View Full Version : Need advice on repairing binoculars

12-29-2007, 04:52 PM
I have a pair of 60 year old WW II binoculars and the grease is all dried up and I can't figure out how to remove the eye pieces to replace the grease.Anybody got any suggestions

12-29-2007, 05:35 PM
Im sure they must screw off. use a belt wrench so you dont bite into the peices. By belt wrench its like an oil filter or chain wrench that uses a rubber belt so it cant bite and damage the workpeice.

12-29-2007, 05:40 PM
I spent several years repairing binoculars in the early 70's for Bushnell Optical. Do yours have individual adjusting eyepieces, or are they on a common bridge and adjust using a central wheel/knob? I'll assume that they adjust individually. Usually the eyecups are a bakelite type material and unscrew from the eyepiece/diopter ring. If they've been on there for 60 years they'll be a bit stubborn. Try wicking some alcohol along the bottom of the eyecup where it meets the metal eyepiece (diopter ring). A couple of small strap wrenches will probably help and will keep from marring the parts.

Once you have the eyecups removed, there are probably several (three) setscrews that will secure the diopter ring to the eyepiece assembly. Once these are loosened, the diopter ring can be removed and the eyepiece unscrewed. Be sure to mark things before removal so you can get them back in the proper relationship on assembly. The eyepieces usually have a multiple start thread.

Good luck. Like most things, it's only really hard the first time (when you aren't sure what you're doing). Post a photo, if you can.


12-29-2007, 05:51 PM
You are very wise to ask questions before digging in ... you haven't dug in yet, have you :D

One of the biggest pains in disassembling older optics (actually, same goes for machines) is undo-ing hardware without damaging it.

Can't give you any specifics but if lens rings or screws are held captive by black lacquer or other paint, put a drop of lacquer thinner or acetone on it, let it sit long enough for the paint to soften and then remove. DO NOT get acetone into the optics, however, as it will damage achromat lenses and sometimes other mounted mirrors or prisms.

Sometimes you can figure out what holds it together by examining with a magnifier carefully.

As I say this, I'm holding a pair of 1943, Taylor-Hobson 6x30 binoculars from the USN on my lap. The hard bakelite (??) eyecaps unscrew after removing a setscrew from each. After that, it doesn't look good. It appears as if the outer, straight knurled focusing barrel MIGHT unscrew from a core that holds the lenses. Can't be sure though.

Someday I need to get around to greasing these as the grease is dried up, but fortunately not binding. Den

12-29-2007, 05:52 PM
Having once worked the front desk in a camera repair shop, I can testify that optical designers use some very sneaky ways to do things. Be careful that you don't start pulling out setscrews and suddenly find yourself with a handful of parts that you can't figure out how to reassemble.

I have a vintage pair of binoculars in which the outermost ring screws off the eyepiece to reveal setscrews underneath. These could be stop screws, but they could also retain the exit pupil.

Sometimes you'll find screws underneath the leather, but peeling that off will probably ruin the leather and you'll have to find a replacement.

And the threads are most likely very fine which can be a challenge to reassemble. I have pulled apart multi-lead lens focusing mounts and have spent a half hour trying to get them back together.

Quite frankly, after watching the guys at the benches in the shop where I worked, I'd take 'em to a camera repair shop and pay the price. Shouldn't be much, but they should know the tricks.

12-29-2007, 06:07 PM
What Greg says is very true. On these Navy binocs I mentioned, there appears to be a plug or rivet that has been machined flush into the OD of the barrel that the focusing ring rotates on. This "plug" is covered by original paint so you can only see a circular shape in the finish.

Bausch and Lomb actually centered some of their microscope optics by pouring lead (or some other low temp metal) into parts of the head / eyetube assembly. Ask me how I discovered this sneaky little method :( :(

12-29-2007, 08:17 PM
The Navy tended to buy the type of binoculars with individually focussed eyepieces long after the rest of the civilized world switched to the type with a central knob which focusses both eyes simultaneously. The theory was that they were more likely to be waterproof. So beware that experience getting those Navy buggers apart may not help all that much when messing with other types.

12-30-2007, 09:35 AM
On the Taylor-Hobson Navy binocs, I see a tar-like substance at the base of each (individually focused) eyetube, supporting the sealing comment. This leads me to believe that the eyetubes may each screw into the baseplate on this model.