MicroNavigation Forum

Techniques => New Techniques & Learning => Topic started by: Brian on October 23, 2011, 08:48:36 PM

Title: Loose compass hinge
Post by: Brian on October 23, 2011, 08:48:36 PM
Those who use Type 15 compasses might have noticed that over time, the hinge mechanism can become annoyingly loose, the result can be difficulty in maintaining the mirror in a stable sighting position (of ~ 45 degrees). 

When this happened to my wife's old Silva Ranger, we retired it.

But at a recent conference (SARCON), one of the speakers suggested a remedy.  Just use a little non-permanent (blue tube) Loktite.

With the lid closed, I put a tiny drop on each of the hinge interfaces and opened and closed the lid for a few minutes to make sure the stuff spread within.  After that, I wiped off the excess Loktite and put the compass down for a half hour or so.  Then I worked it (opened and closed it) a couple of times, and finally went about my business for awhile.

Now - over an hour later, the mechanism is as smooth and tight as new, or even more so. 

Don't know what the fix's longevity will be, but it sure is nice for the time being! 
Title: Re: Loose compass hinge
Post by: Brian on October 26, 2011, 11:31:11 PM
Could have done with this knowledge a couple of years ago when for a trip to the Andes we bought new Type 15's and threw away the old ones with the dodgy hinges :(

Good posting Brian.

Thanks!  Nice of you to say.

Does anyone know how the bubbles arise in the compass capsule? My Expedition 54 works fine with them, yet they are annoying.

Well, bubbles may form when the integrity of the capsule is compromised (as in microcracks are present) for obvious reasons.

But they also form in some compasses if the temperature decreases significantly or the the atmospheric pressure decreases significantly (as in the compass goes to a higher altitude).  The thing I don't know is if, when such bubbles form, the capsule is fully intact or not.

What I've read implies that the capsule is not compromised, but if that is the case, I don't know what the actual mechanism is (can decreased temperature or decreased atmospheric pressure somehow release gas otherwise stored in the fluid??).

I'm betting that there will always be an otherwise asymptomatic defect in the capsule or its seal for bubbles to form (if any compasses from of the same make and model do not form bubbles under similar conditions, that would argue in favor of those having bubbles suffering from some sort of capsular defect, those without bubbles having been manufactured without a defect.)

Just guessing here, folks!