I have restored a kity planer and it needs a fence made for it. The original one in the diagram (missing from my machine) was a piece of bent steel, attached to a 20mm rod.
I'm reluctant to copy the original design as it looks quite flimsy, however the 20mm rod bit I will stick with as the parts for that are present on my machine. I wanted these 'square saddle washers' to form the interface for the fence assembly I will make to attach to the rod. Having briefly had a look at the cost of the washers on the internet I suspect I will end up going down the line of filing the end of the rod flat instead!!!
Am deciding whether to use solid 20mm rod (£8.99) or 3mm wall 20mm steel tube (£12). I think both will be plenty strong enough, obviously there would be some weight saving with the tube but confusingly it is more expensive...