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cross hair wire.

dsergison

Diamond
Joined
Oct 23, 2003
Location
East Peoria, IL, USA
I am repairing a David White transit. The cross hairs are gone, I need a fine wire to lacquer in place. the mount is still there, and it has grooves where the wires used to sit so locating them shouldn't be trouble.

Where might I get some really fine wire? .001" or so? I have no idea what is appropriate thickness as the origionals are completely gone. I would imagine it would have to be on the very thinnest of scope hairs?

and should I black them somehow? I could try to dye the wire for better contrast, or would that be unnecessary.

if anyone has some and would like to sell a small length I would be very interested.

Thanks, Dan
 
many years ago ,i replaced x/hairs on a target scope w/ nylon from the TOP of womans stocking ...kept dissecting till got down to single thrd ,weighted ends w/large heavy spring type pa per clips & hung them over the mount & glued in place ....maybe duco
cement ....it has been near 50 years ....15 x scope ....little thicker than original ,but worked

best wishes
docn8as

ps ...see if unertle still in business...also a target scope repairman in ross ohio ...might cud get name
 
Here is an idea that worked for me. Get some brass wire as is used in wire edm machines. Try to get .010 or smaller. lay it on a surface plate and lay a shim of the final thickness you want on each side of the wire. Roll something like a mandrel over the wire till it is thin. When putting the reticle frame together turn the wire under magnification till it is end on. It is possible, then, to rotate, or twist, the wire ot the top and bottom a quarter turn in opposite directions to look like it is thicker at the top and bottom but thin in the middle. Hope this helps. Perry
 
I remember seeing a TV program about spiders when I was a kid, and they were showing someone "harvesting" the spider's web strands around a sort of kite string spool (two dowels fixed apart about 6"). They said that it was the strongest material known of that fine size and was used for cross-hairs on various scopes. It might be worth a try.
I think they were havesting black widow, which is fairly easy to find most anywhere, and not as dangerous as we thought when we were kids (unless you're allergic). Just get it dangling and spool it up as the spider lowers himself down.
And don't let it bite you. Should give you months worth of crosshair if it works.
 
Jeff223, that wasn't *red* hair by any
chance, was it?


And I think black widow venom is just about
as potent and necrotizing as it ever was.
I think I'd take a pass on collecting that,
even I could find some around here!

Jim
 
Saw a description in an old surveying manual on repairing dammaged cross hairs. They suggested spider web as well. The technique described was to split a green twig about 1/2 way down and open it up a little wider than the ring the cross hair mounts to. Then glue the spider web to the stick and advance the split with a small wedge until the spider web was tight and strait. With the strand fixtured, you placed it on top of the cross hair ring and glued it down with a drop of varnish. Sounds simple, but I never had need to try it.
 
Saw a description in an old surveying manual on repairing dammaged cross hairs. They suggested spider web as well. The technique described was to split a green twig about 1/2 way down and open it up a little wider than the ring the cross hair mounts to. Then glue the spider web to the stick and advance the split with a small wedge until the spider web was tight and strait. With the strand fixtured, you placed it on top of the cross hair ring and glued it down with a drop of varnish. Sounds simple, but I never had need to try it.
 
The spider guys are right... according to Buff & Berger's book on instruments they used spider webs except were Platinum wire was specially ordered........ and they go on to say the spider of choice is a Black wood-spider (is that the same as a black widow? I don't know my spiders and have no intentions of getting close enough to learn more)..... anyway the instructions go on for about a page...... let me know if you need it and I'll scan it...
 
Jim, Rivett608, and Company --

Spider silk was the most commonly used fiber for reticles in traditional surveying and other scientific instruments for two reasons: 1. The typical fiber diameter is in the 0.00025 (read that as "a quarter of a thou") inch range, allowing high-magnification eyepieces without making the reticle look like a telegraph pole. 2. Spiders are reasonably common everywhere except in the arctic, allowing expedient replacement of broken reticles in the field.

(Even today, some survey equipment repair shops keep a few spiders in a terrarium, on call to make silk as needed. There will often be a "slingshot frame" made of bent wire or cut from wood nearby . . . the repairman catches a spider, sets it on one leg of the Y, and flicks or blows the spider off its perch. As the spider descends on his web, the repairman will wind the filament around the Y's until he has collected several feet of web.)

W & L E Gurley of Troy, NY was probably the first major instrument maker to generally abandon spider silk by making drawn platinum wire their standard filament in (IIRC) the closing years of the 1800's. Using platinum reticle wires overcame the hygroscopic length change of the silk, which could actually get long enough to sag or short enough to break if the change of humidity was severe enough.

One late-comer to the survey-equipment manufacturing business, Brunson Instrument, used glass fiber for many of their fiber reticles. I've heard from two different sources that Brunson drew their own glass fiber, using a single child's glass marble as their source for hundreds (or maybe thousands) of yards of fiber.

But glass's major use in reticle making has been as a see-through substrate for photo emulsion, vacuum-deposited, or etched-and-filled reticle lines. The patterns on the first-generation glass reticles simply emulated the taut-filament patterns of conventional reticles, but somebody figured out that "straightness" of the reticle lines no longer depended on tension in a fiber.

This realization soon led to stubby tic-mark stadia, and filar-bifilar, varying-width, wedge-on-one-side-only, and open-center reticle patterns for the instrument's principal line-of-sight.

I've only repaired reticles on "user" instruments, and favor glass fiber although I've also used a filament unravelled from a silk thread taken from an old necktie. Fingernail polish is the easiest to use "glue" for attaching the fibers to the reticle ring that I've found.

Incidentally, some old survey instruments featured "disappearing stadia hair" reticles that had the crossing filaments for the principle telescope line-of-sight on one side of the reticle ring, the parallel filaments for the stadia reticle on the opposite side of the ring.

The limited depth of field of the eyepiece (which is, in reality, a microscope) made it impossible to see both the main and stadia reticles simultaneously . . . which totally prevented the classic "wrong hair" pointing / reading blunder.

Incidentally Mk II, at least one traditional survey textbook identifies the "brown [recluse??] spider" as the preferred source of silk for reticles while almost dismissing black-widow silk as second-rate but easy to find.

John
 
I hate to bring back such an old thread, but this seems to be the only place on the web talking about do it yourself scope repair, and I'm seeing a lot of knowledgeable people.

I have an old Hensoldt 4x28 rifle scope from Germany that I got as a basket case. I'm trying to get it put back together to mount on my AR-308.

How well would the ultra thin copper electronics wire sold at radio shack work for the reticle?

Here is an idea that worked for me. Get some brass wire as is used in wire edm machines. Try to get .010 or smaller. lay it on a surface plate and lay a shim of the final thickness you want on each side of the wire. Roll something like a mandrel over the wire till it is thin. When putting the reticle frame together turn the wire under magnification till it is end on. It is possible, then, to rotate, or twist, the wire ot the top and bottom a quarter turn in opposite directions to look like it is thicker at the top and bottom but thin in the middle. Hope this helps. Perry

So would this only work if you press the wire? Ideally I'd like to do a duplex reticle of some sort. Are there any other ways to do this that I might consider?

Looking at the parts inside the scope, the lenses assembly that moves in order to focus the scope has a roughly 1" wide groove machined into the side the aluminum body that holds all the lenses together. The groove is packed with some sort of grease, so that it is in contact with the inside of the tube as the lens assembly moves inside the tube. I'm thinking that it would be a good idea to replace this grease, since it's rather old, and much of it is missing. Does anyone know what would be the best grease to use for such an application?

Does anybody have any ideas on how I might go about charging the scope body with nitrogen?
 
Locate a pure metals supplier or a supplier of consumables for the semiconductor industry. Pure tungsten wire - very stiff and strong - is available in sub-.001 diameters.

Hundreds of YARDS of .0005 dia tungsten wire were used annually at the small division of Fairchild Semiconductor where I worked back in the day. Can be cut with normal hand tools, easy to work with ... and did I say VERYs strong ?
 
TempestV --

For many years the US Government specification for various types of survey and similar telescopic instruments required the use of MIL-G-23827 Aircraft and Instrument Grease for internal-to-the-telescope lubrication. Both Aeroshell Grease 7 and Texaco Low Temperature Grease EP were on the MIL-G-23827 Qualified Products List -- there are others, but the Shell and Texaco products are the easiest to come by in small quantity.

Of course, Shell and Texaco both think 30 pounds is a small quantity.

I've gotten my supply by taking a small, clean, and covered container, a spatula, and a few clean paper towels to a "Fixed Base Operator" (FBO) -- essentially an aircraft service garage -- at an airport and asking them to sell me a few ounces of the grease. Both places gave me a half cup or so of grease without charge, specifically mentioning that they appreciated the fact that I brought the container, spatula, and towels.

John
 








 
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