I've seen the relatively inexpensive import scopes for about $200 but was never really sure about them... the one thing I did know was that they'd be too big for my watchmaker's lathe... I really wanted something smaller. The "nice" ones are pretty expensive and I'm still not sure how small you can get them.
Recently I was thinking about the possibility of making my own, when I remembered a pair of inexpensive Bushnell binoculars that were sitting in my junk drawer because one of the kids had broken one of the eyepieces. I had already taken it apart to see if it was easily fixable, so was familiar with the optical components... specifically, I recalled the pair of prisms each barrel used to flip the image. I started tinkering around, mocking up the various lenses and prisms to see if I could get good magnification with a reasonable focal distance, viewable from an eyepiece angled to the scope's line of sight. It started to look pretty promising, so I set about making some parts for a prototype.
I turned and milled a piece of 1040 steel to hold the prism, and to provide a shank for mounting in the tailstock. I turned a couple of pieces of scrap brass pipe to form the body and eyepiece. After notching the eyepiece with an end mill, I soldered the two together. This pic shows those pieces, along with the lens and prism I planned on using. You can see the prism is badly chipped on one end, that was my fault for being careless while test fitting it. I have another one I can use once everything is ready to be assembled for the final time.
These are the assembled components:
And here you can see the image through the eyepiece hole:
I quickly modified one of the fittings from the binoculars to secure the lens and attach it to my scope, and that let me give it a trial run. I started by mounting the top plate from an 18 size Waltham pocket watch in my faceplate. I roughly centered one of the jeweled pivot holes using the tailstock center, and then mounted the scope:
It's tricky going without the reference mark, and with the image flipped in one direction, but I was able to get the jewel hole centered with a minimum of fiddling:
I was pretty encouraged by the results, so I went ahead and made a proper fitting for the lens. I decided to use brass, and make a fitting the same way brass and gold jewel settings were made in watches, before friction-fit jewels became the standard. I turned a recessed seat that the lens would slide into without friction, then around the outside of that I turned the brass down to a thin lip. I placed the lens in the seat (a few drops of oil kept it held in place), then ran the lathe and applied a lightly oiled burnishing tool to the thin lip of brass around the lens, to close and burnish it over the front edge of the lens. I also made an eyepiece by turning a fitting from black acetal, that one of the large subject lenses from the binoculars would snap into. Here were the parts at this point:
That's all of the pictures for now. After taking that last one, I washed the brass body in warm soapy water, then soaked it in vinegar for a while, rinsed it with denatured alcohol, air dried it, then primered and painted it. Once the paint is cured, I suppose it will be "done"... although I do need a cross hair or something in the lens. I was thinking of maybe scribing it with a carbide scribe, then trying to fill the scratches with black ink. Any other suggestions are welcome... but ideally I'd like the lines to be really thin.
I'm not sure if this thing I made is as good as a $200 chinese scope, but it works a whole lot better than not having one at all!
i belive they use orb web filaments in telescopic sights sorry coud not find part one
