What if the set screw is harder than the shaft?
The set screw need only be slightly harder than the shaft for to make a good impingement on the shaft and therefore deliver its full holding power. However, if the set screw is softer or only as hard as the shaft the holding power will be reduced. One can easily test to see if the set screw is harder than the shaft. Simply tighten the set-screw onto the shaft and then remove and examine the rim around the cup point. If the set-screw is harder, the rim itself will retain its sharp profile. If the set screw is softer or only as hard as the shaft, the rim will be flattened indicating no impingement and, therefore, reduced holding power.
