COMPASS, PRISMATIC, Mk3 Restoration?

[Peter Laidler]

I have repaired one or two -----, hundred in my time and I have bagged up a small bag of bits for you (pm sent.....) A new window lens shouldn't be any problem at all from a good glass cutter and you can carefully scribe a new marching line on the window. It doesn't have to be optical glass as you're not going to use it to locate an oasis across a hundred miles of desert! I'm always aware that there are others who have so-said done many more and know/have read much more about them than I do We modified ours to take a case guard to bar the window and at the same time soft soldered the map orientation/stellar bar to the case top as well as screws.

Just be sure to locate the horizon deflection prism properly too against the sprung spacer. And don't forget......... Never, ever, never use anything but brass on the compass. You'll be suprised by the amount to enthusiastic amateurs who use steel BA screws to repair them. Not a clever idea in my opinion learned from what'isname wot circumcised the globe. Anyway....

Refilling and sealing the bowl might tax your patience, so there's a couple of bowl sealing rings too........

Added a bit....... Surely you could just turn a new window from tough hard plasticed oroglass or something similar. And while you're doing so, turn up 10 because if YOU want a new one, then so will plenty of others too.

[Gurn]

Thank you Mr Laidler,

Will be looking forward to the parts. The glass repair didn't do to well so will be taking your advice there also.

[Chris7171]

Hi

Here is an original MkIII, Made in Australia in 1943 by J-W-H ply ltd (hard to find), 1939 date is early, good luck with the rebuild.

[Son]

Great piece, Chris. I looked for an Aussie one for ages and gave up in the end. Bought a nice British one.
I have some bits and pieces I bought many years ago for restoring an Aussie compass if I found one, but believe them to be from a later era. Peter, did the construction of the compasses change much?

[Badger]

There's also a small article in the MKL on them, as well as a picture montage...

Milsurps Knowledge Library - 1941 MkIII British WWII Military Prismatic Marching Compass

Regards,
Doug

[Peter Laidler]

We had both UK and Aust made in Oz of course but the basics from day 1 to today seem to be the same. A lot of selective and hand fitting of course. The bowl fillers in the early ones were different plus a few other things....... degrees and mils.....

[bigduke6]

There was a nice Australian one on ebay some time back needed some work but not much, here is a few before and after and some others awaiting bits or a refill,







Cant remember the paint but wasn't what I was after, but looked better than what was on there, I tried an etching primer first but after the finish coat it it was a bit too thick, but it shows were north is.






Last two, one is awaiting a few bits to complete the bowl and the other a refill.

[Peter Laidler]

The first of the Mk3 pattern had the filler screw in/through the 8 screwed sealing ring, under the rotating bezel. The 6E- prefix indicates an RAF stores issue compass

Those plastic L1A1 type were sort of OK but just not robust enough. You could replace the outer parts such as the prism and thumb ring but anything else was by means of cannibalisation of bits/innards between a few. I think they were the first ones without the cardinal points around the case and the green ones that followed didn't incorporate them either. But it did mean that they weren't classified as V&A as their value was low. I rebuilt 10 or so from odds and sods for my sons school CCF

There always seemed to be a dues-out for the tiny fibre filling screw washer.........

If anyone is stripping one down to include stripping the bowl be warned that at the rear of the bowl, inside, there is the tiniest little needle point that you can only see when it's magnified by the prism. It's this tiny needle that when it's magnified by the focussing prism (the part of the prism mech that moves up and down on the prism bars) that indicates the exact angle that you see. Cleaning the inside of the bowl with anything but a fine artists brush will damage this fine point

I don't know how you would accurately swing the compass now unless you knew someone at the local airport who had access to a calibrated mag N datum point. Nice to see them being rebuilt. I taught my little boy to map read using one

[Gurn]

Oh that is what that little needle is for. I was wondering. At least I saw it early on and was careful not to bump it. I should try and get some good close ups of the inside bowl before it all goes back together. What kind of jewel was used for the pivot socket on the card? Or is it just glass?

Nice looking compasses guys. Keep them coming, I love seeing new ones I haven't seen before. Especially the before and after pics.

[Lithy]

Here is an original MkIII, Made in Australia in 1943 by J-W-H ply ltd (hard to find), 1939 date is early, good luck with the rebuild.

Nice score mate!

I'm in the same boat as Son. Jealous indeed