Strong Shaft Design Concept

Printed shafts that have to endure shear/torsion is problematic. Printing a shaft in vertical orientation creates and smooth cylindrical face with a tight tolerance but the layer orientation makes it particularly vulnerable to the type of force you would want to apply to a pin or drive shaft. Alternatively printing horizontally makes it strong but you end up losing the smooth cylindrical face which sucks if you're trying to maintain a tight with a bearing race. I want to share a simple design method I have been using to overcome this issue. The shaft is printed in 2 pieces. The core shape is a polygon that can be printed horizontally for strength. The exterior sleeve is cylindrical and printed vertically for smoothness and accuracy. The pictures should be self explanatory. If you use it as a drive shaft just be sure the torque is applied to the core only. I've included a clamp to pinch the sleeve to the core but it is not needed for most applications. This is just about putting