Author Topic: Cleaning compasses  (Read 2127 times)

Offline AdrianTurner

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Cleaning compasses
« on: March 05, 2009, 01:18:59 pm »
Hi all,

I'm trying to clean our club's silva sightmaster compass and clino, but can't seem to find any descriptions of how to take them apart.  Anyone had any experience doing so?

Ade

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Re: Cleaning compasses
« Reply #1 on: March 05, 2009, 02:50:00 pm »
Yes, but unfortunately not in a manner that allowed them to be reassembled and function again.

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Offline Burt

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Re: Cleaning compasses
« Reply #2 on: March 06, 2009, 02:13:14 pm »
Do it like porcupines mating - very carefully!
The wavy brass spring which holds in the bezel is a sod to get back in once escaped.
Warm water and toothbrush job, I reckon. :thumbsup:
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Offline nickwilliams

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Re: Cleaning compasses
« Reply #3 on: March 06, 2009, 04:38:41 pm »
Are they Silva, or are they actually Suuntos?

I seem to remember that Wookey and I wrote an article on how to open up and modify a set of Suuntos to make them easier to clean. I thought it was published in Compass Points but I can't find it in the archive at http://www.chaos.org.uk/survex/cp/ so it might have ended up in an issue of the CREG Journal. Or maybe I just dreamed the whole thing.

I've never had to take my Silvas apart (I have the prismatic ones which are much easier to clean) but I have taken Suuntos to pieces, and the Silvas are basically a copy so the same approach is worth considering. The basic method was originally described in an article in Canadian Caver some time in the 1980s, IIRC. The trick is to drill a small hole on the edge of the disk in the back. This allows a jeweller's screwdriver to then be used to lever the disc out. Then undo the grub screw in the end and the liquid filled module can be pushed out of the housing.

Unless you have the models which have washout ports (and, in fact, even if you have), actually getting into the optics to clean them is not easy even with the module removed, so a cheap ultrasonic bath would be a worthwhile investment.

YMMV, of course, and as far as a guarantee is concerned, you're on your own!

Nick.
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Offline AdrianTurner

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Re: Cleaning compasses
« Reply #4 on: March 06, 2009, 11:21:21 pm »
Cheers guys, might have a look at an ultrasonic bath.  I've also been in touch with Silva, who've kindly offered to clean them for me, I just need to post them to Sweden.  Will give it a try myself and send them off if they still stay mucky.