome work!!! beautiful!!!

 

Thank you very much for the clear answer! What sort of material can you make a super plastic form from? Or to put it another way, if you doing a short run what would the easiest material to work be that you could use or the easiest economical material? Do you use super plastic aluminum for any visible body parts?

 

Beautiful work, thanks for the videos!

I was always under the impression that your body panels were made with two forms and some sort of a press. Its awesome to see that process of working the metal by hand over the form.

Is it correct to assume that you machine the dies in house? Do you know of any place that would do this sort of thing for an individual rather than a company? What is an approximate cost for machining a die with a pre-made 3d file?

 

"Hacks?" Heavens no. This site fills me with inspiration every time I come here. You are what America was founded on--everyone pursuing their own separate dreams and then working hard to make them come true. Many of the things I see here, made in guys own, humble garages, amaze me. You guys have a dream, go for it, and don't let anything stand in your way. We here at Kirkham just happen to have accumulated a lot of tools so it is easier for us to make some things.

David