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Re: [TowerTalk] Metal Thermal Rate of Expansion

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Metal Thermal Rate of Expansion
From: Gedas <w8bya@mchsi.com>
Date: Sun, 3 Oct 2021 17:59:20 -0400
List-post: <mailto:towertalk@contesting.com>
Thank you grant. I was not sure how to interpret that linear expansion as my situation is using round tubing. Not sure if the diameter would change at the same rate as in a linear strip of metal. 73

Gedas, W8BYA EN70JT

Gallery at http://w8bya.com (under repair)
Light travels faster than sound....
This is why some people appear bright until you hear them speak.

On 10/3/2021 5:19 PM, Grant Saviers wrote:
The materials difference in thermal expansion is 1.7e-6 per degree C.

So 2" x 1.7e-6 x 100d C temperature range = 0.00034"

You will never notice at any place on earth.

Grant KZ1W

On 10/3/2021 11:45, Gedas wrote:
It is has been WAY too many decades since my last ME classes to be confident in my estimations so I am wondering if someone can give me their opinion if I am going to run into trouble.

The YT video (URL below) shows a new 10 GHz elevation mount I am making. For a bearing I chose to use 6061-T6, ~2" OD tubing rotating inside a 2" ID brass collar. I had to turn down the aluminum tubing a bit to fit nicely inside the brass collar which now allows it to turn freely w/o slop but this is at room temperature.

My fear is that on a very cold day or a very hot day my home made bearing may seize up on me.

Can someone run a quick calculation? I see that my aluminum and brass have 13.0 and 11.3 (for yellow brass which is a WAG for what I have). I am leaving off the units and exponents etc.

https://www.engineeringtoolbox.com/thermal-expansion-metals-d_859.html

Here is the URL that shows the homemade bearing:

https://www.youtube.com/watch?v=Ps_PRXaByz4


Gedas, W8BYA EN70JT

Gallery at http://w8bya.com (under repair)
Light travels faster than sound....
This is why some people appear bright until you hear them speak.


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