# Removing the glass from a lens filter



## Paul_in_Maryland (Sep 19, 2005)

I just bought this 39mm glass filter (UV, multicoated) in the hope that the glass can be substituted for the plastic lens in my G&P miniturbo bezel. 

How do I remove the lens from the filter ring? I don't have a machine shop, Dremel, or any power tools.


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## tvodrd (Sep 19, 2005)

Paul,

Is the aluminum ring one or two piece? Was the assembly sandwiched and then swaged/pressed together? There isn't enough detail in the pic to tell.

What's with ImageShack's (attempted) pop-up and dumb-a game. My normal close (without thinking/_really looking_) has caused me to close FireFox several times lately after viewing ImageShack pics. 

Larry


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## Paul_in_Maryland (Sep 19, 2005)

I can't see any seams, but maybe two parts were pressed together and the seam is not nearly impossible to see.

I don't have a digicam; I used my scanner. Here's another scan, where I've tried to show where the glass meets the aluminum. Hope it helps.


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## tvodrd (Sep 20, 2005)

Still no help.  I'm willing to attempt to cut it loose for you in the lathe. No promises I will be sucessful, and at your risk. :shrug: (At least ImageShak didn't pull anything funny that time.  ) Send me a PM.

Larry


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## Paul_in_Maryland (Sep 20, 2005)

Hi; thanks for your offer. I think I'd rather find a way to do it myself so I could offer this solution to anyone wanting to upgrade their G&P turbohead to a glass lens. I'll try filing a notch, then twisting the aluminum till the glass can be slipped out. I'll share the results and if I fail or break the glass, I'll come groveling back to you. Paul Stregevsky


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## nikon (Sep 20, 2005)

Look very carefully inside the rim on the rear side of the filter. If you see a small gap, this would indicate that the glass is held in place by a split ring. Using a very small jeweler's screwdriver, get a grip on one end of the ring and pry it out.


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## zelda (Sep 20, 2005)

Also tried with a Stove plate?

It takes about 8-15minutes for lens with "medium" temperatur.


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## Paul_in_Maryland (Sep 20, 2005)

Nikon,
I'm afraid I can't see any "small gap." If it's there, it's too subtle for my eyes. By "rear," I'm assuming you mean the face that would normally be hidden if the filter were mounted on a lens. Correct?

Zelda, 
Can you be more specific? I'm not sure what you're suggesting. Somehow heat the filter, then, using gloves or pliers, bend it and the lens will fall out?


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## tvodrd (Sep 20, 2005)

It all comes down to how is the window retained in the housing. The housing could be two-piece, threaded or pressed or adhesively-bonded to secure it. It could be one-piece and the window swaged/crimped, shrunk-fit, or adhesively-bonded in place. I doubt a shrink fit because of the tolerances required and the stresses that would result, given the differences in thermal expansion coefficients for glass and aluminum. The hot plate could release it if it were shrunk-fit and facilitate its removal if it were adhesively-bonded. (And I aint _into_ being "groveled" to!  )

Larry


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## zelda (Sep 21, 2005)

I used this methode to disassembling flat-concave lens from a Double-convex lens. After heating the lens they falling not out because it has a small vacuum. press the lens on the side. When you are heating glued lens, you can see when the glue is melting. But before remove the aluminium-ring.

sorry for my bad english


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## Paul_in_Maryland (Sep 21, 2005)

I'll try heating it up this weekend.

I don't know if this helps, but I bought the filter here; you can see several ridges in the "watermark" photo.

If you're reading the archives and the listing is gone, search on eBay for Silver SMC UV filter.


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## Paul_in_Maryland (Sep 21, 2005)

zelda said:


> sorry for my bad english


Don't worry, I'm used to hearing bad English: I'm American.  Besides, your English is better than our German or French.


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## chimo (Sep 21, 2005)

If you do not care about the metal ring, just use a dremel tool and cut through the ring on opposite sides. That should enable you to flex the ring enough to "wiggle" the glass out.

Destructive deconstruction is sometimes very fulfilling. :devil: 

Paul


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## Paul_in_Maryland (Sep 21, 2005)

I don't care about the metal ring, but I don't have Dremel. I'll use a hacksaw.


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## MoonRise (Sep 21, 2005)

Hand tools: You can try a fine-tooth hack saw. Or a triangular file. Or maybe even a pair of dykes (diagonal cutters).

Like user 'nikon' said, first look for a small split ring or retaining ring that may be holding the lens in place. If you find a ring, remove it and your lens should be free of the metal rim.

Power tools: It would be relatively quick and easy for a Dremel-type tool with a cut-off wheel to notch through the rim of the metal filter. Put notches in multiple places and CAREFULLY remove the metal pieces. The caution is to not bend the rim such that you crack the glass lens.

Have a power drill, corded or cordless? Pick up a mandrel and pack of cut-off wheels and use that in the drill. You won't have quite the finesse or 'feel' as a Moto-Tool, but it'll still work.

I'd recommend a Dremel-type tool. They're not all that expensive and pretty handy for small jobs of cutting/grinding/polishing/etc. Should only be about $50 or so.

Regarding heat, don't bother. User 'zelda' was separating individual lens elements from a glued-up group of elements. Which is NOT what you are trying to do.


Oh, and may I suggest that you pad your work area with a thick towel or blanket so that when the lens pops free of the rim finally, it doesn't fall to the floor and shatter after all your hard work?


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## Paul_in_Maryland (Sep 21, 2005)

Thanks a bunch, Mike! I have both a hacksaw and a triangular file, and the towel is a precaution I would have overlooked. 

I've given up trying to detect a split ring. I just don't see anything that looks like two pieces that can be separated.

I'll let you guys know what happens after this weekend.


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## Paul_in_Maryland (Sep 22, 2005)

I couldn't wait till the weekend! Using a triangular file, I was able to file through the aluminum with about 390 strokes. I applied the slightest twist and the glass fell out onto the carpet. 

Well, the 39mm filter was too small:

The glass measures about 36.5mm. I need about 42.5mm:

Left to right: 42.5mm plastic lens, 36.5mm glass, aluminum filter bezel after being filed open.

Why didn't I measure the plastic first? I'll try a larger filter.

Thanks to all for your guidance.


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## MoonRise (Sep 23, 2005)

Glad you were able to get the lens out.

Sorry it was the wrong size. Also, in the image you posted about, it looks like you ran the tip of the file into the edge of the glass lens and scored/chipped the edge. Not so good. Glass is a brittle material and putting a chip/score into the edge increases the likelyhood of a crack spreading across the lens. Especially when thermal stress (running a high-powered incan, for instance) is added.

Aren't you glad you were over the carpet when the lens popped out and fell to the floor?


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