Re: Aluminium and Titanium parts.
The ultimate test is the bench grinder.
While you obviously wouldn't use it on good parts, the test can be vital for things like fasteners and axles where the material is unknown. Failure can be catastrophic.
Ti aircraft fasteners must carry a certification number, but Ti fasteners for other uses do not have to be marked. While titanium usually appears as dull grey, anodised aluminium look-alike products can exhibit the same colour. The latter could also be hard-anodised, so a quick file test is not always conclusive.
Titanium readily generates a pure white spark on the grinder, aluminium does not readily spark and steel produces a yellow spark.
Has anyone trialed the 7000-series hard-anodised hollow axles? They are incredibly light; a bit scary though.
David Fryer, Brisbane, Australia