From: "Marvin Kaye" <marv@lancaironline.net>
Subject: Re: [LML] Re: Outboard elevator hinge bleeding
To: lml
Date: Mon, 19 Feb 2007 22:24:25 -0500
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Posted for "James H. Keyworth" <jhk@clearwire.net>:

  I seem to recall that Chris Zavatson posted a very detailed process for
eliminating hinge looseness (and thus excess wear) a year or so ago.
  
  JHK

[Rather than pointing everyone at a link I'm sure Chris wouldn't mind if I 
simply copied his post here...  good info is always worth multiple passes. 
 Thanks to Chris for his frequent contributions here.  <M>   ]


"""This topic has had a fairly short cycle time on the LML, re-emerging 
relatively often. I follow these threads with interest since I tinkered with 
the hinge issue a couple of years ago. The result is an all metal solution 
that eliminates play far better than anything I have seen thus far. Wear has 
not been measurable yet, but I only have a few years and couple hundred hours 
on the parts. The details are online at: 
http://www.n91cz.com/HingePlay/hinges.htm
In short, a standard MS hinge is reamed (hand reamer from McMaster) and then a 
larger diameter pin is used (SS welding rod).

General conclusions:

1.The standard MS hinge extrusion has a huge allowable tolerance for the hole 
diameter (.005"). Without modification, there is no single pin or insert that 
will both fit all hinges and not have play.
http://www.n91cz.com/HingePlay/hinge_spec_1.jpg
http://www.n91cz.com/HingePlay/hinge_spec_2.jpg

2.The MS pin is undersized which adds to the tolerance in 1.
http://www.n91cz.com/HingePlay/pin_spec.jpg

2.Wear can be controlled by contolling the pin/hinge tolerance and clearance.

3.Plastics such as Teflon and Nylon are very soft and will flow and deform if 
subjected to high loads.
http://www.n91cz.com/HingePlay/sleeve-web.JPG


How much play is acceptable is very difficult to quantitfy. Certainly less is 
better, in particular for non-mass balanced surfaces such as large trim tabs.
The following video clip compares the play of various hinge options.
http://www.n91cz.com/HingePlay/Hinge_Play_Test-low_res.WMV

Chris Zavatson
N91CZ
360std
www.N91CZ.com
"""