COMPASS, PRISMATIC, Mk3 (by Peter Laidler)

[JamesMac]

Peter,
I have a 1939 Mk III which needs glass - both cover and bowl. Since trademarklondon is no longer accepting compasses with radium for repair, where would a person obtain these parts? Many Thanks!

[DaedalusWren]

Excellent and concise thread Peter. I appreciate the time you have taken to do such a great article. I to am getting into refurbishing and repairs of these compases and have had a difficult time at finding replacement parts for them, ie. Lid glass, screws, seals, tritium lights etc. if you could possibly point me in the right direction it would be greatly appreciated. I live in Canada but am not afraid of over seas ordering if i know I am getting the proper parts. Any and all help would be greatly appreciated. Thanks. Wayne.

[SEITENGEWEHR]

I was under the impression that Distilled Kerosene was the fluid used in British Military Prismatic Compasses.
as I personally own 4 Prismatic Compasses and have used them to cross the tundra
beyond Barrow up north of Alaska.
They are the Finest Compasses Made.IMHO




QUOTE=Peter Laidler;183395]I didn't realise that there was a comments page or I'd have answered earlier!

Most people won't have the equipment that you or I have (had) access to nor the damping fluid - and that's all it is, a damping fluid. I'd like to say that the 'QM's' method you allude to is a bit, well, derogatory really because I was taught to repair compasses using the EMER method and have to say that so far as I am aware, have never butchered one yet although I have broken a few rotating bezels by not pressing them on with the flat press adaptor!

You mention that the article was akin to taking your Rolex to the butchers too. You'll probably have guessed that we were also taught wristwatches too and I've cleaned/repaired/rebuilt many of them. Obviously not Rolex's because we didn't have them but we did have and clean/repair/rebuild to EMER spec. the tat that we did have, such as Omegas, Longines, Jaeger le Coutre, Eterna, Record, Vertex plus some. Not Rolex I agree but.......... Well, the two Omegas that I did liberate plus the Longines that I gave to my son a couple of years ago are still running like, er.........., clockwork!

I've got a couple of calibrated compasses here and due to the lack of Isop, are now filled with degassed methylated spirit - and still going strong. So while it might not be to the original spec, it is as good as Joe Public can get and it works[/QUOTE]

[Peter Lumb]

I am a compass maker by trade, and this article, while obviously written in good faith, gives fatally flawed information that will lead people to carry out work on beautiful, precision instruments, that will do such damage as to possibly render the compass beyond economical repair.

Over the years I have been asked so many times to repair bad servicing that I have lost count. I often wondered why on earth people would use putty or mastic instead of the 20pence purpose made o-ring that would be correct for the job. Mastic destroys the compass, it weeps into the fluid and coats the interior in such a way that it causes incorrect operation of the instrument. Basically it makes a mess and cam never provide a good seal, and for the compass maker who has to repair the repair it takes hours to remove. It is not just amateur, it is criminal. To seal the sealing glass you use a purpose made D profile o-ring that costs pennies, nothing more.

Special press to press down the sealing glass and mastic? Not really

Surgical spirits? Not really

PLEASE, anybody who has a G-150, and M-73, a MkIII or any other wonderful precision instrument, PLEASE do not follow Peter Laidler's instructions. I am sure he wrote them in good faith, but following those instructions would be like taking a Rolex watch to the butchers to be serviced... you WILL end up very disappointed and with an instrument that will probably then cost more to put right than the actual value of the instrument.

Peter, if you want me to re-write the article for you, and re-post it under your name in such a way not to unwittingly lead people to wreck their instruments then I would be happy to do so.

The average liquid prismatic compass comprises over 120 component parts. Working on these compasses is comparable to working on a wristwatch... you need special tools and to treat the instrument with respect and a delicate hand.

There is the QM's method of "repairing" compasses, and there is the compass maker's method... one leads to tears, the other leads to an instrument that will survive wars, arctic and desert conditions and that will last so long it will be passed from generation to generation as an heirloom.

I realise this is a fairly judgemental "first post" for a forum FNG, but the article will lead people to unwittingly destroy their compasses.

What size D Profile 0 Ring will I require for my Stanley Prismatic Compass?

[Badger]

For the 100th time...

These comments sections are not designed for interactive feedback, only comments about the articles. In the case of this type of library item, try posting your question in the Enfield Collectors Forum (click here).

Regards,
Doug