[TowerTalk] HAM IV rotor / mast slipping

[Pete Smith N4ZR]

K7NV makes the same observation on his web page, Dick, and suggests that 
if you want to pin a mast the hole needs to be drilled very precisely 
and a pin specifically designed for this purpose be used, rather than a 
bolt.

73, Pete N4ZR
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On 4/5/2012 2:21 PM, Dick Dievendorff wrote:
> Someone suggested to me that I might increase the mast to clamp friction by
> wrapping the mast with something with a little bite.  Do they make
> double-sided emery paper that can tolerate being wet?
>
> I have a clamp to mast size mismatch that I'm going to try to correct with
> shims, and I might end up pinning too.  My prop pitch doesn't have a wedge
> to break.
>
> I've used pins (usually grade 8 bolts) in the past and they have failed
> because they weren't hefty enough. The hole ended up larger than the pinning
> bolt and the wind would work it back and forth enough that it eventually
> fatigued and failed.  The hole got larger in this process.
>
> I think I had too much on the mast.  I've changed that in my new
> installation.
>
> Dick, K6KR
>
>
> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of Frank
> Sent: Thursday, April 05, 2012 5:24 AM
> To: n8de at thepoint.net
> Cc: KA9S - Jeff; towertalk at contesting.com
> Subject: Re: [TowerTalk] HAM IV rotor / mast slipping
>
> n8de at thepoint.net wrote:
>
>> The Tailtwister (big brother of the Ham IV) has a pre-drilled hole
>> through the upper rotor housing and clamp piece.
>>
>> I'd pin the mast with your rotor, just as is done with the T2X.
>>
>> 73
>> Don
>> N8DE
>>
>>
> Pinning the mast to the rotator is a sure way of preventing mast slippage.
> It also puts you at risk for rotor destruction if the wind load becomes
> overly excessive.  Since there is no good way of predicting how strong the
> wind is going to be here in Texas,  I have preferred not to pin the mast to
> the rotor (anymore).
>
> It is a PIA to have to re-align the directional calibration every so often,
> but it is an even bigger PIA to replace the rotor after its gears get
> striped.
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