model heli main shaft clamp

[Bill Reed]

At the minute I am messing with a small rc heli. The rotor head is held on by a 2mm bolt going across the drilled main shaft,so the head will never pull off.

the head then as two 1.6mm bolts going through the head straddling a typical slot for clamping.

Both sides of this head ,either side of slot are threaded, so as soon as the bolt head touches the face,it can not pull the rear in to clamp.

This as got me thinking, will that ever work???? I would of thought the front should be a clearance hole?

if the 2 threaded hole system can/does work would love to know. in this case because the bolt is only 1.6mm it will snap for sure.

thinking of opening the front hole BUT not my heli,building for someone

[Peter Christy]

Some pictures would help here, and also, how small is "small"?

Clamp fittings can be amazingly secure. I'm currently using a clamp shaft adapter to connect a (powerful) electric motor to the gearbox of a large vintage helicopter. So far, so good!

Said vintage heli also has the rotor head secured by a single 3mm allen bolt passing through the head and shaft. The fuselage is 6ft long with a rotor that overhangs that, so it is not small! Neither is it light, but the head speed is very low by modern standards.

It was designed by a highly qualified engineer nearly fifty years ago, and has stood the test of time, so don't be too surprised by the apparent flimsiness of the attachment method. (And you should see some full-size ones!!!)

Just be careful not to over-tighten the small screws! Its very easy to damage the heads, making it difficult to remove them for maintenance / repairs! The clamping action does not require too much tension on the screw to achieve a secure fixing, especially on small and light models.

Cheers,

--

Pete

[Bill Reed]

Thanks Peter will post picture later.