hi redshift... ye interesting read, im not bothered by the sand as i make my own pins and barrels for the mip's- bit of silver steel then harden with a mapp gas torch and water. just have to strip and clean shafts after the run.

nice attempt at sum shafts tho, i made mine from 316 stainless, easy to machine and no rust . i made mine 1mm thicker at the shafts thinnest point so they are a smidge stronger and seem to resist bending better, putting a set on the back will be the real test as i still have my 5 years old mip's on the rear but the centre rear is stainless, i extended my truck by 40mm and had to make a shaft that fitted

gears can be cut on the lathe using a rotaytable (must have indexing plates too), but for you it would have to be a careful choice under the centre height of your machine then the table would have to be raised to correct centre height

ha ha that shaft is well bent in your photo, i thought i bent mine badly, problem i get is as the mip's are quite strong/brittle they tend to start splitting along there length in a helix type crack after i bend em straight a few times, i have not had this so far with the stainless ones and have straightened them a few times each, so far and all good.
see ya all...