Compass Project -- STEP 1

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Could you get a brass screw with that diameter and thread pitch, and then cut it to size and use the mini lathe to turn the flat point on it?
 
I could make the three screws that I need from scratch with the lathe, but the lathe isn't set up completely and I just don't have the time to do that right now.

I could also simply get a brass rod and die-cut the threads, if I can find the right die. Again, hunting for that piece of equipment will take just as much time as finding the proper screws, or screws with tips that I can easily modify to function as set screws.

All the small brass hardware I can find locally is SAE, with the smallest brass size 0-90. If nobody here has an idea where to find the correct kind of screw, then I'll probably just drill out the existing threads from the compass housing, and for 0-90 size bolts. I already have that tap anyway, along with 0-90 brass bolts. I can easily modify the tip to make set screws. What I have not yet figured out if going to larger set screw is doable. The larger diameter screw might interfere with the rotating mechanism of the bezel. The three set screw are what holds the bezel inside the compass housing, while allowing to rotate the bezel.
 
I have my old Silva compass from when I was a scout in '54 ....
I'll sell it to you for $5.00
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Chinese screw tales?
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I got me some genuine Super-LumiNova (the stuff that's been increasingly used on the hands and indicators of better watches since for about 8 years) glow medium in powder form. I ran a test. I mixed the powder into clear polyurethane casting resin to make a waterproof glow "paint" with which to fill the recessed indices on my compass dial.

Cured droplet of resin with embedded glow powder:

super_luminova.jpg


Bright green (looks too cyan in the picture), glows for more than 12 hours if charged. Not toxic or radioactive strontium aluminate base. Supposed to degrade very little over even decades.
 
The dial with the cardinal points marked with lume (Super-LumiNova powder mixed with clear urethane resin). Note how the Super-LumiNova is brighter than the luminescent paint Recta/Silva uses on the needle and subdial.

As you may be able to tell, the declination adjustment is set to 15° East. You can see the declination adjustment gear peeking out at 180°. The compass base plate, which I will cut out of a piece of sheet aluminum, will allow easy access to the declination adjustment screw.

I didn't bother boxing the needle for the picture. The short thin green line will line up with the slot in the compass needle once the needle is boxed. If you look close, you can see the red clinometer indicator line right to the left of the green indicator line.

dial_lume.jpg
 
I drilled and tapped the existing holes for 00-90 (0.047") brass "screws" (bolts). I modified, or rather radiused, the tip of each, so that they function as set screws. I will have pictures once I assemble the whole contraption.

Next, I have to fabricate the lower compass housing bottom plate.
 
I haven't decided yet what to do, but I think I'll use a hardened brass tube. Then swage both ends of the tube.
 
Alright, after two months hiatus from the project, I have gotten around to making the bottom plate for the housing. The bottom plate consists of a knurled bezel (alu ring), an alu "donut" that I cut with my metal circle cutter, and a piece of glass.

I have to drill a hole with 2 mm diameter less than 2 mm away from the glass's edge through the glass. The hole is necessary to allow declination adjustment with a small screwdriver. What's the best bit for drilling a hole through glass? Something coated with diamond dust, I suppose? The glass is a Nikon filter made from tempered glass.

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The "donut" will be less recessed, because I will place a spacer (a gasket) between the "donut" and the bezel. The recess in the bezel is tapered and the "donut" with its tapered edge snaps securely into place for a tight fit.

bottom3.jpg

The glass will be glued with weather stripping to the alu ring. I will in addition put a snap ring on top of the glass. The glass should thus be protected against vibration and impact. I chose glass over polycarbonate because of optical clarity and scratch resistance.

Cost of this step: well, none, because I have all the required parts.
 
I don't think that you can cut or drill tempered glass, as it is manufactured to have a U shaped stress gradient through the glass.

relieve the gradient, and off she goes.
 
Well, I don't know if the glass is fully tempered or if it is actually just annealed. Supposedly fully tempered glass is available from 1/8" up. The glass I have is thinner. It may well be that Nikon calls an annealed glass filter “tempered.” I don't mind giving it a shot and ruining the glass.
 
My drill press had "instructions" for drilling glass. It had a dam of plasticine around the perforation, filled with kero, to remove heat, lubricate and stop flying shards.

worked OK on a couple of old jars that I had lying around, but was at 1/4", not 2mm, and central to the feed hole at the base, not 2mm from the edge.
 
I may try a diamond dust coated ball bit at high speed with next to no pressure. If it takes an hour, so be it. Agreed on making a dam and using coolant. Where are my goggles?
 
I decided against monkeying around with drilling glass once I found a piece of Makrolon polycarbonate. I sandwiched the Macrolon between the donut and the bezel. Since the donut snaps into the bezel it holds the Makrolon securely in place.

I had to make a tiny cover for the opening in the donut. The hole allows access to the declination adjustment screw in the bottom of the compass capsule. The little cover is supposed to keep dirt and lint out the internals. The cover has to lock into place to prevent it from popping open by accident. I used a dull hard metal scribe to make a dimple into a thin piece of aluminum. The dimple works just fine as intended. See the pictures.

Makrolon disc, cut sloppily with scissors -- alu bezel -- donut with cover installed:
bottom_cover4403.jpg


The face of the donut with the little cover in closed position:
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The back of the donut with the little cover in open position. I attached the cover with a brass nail and a brass sleeve that I soldered to the nail:
bottom4406.jpg


The complete bottom bezel with the Makrolon lens installed:
bottom_compass.jpg


Next, I have to find a way to install the bezel into the bottom of the compass housing. This will require drilling, tapping, brass screws and epoxy resin.
 
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