Bending Machines

Building a bending machine was a decision we came to after modelling the boat in 3D, during this process we came to the conlusion that without a bending machine the stringers would be very hard to install directly without distorting the frames. It was a very interesting design since it is 100% original, we were simply not happy with the designs we saw other people using. After throwing around ideas for 2 months we sat down at a whiteboard and designed the entire thing in around 5 hours.

The machine is designed around the fact that we chose to use bearings from an automobile wheelhub, this is the cheepest source of bearings that can withstand this kind of load. There are two 400x400 mm (16" x 16") plates, these are placed so that there is a fixed slot between. These plates are drilled and threaded to accept 12mm bolts in a grid. Each wheelhub is fixed to a 20mm (0.8") adapter platter which is drilled to fit the grid on the plates.

A sled is run in the slot between the plates, this sled is moved by a threaded bar and secured by a clamping bolt from below. Finally the third wheelhub is bolted to the top of the sled which is in itself an adapter plate.

When designing the rollers themselves we had to consider the exteme load, to avoid the rollers being deformed we chose a a high strengh steel sold under the brand Hardox®, the type we went for has a Brinell hardness exceeding 400 while mild steel is normally around 100. Because of this machinability is poor to say the least, we went through 4 TiN coated drillbits while drilling 36 holes! While we did not have the lathe at this time I doubt we would have subjected it to this form of torture, instead we used the plasma cutter to "rough cut". We mounted the rough cut on the wheelhub, created an attachment for an angle grinder and spent a couple of hours grinding the discs to a very tight tolerance. To finish we sacrificed a 1/2" socket by welding it to the top of the center roller, this enables one to roll/turn the work through.