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Old 09-09-2020, 10:34 AM
CDSteding
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Delamination of lenses



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I have a Weaver J 4 scope, some of the lenses have started to delaminate. Both ends of the scope have brass housings that hold the lens. I am soaking them in acetone and can see it creep between the lens. What I'm having an issue with is getting the lens out of the brass housings. Are they held in with the same type of glue that the lenses are bonded together with? Any help would be appreciated, even a best guess.
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Old 09-09-2020, 11:01 AM
Mr Fishhead

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Heat.
Put the lens assembly on top of an incandescent light bulb and the "glue" will melt. Push the doublet out of the brass holder and slide the lenses apart, and WAIT FOR THEM TO COOL OFF before doing any cleaning to them ( I wait an hour). Cleaning a hot lens can result in the lens cracking.

Keep everything correctly orientated .

Hope this helps,
Dan
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Old 09-09-2020, 01:47 PM
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'ol shooter
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Also, link to a good article on glued lenses:

http://jimshomeplanet.com/lensglue.html
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Old 09-09-2020, 08:32 PM
CDSteding
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Thanks all, much appreciated. I'll give it a try this weekend.
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Old 09-11-2020, 03:12 AM
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Had same issue with a k6 im working on I had to soak lenses in xylene in a jar for about a month to soften the balsam between the lenses, then heated steel ring lightly with propane torch just waving it around the edge while it sat on a piece of plywood, not on lense and pushed them out and then they fell apart. Mine looks like it was glued in with ferrule cement like I used 40 years ago for glueing arrow tips in aluminum shafts. I bought new fresh balsam to reglue them with. This is my first attempt to fix a two piece lense. Aaron

Last edited by aaron10; 09-11-2020 at 03:18 AM.
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Old 09-11-2020, 12:28 PM
CDSteding
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I've had no luck so far. Soaked it in acetone for 3 days started to see some of the glue between the lenses dissolve but still no luck with getting it out of the brass ring. Next I tried boiling it for about 30 minutes and then used a wooden doll of the same diameter as the lens and tried tapping it out again no luck. I'm going to give your exact method a try, thanks very much for the advice. One thing I have had luck with is converting broken crosshairs over to post reticles. Also had some very good results with nitrate bluing the tubes after cleaning them up. Thanks again for the advice it's much appreciated.

Last edited by CDSteding; 09-11-2020 at 12:35 PM.
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Old 09-11-2020, 01:42 PM
CDSteding
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Let the good times roll.
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Old 09-11-2020, 11:13 PM
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Originally Posted by CDSteding View Post
Let the good times roll.
I was warned not to get lenses to hot cause it might break so go easy on the propane torch , keep it on ring going around it and try to push lense out , it may take a bit of heat. After it all cools the lense can be cleaned of balsam with acetone or xylene with soft cotton cloth. I will add mine was already pretty hot as it went from the boiling water bath right to the heating with torch. Maybe I will try my oven next and just work up the heat a bit at a time.

Last edited by aaron10; 09-12-2020 at 11:41 AM.
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Old 09-12-2020, 06:02 AM
Mr Fishhead

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Quote:
Originally Posted by Mr Fishhead View Post
Heat.
Put the lens assembly on top of an incandescent light bulb and the "glue" will melt. Push the doublet out of the brass holder and slide the lenses apart, and WAIT FOR THEM TO COOL OFF before doing any cleaning to them ( I wait an hour). Cleaning a hot lens can result in the lens cracking.

Keep everything correctly orientated .

Hope this helps,
Dan
The problem with heating the lens assembly with a propane torch is if 1 side gets hotter than the other side, the lens can crack.

I've fixed many delaminations with heating them up with a light bulb and in the winter, the lens assembly's get put on my wood stove to "melt" the glue. The light bulb heats more "evenly" than a propane torch.

I've tried using acetone and other chemicals for separating lenses, but using heat (light bulb) works best and fastest. After the lens cools (for about an hour), then I use acetone to remove the remnants of the glue.
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Old 09-12-2020, 07:23 AM
sweetmk
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Quote:
Originally Posted by Mr Fishhead View Post
I've fixed many delaminations with heating them up with a light bulb and in the winter, the lens assembly's get put on my wood stove to "melt" the glue.

The light bulb heats more "evenly" than a propane torch.

I've tried using acetone and other chemicals for separating lenses, but using heat (light bulb) works best and fastest. After the lens cools (for about an hour), then I use acetone to remove the remnants of the glue.
You will probably need to be more specific, as to the bulb,,

For 20 years now
, my bulbs have been CFL, and now, even worse,, LED,,,

I am almost positive that a REAL incandescent 100 watt bulb could crack a lens, if it were too close,,

Maybe a 60 watt,, or, maybe it only needs a 40 watt??
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Old 09-12-2020, 04:32 PM
Mr Fishhead

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I use a 40 or 60 watt bulbs as that is what I have. 120 volt, non-halogen.
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Old 09-26-2020, 04:53 PM
CDSteding
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Did it, just a bit of time and heat.
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