Best sheet metal for body fabrication

[alsfarms]

What is the best type of sheet metal for fabricating body panels, hot rolled or cold rolled? I assume that cold rolled is stronger and potentially harder to form but may be less prone for stress cracking? What is the determination, regarding these two materials, from those who build panels and are reading here?

Al

[Bhigdog]

Hot rolled usually has surface scale and not as smooth of a surface. The scale is very hard, abrasive, and hard to remove..justsayin......bob

[Andy J]

I get cut-offs and scraps of 18 gauge sheet steel from a small steel company where I live. It comes in 4'X10' sheets,but I've never needed that much. I assume it is cold rolled because it is very smooth.It works very well for the floor pans and patches I use it for.

[viv w]

If you are making new panels, such as door or side panels that have a slightly raised/curved shape then try getting old roof panels from a salvage yard, they will already have the slight "dome" needed without having to roll them in an english wheel.

 

[Gary_Ash]

So, Al, what parts are you trying to make?  How big?  How complicated?  How many?

[Rusty_OToole]

Auto parts stores sell aluminum killed sheet metal for the purpose, it has a rust proof coating but can easily be welded.

[alsfarms]

This project consists of two flat top front fenders to be used on my 1913 American-LaFrance fire truck. These fenders will be heavier gauge material than typical automobile body panels. I will see if I can find a few pictures and post. These two pictures show the early series American-LaFrance flat top fenders. The fenders are flat with a reinforcement oval molding riveted to the top perimiter of the fender to stiffen the fender. That's it.

Al

Edited March 10 by alsfarms
clarity (see edit history)

[alsfarms]

Here are a couple more close up pictures of a restored truck with the correct fender type for my rig. This is the fender I plan to duplicate. The black molding is formed and riveted to the fender around the full perimeter. I have a pipe jig to form the arc. Then it will be time to form the oval flat bottom molding and rivet in place. I think maybe 1/16" cold rolled.

Al

Edited March 10 by alsfarms
Clarity (see edit history)

[BlueDevil]

Cold rolled. You will have a hard time finding hot rolled thinner than .075. CR has more uniform gauge and physical properties and has a smoother surface.

[alsfarms]

Thanks

 

[Bhigdog]

Somehow I think you are located in PA. If so Bloomsburg Metal in Wilkes Barre carries sheet steel both hot and cold rolled from 10 to 26 gauge. The hot rolled is pickled and oiled to remove the scale. They sell in small lots ( single 4 X 8 ) for PU at facility. Looking at your fenders I'd think something like 14 gauge. Just sayin..........Bob

[Frank DuVal]

On 3/9/2024 at 5:18 PM, Rusty_OToole said:

Auto parts stores sell aluminum killed sheet metal for the purpose, it has a rust proof coating but can easily be welded.

You must be up north. I have never seen sheet metal for sale in auto parts stores, much less specifically aluminum killed sheets. I used to buy 4 x 10 sheets from the HVAC suppliers. They also had non galvanized. 

[Rusty_OToole]

1 hour ago, Frank DuVal said:

You must be up north. I have never seen sheet metal for sale in auto parts stores, much less specifically aluminum killed sheets. I used to buy 4 x 10 sheets from the HVAC suppliers. They also had non galvanized. 

Way up north. Don't body shops do metal work in the US?

[jdome]

48 minutes ago, Rusty_OToole said:

Way up north. Don't body shops do metal work in the US?

Simple answer is no. They replace fenders and panels.

[TTR]

14 minutes ago, jdome said:

Simple answer is no. They replace fenders and panels.

... and if replacement panels aren't available, they consider use of slide-hammer pullers and copious amounts of filler "metal work". 

[Gary_Ash]

@alsfarms  From the photos you show, the fenders will be about 14" wide and 5 ft long.  16 gauge steel (1/16" thick) weighs 2.5 lb/square ft, so each one will weigh about 15 lbs.  The U channels for the edges can be bought as "U edging", available to slip on 16 gauge metal, though they seem to be available only in 1" width and have flat sides.  A steel shop could water jet or laser cut them down to the ~1/2-inch width in the photos.  The steel shop could also cut the 16 gauge pieces for the fenders and put them in a slip roll to make smooth bends, easy if you give them a template of the curve.  Since it's hard to get the slip roll curve in exactly the right position, start with a 6 ft or 7 ft length, and trim after forming. 

 

Bending the corners in the U channels will be difficult without kinking them.  Maybe you can make a jig from 16 gauge steel with a 2" radius, press the channel on the jig, and heat the channel red hot to bend it around the corner.  It's going to want to pucker on the inside of the curve.  I think I'd make the four (good) corners, then weld on straight lengths to make the full border.  Good luck!

 

From Metals Depot web site

[Gary_Ash]

@alsfarms When you get tired of trying to bend the U channel around a corner and it keeps buckling, maybe make corners from cut pieces and TIG weld them together, grind the U to shape.

 

 

[demco32]

We use these machines