In a message dated 97-12-30 20:02:24 EST, kg5u@hal-pc.org writes:
> While it was clamped in the rotor mast clamp, the mast looked very much like
> it was hard against one side of the Rohn 25G pointy top sleeve. When I had
> spun the mast I did not notice any wobble in the lower end of the mast.
> Aside from various stuff that might have built up in the sleeve I can only
think that > the misalignment was enough to
> cause the rotor to not be able to rotate through that spot. It seems
> incredible though.....
>
> I'm going to take another look at the mast --- maybe take it off the tower
> and check it's true--maybe it's bent.
>
> If it's straight, I can only think to use the shims referenced in the CDE
> rotor manual. What type of material is suitable as shim material? My
> understanding of what I read in the manual is that the shimstock should be
> wrapped around the mast to keep the mast centered in the rotor clamp. Will
> Aluminum sheet metal work?
>
Hi, Dale --
It's worth checking out. It is important to use a 2.0 inch OD mast when
using a thrust bearing, otherwise the mast will turn eccentrically and bind in
the TB. With a tapered top, I'd just let the mast slop around up there. As
long as it's not binding, it should be okay. Even if the mast is a little
undersized, it should still turn without binding in the mast tube. Most of the
tapered mast tubes are 2.25 inch ID so you should have plenty of clearance.
I've rarely seen a good mast shim job. You might get the mast shim
tightened down and have the mast spin in the shim. I'd spend some time
checking out the rotator/mast alignment and only shim it as a last resort.
73, Steve K7LXC
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