Dry Compass

[CINDERS]

I have just procured a compass and after having read Peter Laidlers article on the Mk III compass I would like to ask what type is this one pictured.
As it has similarities to the one Peter Laidler talks about but has no top grill guard all I can find on it is an engraved 607! on top and stamped 274 inside the top no M Mk anywhere.
Also what has me perplexed is from my Mk III ones this one is dry where the swinging card is which leads me to think the fibre washer is kaput.
And before I get to trying to solve the problem and not create havoc I would like it identified and whether it infact came with a dry center so to speak and as always TIA
I gather the correct liquid they used is unobtainable to the public probably because it is very nasty but apart from Mentholated spirits is there anything else on the market that will suffice.
If Metho is it then no probs there.

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[browningautorifle]

Just got my MkIII Compass back from Trademark London Bubble in prismatic compass

Here's a couple of threads about these that also describe the contents and how to service them. I never got on with those compasses. We had the Sylva Ranger on standard issue, I was given one of those in Australia in '77 to use but couldn't get use to it...

[CINDERS]

Managed to get the Iso - whats it called, now the question as I only have a small quantity though more than enough to fill the compass if I wash it out with metho are the two going to react if I refill it with Iso suppose I could look at a MSDS sheet for compatibility!
Thanks Jim

[browningautorifle]

Ask Peter Laidler, he's had do with bags of them I think. It's one of those fiddly things they let the armorers do...

[CINDERS]

I have read Peters Thread on the Mk III and whilst I feel confident in doing the task on further inspection the unit requires a FTR I cannot say whether it suffered more than the broken cursor glass but it has among other things missing screws and the prism is cracked you can still read the card but its broken and thats that, so I will have a think if I want to sent it to the UK.
I did pm Claven and ask what it cost to have his Mk III repaired but he may be away as I need to get some idea before I say to my wife its going to cost $X to have this brought up to almost original.
I guess in Peters world they would scrap it for what they could utilize but they are not that common and when they do come up for sale they do attract a hefty price tag.
My trip to town was not totally wasted picked up 5 complete though fired 30mm rounds so that gives me a nice 1/2 dozen now so that was the flip side to the Iso.

Thanks for the reply Jim

[Peter Laidler]

As a general rule, if it is empty or has a bubble in it, then it's empty or bubbled for a reason- it leaks. And no end of re-filling and degassing will fix the leak. We would do everything outside the bowl in the instrument shop but the bowls were always done in the big Base workshops.

[CINDERS]

Guess I will wait for a reply from Claven to see if it goes o/seas or just place it back in the safe it would be nice if it was working anyway that's about it......

[Vincent]

Interesting.

Should this one be liquid filled?

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[Peter Laidler]

We didn't put ours in a safe - or near anything like that! They went in a wooden cupboard in the G-10 stores.

Re the dry compass. It's always worth remembering or bearing in mind that the isoprophyl is simply a damping mechanism for the dial that has a low liquid refractive index. You can use it dry provided you wait for the dial to stabilise. And a dry one is a zillion times better that one with a bubble in it.

And when you are fixing your own, please, please, please don't use steel screws................. Yep, seen it done more times than I can remember. Just look at them on the tables of the make-a-fast-buck merchants at your next gun show. Ho, ho, ho, ho! I used to tell them but they all seem to know best............. So now I don't bother!