Creating Rounded Corners

C

Calandrod

Registered
Registered
Joined
Oct 7, 2022
Messages
65
I am just getting into sheet metal work. I did a lot of restoration work on a couple little pedal cars but I am ready to tackle something bigger. I want to create a 1950's style cabinet (the ones that have the rounded corners like this service merchandiser station pictured). I think I'll start with some normal chemical cabinets and then modify it to have rounded corners and add chrome badging and all that.
What is the best way to create that rounded corner?
Screen Shot 2022-11-23 at 11.20.08 AM.png
 
The only part of that shape that is a compound curve is the corner itself. The rest of the radiused areas are just bends. The corner is a triangular section of a sphere that can be made as a separate part and welded in place.

What kind of tools do you have available and do you have welding skills? I assume the material you will be using is soft steel so there are several possibilities to create this shape with hand tools.
 
I think a 50t. press would do the job. ;)

Seriously, compound curves are a b***ch to fabricate. Especially if you wanted uniformity for all four corners. One way would be to bend the vertical sides and cut and bend the pieces to form the top curves. Making a die to fit the inside will help to ensure uniformity. From there, you can rig weld the seams and finish by grinding. You might also consider making a separate solid piece to create the complex curves. It would be more manageable to sculpt into your final shape. You could use an existing shape to create a mold and fill with epoxy resin to create the piece. Lacking an existing shape for a pattern, you could carve one out of plaster of Paris. There are various flexible materials used for making reusable molds. Look for some of the arts and crafts videos on You Tube.
 
Sharpe Corp. sells half spheres. We used to cut wedges out of them for spherical corners. Tack them on a plate for handling.

You can also cut a funny shape into the flat and happen to shape, then weld. Tricky!

Sent from my SM-G715A using Tapatalk
 
Weldingrod1 said:
Sharpe Corp. sells half spheres. We used to cut wedges out of them for spherical corners. Tack them on a plate for handling.
Click to expand...
Very cool, do you have a link? My Google fu didn’t turn up anything.
 
If you are looking for a great primer on doing great sheetmetal work cheaply it’s pretty much impossible to beat Ron Covel.
 
I would first create a mold to form sheet metal on, just for the four corners, then tack weld them to the body , then gradually fill inbetween the welds , then grind. a mushroom shape metal fabrication dolly would be handy to have, another option is the old fashion way of using a sandbag and tear shape hammer or a pneumatic planishing hammer to form the bowl shaped corners, , thin 22Ga sheet metal should form very nicely .
 
I looked at those spheres mentioned in post #4. They are available in thick enough wall material to serve as dollies. You could rough out the shape and planish the part using a shop-made wooden slapper covered in leather or even just a bare wood 'hammer' of some kind. I think the spheres are too thick to be used directly for your purposes.
 
Last edited:
Ken from ontario said:
I would first create a mold to form sheet metal on, just for the four corners, then tack weld them to the body , then gradually fill inbetween the welds , then grind. a mushroom shape metal fabrication dolly would be handy to have, another option is the old fashion way of using a sandbag and tear shape hammer or a pneumatic planishing hammer to form the bowl shaped corners, , thin 22Ga sheet metal should form very nicely .
Click to expand...

I made a female doming die out of PVC for my 12" CP pneumatic planishing hammer. Works great for aluminum parts and would probably work on thin mild steel parts too. The male side can be anything with a rounded shape and I have a number of those available to me.
 
You must log in or register to reply here.
Back
Top