Stainless steel 25mm shaft with 5mm keyway slot, associated bearings and spacers. The shaft was engineered to accommodate cir-clips inside the bearing diameters and maintain the clutch outer position.
The simplification of having a straight shaft was an afterthought having discarded the original shaft we machined which accommodated larger diameter bearings for the free-wheeling toothed belt sprocket. The spaces were machined to allow a precision clutch spacing of .75mm. The maximum working gap with this particular gap is recommended to be 1.5mm however the supplier suggested we close the gap to accommodate longer term wear before adjustment is necessary.
The material of the spacer in this case is irrelevant, we chose a very hard wearing plastic that is usually used to make bushes. In our original design we used cir-clips, but as we made new shafts we simply decided to use spacers instead due to the ease of assembly and potential field adjustment which may need to occur away from a machine shop.
Our shafts are 10 inches long, designed however the overall working length that matters is just 8 inches.