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Re: [TowerTalk] Tower mast..

To: "K8RI on TowerTalk" <>,<>
Subject: Re: [TowerTalk] Tower mast..
From: Jim Lux <>
Date: Tue, 19 Sep 2006 11:21:45 -0700
List-post: <>
At 09:40 AM 9/19/2006, K8RI on TowerTalk wrote:

>----- Original Message -----
>From: "Jim Lux" <>
>To: "JC Smith" <>; "'Merlin-7 KI4ILB'"
><>; <>
>Sent: Monday, September 18, 2006 11:47 PM
>Subject: Re: [TowerTalk] Tower mast..
> > At 05:15 PM 9/18/2006, JC Smith wrote:
> >>Hi Joe,
> >>
> >>If you really want to run a mast all the way to the bottom of the tower
> >>I'd
> >>go find a used thrust bearing (the kind that's designed to support both
> >>axial and radial loads) at the junkyard for it to set on and use a rotor
> >>shelf, which you can use later when you get a real rotor, to secure it to
> >>the bottom of the tower.  That steel ball sounds a little hokey to me.
> >>You'll need to design some sort of decent brake to keep it from wrapping
> >>up
> >>your coax.  Why not just buy a decent rotor?  Can't add too much to the
> >>cost
> >>of the project when you figure in all that extended mast stuff.
> >
> > Old car rear axle and differential takes a pretty good thrust load.
>You can go to NAPA and purchase new 32009X wheel bearings for about $32.
>These appear to be widely used and a pair are actually used in the PST-61.
>No wonder it's rated to hold over 2600# <:-))
> > Welding to the brake drum is a bit of a challenge, but usually, you
> > can modify a pipe flange or similar by drilling it for the lug nut
> > pattern.
>And as we were talking earlier...that old axel is splined on one end.

Yes, but you'd better not be depending on it to slide very far in and 
out, especially under load.

One thing about working the special effects business, I got to see 
just about every lashup improvised mechanical thing you can think of, 
but I also got to see all the bizarre failure modes too. (did you 
know that turning a rear axle on end (i.e. axles vertical, prop shaft 
horizontal) only works in one orientation, at least for the one we 
used to drive a helicopter rotor.. I can't remember if it was left 
wheel up or right wheel up, but the "wrong" way ran into some serious 
lubrication issues.


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