[John Robertson Posts: 5203 Status: Offline WWW]

But armed with my trusty ball-bearing, for a particular balde pitch there is only one correct slot on the blade root. But the hub has 4 possible identations into which the ball can go - why is this?
 
I have concluded that only one of the identations in the hub makes any sense for a given blade pitch as other combinations look wrong. But why does the hub not only have one indentation?

There should be the same number of slots in the hub as there are in the blade. The angles are too close together (only 2.5 degrees in some cases) to be able to use the same slot in the hub for all of them.

[John Robertson Posts: 5203 Status: Offline WWW]

The blades that I am using are Hascom and I am wondering how to measure their pitch when I have them in the hub. The root of the blades have ball-bearing size inserts and the hub seems to have a vertical line on the root socket. Is the pitch (eg 45 degrees) measured relative to this line? Also, is the leading edge of the blade the 'fatter' edge of the aerofoil?
 

The hascon blades have the pitch marked on the blade hubs (it's moulded into the plastic next to each ball slot - a rub with something mucky and a magnifier helps .  Just count the slots in the hub and blade (for example, 3rd slot in hub aligned with 3rd slot in blade sets the pitch to whatever it says on the blade).  I assume you didn't throw out the plastic bag with the ball bearings in it ?


Yes, the leading edge is thicker than the trailing edge.