Tips on sealing Suunto survey instruments

[footleg]

Anyone got any tips on the best way to seal Suunto surveying instruments to keep water out of them underground? I've been told to use silicone sealant, but what is the best way to apply it, and what are the main pitfalls to watch out for?

 

[nickwilliams]

In my experience, it's not possible to make Suunto's completely waterproof, and it's actually better not to try since then it's easier to dry them out when they do get wet.

Nick.

 

[Peter Burgess]

I've not had a problem with water getting in, but have had one with the internal fluid changing colour to a very pretty shade of blue (or maybe its the plastic that changed colour - it's nigh on impossible to tell). Anyway, now it's like this, the compass and clino are virtually impossible to read. They are, it has to be said, some 20 years old. The only answer was to buy new ones. The question remains, however, why did they go blue in the first place? Cos if we knew, we could mitigate against it happening again.

 

[SamT]

I've dropped ours to bits before - you'll get a much better understanding of how the whole things works if you do this. If the whole thing is clean and dry when you assemble it - in theory you shouldnt get water in them (put em in a pelicase/aquapac/darren drum to carry) in the first place.

search for suunto on the forum as there has been much discussion in the past.

I'll dig out some photos I took at the time

 

[graham]

The most important thing to bear in mind in caring for Suuntos is not to lend them to anyone flying abroad as they will come back with bubbles in them after going through a couple of depressure/pressure cycles.

Anyone know how to get the bloody bubbles to vanish? 

 

[Peter Burgess]

One of our older cheaper Suunto compasses got a bubble in it, but it didn't seem to have a significant effect on the level of accuracy we were achieving. Perhaps the bubble wasn't big enough to have a noticeable effect.

 

[SamT]

Heres some piccies of the one I dropped to bits

you remove the grub screw (hidden under the red paint) first.

then the tricky bit is POPPING the sealed capsule out of the metal housing. You can either try and get the back plate off - but this involves a bit of gouging around.
I ended up using a g clamp - some foam carrymat, and some bits of wood - so I could force it though from the front by turning the G clamp (if you know what I mean). Was a bit nerve wracking - but worked OK.

The copper thing seems to be a spring which keeps the capsule tight up against the rubber o ring.

The problem seems to be moisture getting into the void between the capsule and the lense on the front.

Must dash - babys screaming downstairs - as is mum 

 

[ian mckenzie]

then the tricky bit is POPPING the sealed capsule out of the metal housing. You can either try and get the back plate off - but this involves a bit of gouging around.

Back when I used to try to repair these, I'd drill a small hole thru the aluminum housing adjacent to one of the hidden slots (once you've popped one, you know where they are) then pry under it with a micro-screwdriver. Then filled the hole with epoxy once reassembled (also used epoxy to seal the compass face edge).