All sorts really. Currently looking for replacement axles 1.5" diameter. An outfit called Wicks Aircraft have what looks ideal but they can't/won't supply any info as to material or treatment, so useless.
Bruce to answer your questions I am looking for a straight shaft (steel, prob 4130) 1.5" diameter x 9" long and 0.25" wall thickness (though would be more happy with solid). Which is press fit into yoke. Product AX1-1.5 x 12 looked ideal
Although the description says it is tube when I inquired as to the wall thickness was informed it was solid (so for a start their descriptions can't be trusted). Great! that would be ideal (I thought) But they won't provide any written conformation as to the material or treatment (I would have been happy with something as simple as normalised 4130 on the invoice) so can't really expect my engineer to just take it on trust.
the AX1 has a part number, so as far as a parts supplier goes, they don't need to supply any materials data, just confirmation by way of a Form 8130 that the supplier documentation they received says its an AX1. In fact, with product liability being what it is, they cant actually make any claim as to its technical specs other than it is an "AX1". I dont know of any supplier that would. You need to ask for the suppliers layout drawings - which may be proprietary, but should be available since if intended for non-certified aircraft, it is the installers responsibility to ensure it is fit for service. It sounds like you may have to manufacture locally if they cant supply the layout drawings.
If it was supposed to be easy. everyone would be doing it...