Building a Ring Roller

First of all, what is a ring roller? It is a device with 3 rollers. You roll a strip of metal between the rollers, and it curves the metal:

Ring Roller in Action

My design works by using wrenches to turn the bolts. In practice, it worked fine to turn only the bolt on the "middle" (rightmost) roller.

Why build one and not just buy one? Harbor freight sells a small ring roller for about $50. It was too small for the jobs I wanted. The next size up I could find was about $800. My ring roller cost about $50 of materials. Also, the ring roller was a great project for a beginner like me to practice my metal cutting, machining, and welding skills.

Being a beginner, I bought a large steel plate and cut my pieces from it. From this I learned it is much easier to buy metal as close to the finish size as you can! If I were to do another ring roller I would buy 1/4 inch by 6 inch wide pieces, and design it to use the 6 inch wide pieces. Also, I am a beginning welder, so don't assume I mean for the pictured welds to be Space Shuttle quality!

The main plates:

Side PlateSide PlateBottom Plate

Left Picture: The long middle slot allows the center roller to move up and down. The two holes below it are for the side axles. The bottom 2 holes were just to affix the plate to the mill to machine the slot and holes. 2 of these plates were made.

Middle picture: Another side plate. The half circles in the ends allow the ring roller to be bolted to a table top. 2 of these plates were made.

Right picture: The bottom plate. The big hole in the bottom is for the main bolt, and the half circles to allow the ring roller to be bolted to a table top. 1 of these plates were made.

These plates were welded together into a box:

Main boxBottom bracingBottom brace with bolt

I added a box structure to the bottom for strength. I figured if I was going to bend 1/4 inch thick steel, I needed something stronger than a 1/4 inch thick plate on the bottom. The last picture shows how the bolt goes. Turning the main bolt more will bend the metal more.

The next job was to make a structure that would hold the middle roller, and allow it to be pulled down with alot of force by the main bolt. The pieces were 1/4 by 1.5 inch mild steel. I made a box structure for greater strength, and to keep the main nut from spinning. The holes are for the axle bolts of the middle roller. I found that the arc on my TIG welder would go sideways into the corners, so I gave up on welding the beads all the way to the inside corners. Safety warning: Many nuts have a coating that can be toxic if welded, so I ground off the coating before welding the nut.

Middle Roller HolderCenter Roller Holder

Here is the assembled product. I found it easier to just C-clamp it to the work bench rather than bolt it down. The rollers are 1.5 inch cold rolled steel. I drilled and tapped 1/2 inch holes in each end. A smaller piece of bolt at the bottom of each hole keeps the 1/2 inch bolt from bottoming and adjusts how far it goes in. The bolts just spin in the plain metal. I greased the bolts, and it works great without fancy bearings.

I had to remake the rollers. The first time I used a small lathe. It was not strong enough, and flexed enough that the rollers spun off center. I remade them on a friend's larger lathe, and they now work great.

To use it, just insert the piece of metal, tighten the main bolt a bit (I've been doing about 1/4 turn at a time), and spin the rollers via their bolts. Generally you'd do a curve with several passes. The picture below shows it curving 1/4 x 3 inch steel. To my pleasant surprise, it does not take much strength to bend metal this thick.

Assembled Ring RollerRing Roller in Action

The nature of a ring roller is the last inch or so of the metal does not get bent and stays flat. You have to either live with that, or cut the flat part off. Here is an example of a hoop I rolled. If you look closely, you can see the last inch is still flat.

Hoop Rolled from FlatFlat Ends

Advantages of my design:
 Disadvantages: