Cement for RF optics?

[Grytpype]

Can anyone suggest an adhesive or lacquer, available in the UK, for securing the lenses/glasses in rangefinder and viewfinder assemblies? Ideally it would want to be liquid so that it can run into gaps, non-shrinking so that alignment doesn't change as it sets, strong but removable, and non-stringing

If it was also black, that would be a bonus, but is not essential!

 

[farlymac]

Never use any CA type adhesives (cyanoacrilate) on camera optics, as it will permanently haze them over time. As to what's available in Britain, I don't know, but I use a product called Weldbond. It may be similar to Pliobond, but any good contact cement should do if applied lightly, so as not to change the alignment of the mirror.

PF

 

[Grytpype]

The trouble is, all the contact cements I know do shrink and string. Really it needs to be something non-solvent based, that cures without shrinking.

Something I'd considered is some polyurethane seam sealer I bought for a job on the car. It moisture-cures with little or no shrinkage - and it's black as well! It fails the liquid requirement, though, and it does string.

The immediate need is to fix the lenses/prisms in a Contax rangefinder, and the cement really wants to be able to run into the clearance between the lens and the frame.

 

[Vickko]

I think I know the repair you are doing.

I used epoxy mixed with black paint.

You can "tune" the viscosity of the epoxy a bit, and I think the "liquid metal" version of it is metal powder mixed into the epoxy.

 

[farlymac]

He did say it is a Contax rangefinder.

PF

 

[Grytpype]

I used epoxy mixed with black paint.

I think the sort of liquid epoxy resin used for laying up fibreglass mat or epoxy 'potting' compound might work quite well.

The problem arises if you don't get it right first time or need to strip it down in the future! I think possibly a soak in acetone would shift it, but it would shift any paint as well.

 

[dubya]

You might look into G-S Hypo Cement available from Micro-Tools (Fargo Enterprises). According to the label: "Pinpoint precision for crafts, hobbies, watch crystals, optics, industrial applications"

I use it to glue small windows and the like. It is clear and non-shrinking but it is sort of stringy... smells like model glue. I've not tried in your application tho'.

http://www.micro-tools.com/

From the US storefront but this is the stuff:

http://www.micro-tools.com/store/P-GLU-105-00/Gs-Hypotube-Cement.aspx

Wade

 

[Grytpype]

The GS-Hypo Cement turns out to be quite easily obtainable here in the UK. I'll get some I think, because even if it turns out not to be ideal for this job, it looks as though it could be just the ticket for locking screw-heads etc, which I normally try to do with contact cement and make a horrible mess!

I've been wondering about resin wood glues. Being intended for porous surfaces, adhesion might not be adequate, but on the other hand, it is mainly just filling the clearance between glass and metal, and if it does need doing again it should be removable without solvents. I'll need to do some more research and some experiments.

 

[mikemc_photo]

Don't forget about discoloring as it ages. Most epoxies yellow over time, GS will not

 

[colyn]

If I recall there are 2 prisms in the Contax rf prism. If you clean off the amber mirror coating between these 2 parts the rf will not have a rf spot since this coating is the same as the half mirror of other rf cameras. In other words you will be able to view but will not have the ability to focus.

The best glue I have found for bonding to glass parts together is here http://www.micro-tools.com/store/P-...lue-Adhesive-For-Crystal-Glass-And-Metal.aspx

Once you properly align the parts you then expose it to uv such as direct sunlight in order for it to cure. I have used this glue for repairing loose yellowed meter prism blocks on the Minolta srT cameras after cleaning off the old adhesive..

 

[Grytpype]

I probably should have explained more clearly what I am aiming to do. It's described here on the Kiev Survival Site if you scroll down to the section on vertical/rotational alignment. You set the alignment of the fixed plano/convex lens by wedging it. I would then partly glue it to fix the position, remove the wedges and then finish glueing solidly. It's not a job you would want to have to do twice if you can help it!

I've located online some black epoxy that I might try but I'd need to get it right first time. I'll do some more researches before I decide.

Thanks for all the suggestions.

Steve.

 

[normclarke]

For lens and prism glueing Edmonds Scientific market a UV curing adhesive that is ideal for this purpose, don't use the cheaper more widely available substitutes.

Best,

normclarke.