SLR mirror replacement

Sometimes I need a new 35mm SLR mirror and the ones that I have for replacement happen to be a bit too big for that particular camera. Has anyone ever cleanly CUT a larger mirror in order to make that mirror fit a particular SLR? I have never used a glass cutter and do not even know if this tool would work in this (tiny) case. - David Lyga

I've never tried it, but a couple of thoughts .... The traditional rolling wheel cutter typically requires a good bit of pressure and pops up little chips -- not likely a good idea. There are scribers with industrial diamond tips that would likely be a better choice. One can also get cylindrical diamond grit cutting bits for use in a Dremel or similar rotary tool which could probably be used if one just needs to "sand off" a millimeter or so by working in from the edge.

The major problem I see with any such work is avoiding damage to the mirror, which I believe is a "first surface" type and very vulnerable to damage.

David Lyga said:

...the ones that I have for replacement happen to be a bit too big for that particular camera....

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It is very difficult to cut a small slice from glass. I have seen professional shops use a belt sander to remove small amounts or round corners.

using a new cutter is the trick. a little smear of paint thinner on the glass n run the wheel at a steady rate with gentle but sure preasure. you'll hear that distinct sound as the glass micro fractures under the wheel. work on a hard clean surface. cut first surface mirror from the back side, not the silvered side.

with practice, you can remove slivers as small as 1\16". its just a feel for the material n tool. to take that small pice off, use special glass running pliers or drop jaw pliers.

an easy way to remove small amounts of glass to size it, use a fine emery cloth. i use a belt sander but you can just do without, just takes longer n a bit of elbow grease.

*caution... wear eye protection

Interesting replies for someone completely ignorant of how to cut glass. I am learning something. Thank you. - David Lyga

I cut thin 2mm glass for this project. It was not very difficult. (there was a url link here which no longer exists)

I have a spare mirror I removed from an Olympus OM-PC if that is of use. I could measure the dimensions if need be.

I think (from experience) that the problem will be not damaging the mirror surface as previously mentioned... this is very sensitive to contact of any kind

David Lyga said:

Sometimes I need a new 35mm SLR mirror and the ones that I have for replacement happen to be a bit too big for that particular camera. Has anyone ever cleanly CUT a larger mirror in order to make that mirror fit a particular SLR?

Click to expand...

The critical dimension for an SLR mirror is the thickness.

There's no good hobbyist way to change that while maintaining the front and back surfaces parallel, as they must be.

- Leigh