The larger mangles had square bars. I repaired one for earlswood museum only last year this had a square bar through it with metal washers on the ends. The bar was not very straight so the sq. hole needed some play to enable me to get the bar through. I was lucky this was only going to be for display so I jointed two grooved blocks together giving me a square hole. The originals were in a solid piece a much more difficult proposition.