Thanks both.
This is a sketch of the joint we'll make if we use 100 x 100 x 5mm cold formed box section, with radii indicated as per your link, Agroshield. It'd be stick welded (apparently our MIG isn't powerful enough) and it'll have to fill the gap at the vertical join (bottom and top centre in the sketch) caused by the radius of the upright. Will that work, or would the heat of building up the weld lead to distortion - we need to keep the whole thing square. If so, or if there are other reasons not to do this, are we better using 90 x 90mm for the arms that will hold the wheel and anvils, and thus butt to the 100mm upright on all four faces?
This is a sketch of the joint we'll make if we use 100 x 100 x 5mm cold formed box section, with radii indicated as per your link, Agroshield. It'd be stick welded (apparently our MIG isn't powerful enough) and it'll have to fill the gap at the vertical join (bottom and top centre in the sketch) caused by the radius of the upright. Will that work, or would the heat of building up the weld lead to distortion - we need to keep the whole thing square. If so, or if there are other reasons not to do this, are we better using 90 x 90mm for the arms that will hold the wheel and anvils, and thus butt to the 100mm upright on all four faces?