The AM Forum
December 05, 2024, 08:45:10 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Vibration Isolators  (Read 4683 times)
0 Members and 1 Guest are viewing this topic.
KD1SH
Member

Offline Offline

Posts: 883



« on: October 22, 2024, 11:08:42 AM »

  The 12v Harbor Fright winch on my tower has served me well for years, but like most 12v brush type motors spinning an array of planetary gears, it screams like a banshee. Mounted solidly to the bracket on the tower, which is in turn mounted to a bracket on the side of the house, the high frequency vibrations from the winch are transferred directly into the tower, turning the side of my house into a sounding board. I very rarely leave the tower extended when I'm not using it. My wife goes to bed earlier than I do most of the time, and after an evening on the air with the tower raised, lowering it again often wakes her in a panic, heart pounding—the noise inside the house really is horrendous—and me feeling terrible.
  I am blessed with a wonderful wife, very understanding and approving of my radio hobby; she even goes to hamfests with me, gets along great with my radio friends, and couldn't care less what I bring home from hamfests, as long as she's not tripping over it on the living room floor. So, the last time my winch rudely shattered her sleep, I told myself I wouldn't raise the tower again until I found some way to quiet it.
  Here's my solution, and it works amazingly well. The noise inside the house is reduced by probably 75%, and I can barely hear it at all from the shack. Happy wife—happy life.
These are the isolators I used:
https://www.amazon.com/dp/B009M97ISW?ref=ppx_yo2ov_dt_b_fed_asin_title
https://www.amazon.com/dp/B006GBLYIO?ref=ppx_yo2ov_dt_b_fed_asin_title
  Two steel plates, wider than the footprint of the winch to distribute the load more evenly, and of course a handful of nuts, bolts, and washers completed the installation.


* Isolators.JPG (88.24 KB, 1024x768 - viewed 148 times.)
Logged

"Gosh, Batman, I never knew there were no punctuation marks in alphabet soup!"
—Robin, in the 1960's Batman TV series.
W7TFO
WTF-OVER in 7 land Dennis
Contributing
Member
*
Offline Offline

Posts: 2496


IN A TRIODE NO ONE CAN HEAR YOUR SCREEN


WWW
« Reply #1 on: October 23, 2024, 09:16:42 AM »

Good job there.

I hear you (and them) about planetary winches, noisy beasts.

73DG
Logged

Just pacing the Farady cage...
W1ITT
Member

Offline Offline

Posts: 584


« Reply #2 on: October 23, 2024, 01:19:26 PM »

Sorbothane is wondrous stuff.  I have had insoles that were made from it and they made life working on concrete floors more tolerable.  But the material degrades over a long period of time, and I am told that there are different formulations, some of which may be susceptible to UV degradation in your application.
It's good enough that, if it got tired, I'd replace it with more of the same.
73 de Norm W1ITT
Logged
KD1SH
Member

Offline Offline

Posts: 883



« Reply #3 on: October 23, 2024, 01:25:21 PM »

  A few more technical details for anyone who might contemplate a similar project:
  Many vibration mounts, complete with threaded studs or receptacles inserted into the rubber, are available, but these are almost exclusively designed for compression loads only, rather than tension. Since the winch would be pulling downward on the cable, the resulting force on those mounts would be tension in the upward direction, working to pull the isolators apart.
  In my design, the holes in both plates are 1/2"—oversized for the 5/16" bolts that pass through them—with the smaller Sorbothane isolators, which have a minor outside diameter of 1/2", inserted into the holes, to completely isolate each bolt from any contact with the plate. The larger diameter Sorbothane isolators between the plates are under compression, as are the ones underneath the bottom plate, bearing the full upward load when the winch is pulling on the cable.
  Before I even actuated the winch for the first trial run, I could tell that it was going to work: rapping on the winch with my wrench, which normally resulted in a ringing, reverberating "clang, clang," just as if I'd rapped on the tower itself, now resulted in a dead sounding "thunk, thunk,"—no sound or vibration being coupled into the tower at all. Success!
Logged

"Gosh, Batman, I never knew there were no punctuation marks in alphabet soup!"
—Robin, in the 1960's Batman TV series.
KD1SH
Member

Offline Offline

Posts: 883



« Reply #4 on: October 23, 2024, 01:38:47 PM »

  Yes, I've already ordered more, just in case they degrade. UV probably won't be much of an issue, since the tower is on the north facing side of the house, with about a 10" eave overhang, so it's pretty much perpetual shade there, even at noon in summer. I'm wondering if extreme cold in our Northeast winters will stiffen them enough to reduce their effectiveness?
  Sorbothane is indeed nifty stuff; very soft and gummy feeling, and oddly sticky on the fingers. If my tower were heavier, I'd probably need to use a stiffer durometer material, since the compression load would probably squash these to the point where their performance would diminish. It's a light duty three-section tower; the combined weight of the two moving sections is probably less than a hundred pounds.

Sorbothane is wondrous stuff.  I have had insoles that were made from it and they made life working on concrete floors more tolerable.  But the material degrades over a long period of time, and I am told that there are different formulations, some of which may be susceptible to UV degradation in your application.
It's good enough that, if it got tired, I'd replace it with more of the same.
73 de Norm W1ITT
Logged

"Gosh, Batman, I never knew there were no punctuation marks in alphabet soup!"
—Robin, in the 1960's Batman TV series.
WBear2GCR
Member

Offline Offline

Posts: 4145


Brrrr- it's cold in the shack! Fire up the BIG RIG


WWW
« Reply #5 on: November 12, 2024, 02:38:53 PM »

A few points to consider?

The bottom nuts - use two, locked to each other, and the lower one being a self locking type.
Vibration is the enemy. Extrusion of the threads = disaster.

(edit, looks like the nuts are the locking type...)

The bolts ought to be "grade 8"...
Logged

_-_- bear WB2GCR                   http://www.bearlabs.com
KD1SH
Member

Offline Offline

Posts: 883



« Reply #6 on: November 12, 2024, 04:24:43 PM »

Yes indeed, the nuts are "nyloc" types.

A few points to consider?

The bottom nuts - use two, locked to each other, and the lower one being a self locking type.
Vibration is the enemy. Extrusion of the threads = disaster.

(edit, looks like the nuts are the locking type...)

The bolts ought to be "grade 8"...
Logged

"Gosh, Batman, I never knew there were no punctuation marks in alphabet soup!"
—Robin, in the 1960's Batman TV series.
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.049 seconds with 19 queries.