COMPASS, PRISMATIC, Mk3 Restoration?

[Gurn]

A big thanks to Mr. Laidler for the parts to put the compass back together. Thanks for the extras!

Information

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[Gurn]

A few updates. Body painted and new screws added. Will have to touch them up later. New foot cut from rubberized cork. Might not be correct but I think it looks good for now.

[browningautorifle]

It's looking very good. I've never seen on in that condition. Ours were always hammered to crap...well used that is.

[Peter Laidler]

I'd take the lid prism cover off (the orientating strap) and sweat it/soft solder to the case cover THEN screw the screws down while applying heat. This'll firmly lock it in place forever and it'll be doubly secured by the c/sunk screws

[Gurn]

Decided to not replace the paint on the dial marker after trying unsuccessfully different paints and clear adhesives mixed with glow powder. Nothing seemed to hold up during tests against the alcohol.

The o-ring ( Thanks Mr. Laidler) goes on the upper part of the glass and is squeezed into a grove by the outer ring. I decided to try a modification of my own. I don't like the way the glass sits on the bowel base as there is a little raised area running all the way around. I worry about cracking so as watchmaking is another hobby of mine I have a supply of very thin flat rubber washers and found one to fit in there. So now the glass is sandwiched between two pieces of rubber. Everything tightened down nicely. If you take time and turn each screw about 1/4 turn as it gets tight in a cross pattern I don't see how anyone could break the glass.

I made my own simple vacuum chamber and filled with 99% isopropyl alcohol. With the fill port to the top so air can escape I first used a Mitty Vac pump. This got most of the air out. Then by using an electric vac pump it got it all out. Its amazing to see the whole unit bubble away under such vacuum.

Here are a few pic of the process. Sorry for the lighting, its hard to make out the o ring and flat ring but there is a pic of each step.

More to come in a few days.

[Peter Laidler]

We had a set method of tightening up the 8x cover ring screws. 1, 4, 7, 2, 5....... Ie, every 3rd screw ands go round several times tightening up tighter and tighter until after several times around the circumference, they'd be tight and hopefully spirit tight! Where did you find the filler screw seals?

[Gurn]

The seal was in good shape so I figured I would see how it holds. If it leaks I might try an o ring.

[Peter Laidler]

We have a law in the UK and it reminds us that if something can fail, it will. It's called Sods Law! If you do find some new ones - or fibre ones that fit, let me know!

[Gurn]

Will do.

[Gurn]

More work today. Cover window glass was broken so found the right size pocket watch crystal and scribed a line and filled with black paint. Not perfect but I only have two crystals that are the right size so its going to do. Glued that in place then started on the white fill. That is tricky. I found the only way to decently do it is to use water base gloss and dab it on in a small area at a time. Then quickly wipe with my finger. Tried doing it with damp cloth and with dry cloth but most of the paint in the groves came out too. When its dry I hope to be able to clean it up a little better. Next I made up a little glow paste. Used some clear adhesive and mixed in the glow powder. I could have just used white paint but this looks a little more original to me .

More to come.