Bending Rolls

By Brian Simpson

The problem with being a Model Wheelwright is that you have to make wheels! This entails making tyres, strakes and nave bonds. I found bending round tins a bit of a problem so I decided to try to make a simple set of bending rolls to do the job. The rolls are the pyramid type.

Each side consists of two hardwood strips 51/4 inches x 7/8 inches x 13/16 inches glued and nailed between two 6 inches x 3 inches x 3/16 inches plywood sheets. The strips are set so that there is a 5/8 inch gap between them but the plywood sides have a slot cut in only 3/8 inch wide x 31/2 inches long making a square channel in which a hardwood bush, which carries the top roller spindle, can slide. (See Top View of One Side on plan and Photos)

Two holes are bored 3/8 inch diameter centred 13/4 inches apart 33/4 inches down from the top to take the spindles of the two bottom rollers. The best way to make sure that all are aligned is to sandwich the sides together before assembly to the base and drill and cut the slot and holes through both at the same time. The base is a piece of ply 3/4 inch x 6 inches x 3 inches.

The bushes (you need two) are made from hardwood each 1 inch x 7/8 inch x 5/8inch with a 3/8 inch hole bored through them centrally.

The rollers are made from 30mm mild steel tube each 31/4 inches long with wooden dowels glued inside with epoxy resin. These wooden dowel inserts need to be drilled out centrally at 3/8 inch diameter to take the spindles which are glued in. The spindles are made from 3/8 inch mild steel rod. The spindles for the two bottom rollers are 61/4 inches long but the top spindle is 81/2 inches long.
The mechanism by which the top roller is adjusted is made from two lengths of 3/4 inch angle iron. It is drilled and tapped to take a 10mm threaded rod and then screwed to the side panels 11/4 inches down from the top. The adjusters are made from 10mm studding with wooden handles drilled and glued to the top.

One problem I did find is that the adjusters tend to waggle a bit because the angle iron is thin and therefore there are not many threads in the hole to support the threaded bar. One solution would be to silver solder a 10mm nut to the angle iron.

To assemble:
Screw one end to the base. Put the spindles of the two lower rollers into the holes then fit the other end onto the spindles and screw it to the base. Screw one end of each adjusting mechanism to each side but leave the other screw out and pull them to stand vertically. Now slide the wooden bushes onto the top roller spindles and slide the bushes into the channels in each side. The roller will drop down to rest on the bottom rolls. Position the adjusting mechanism horizontally and insert the other screws to fix them in position. Your rolls are finished. Cost-about £10.

To page 2 "using the bending rolls"