Hi all members just got a om1 all ok but the mirror needs replacing dos any one know were to get a used or precut mirror. also has anyone removed the mirror or any web videos on removing the mirror would be very helpful kind regards steve
You will need to start with an original OM mirror, harvested from an OM body. The good thing is that all OM-1, 1n, 2 and 2n bodies used the same front-silvered mirror. The size and thickness of mirrors from other OM bodies and from other makes may be different.
It is possible to remove a mirror from a "dead" body without complete disassembly, but it's risky -- the mirror is quite thin and easily cracked. You will need some acetone and two or more narrow sharp-pointed hobby knife blades (X-acto?), perhaps metal tweezers as well, along with contact cement, epoxy, and some tissues. You may want to practice on the "good" body, removing the cracked mirror first.
Remove the focusing screen from the camera -- acetone and plastic focusing screens are not friendly to one another. With the camera lying on it's back, carefully place several drops of acetone along the front edge and along the sides of the mirror so that the acetone "wicks" between the glass mirror and the metal frame to which it is attached. I use tweezers, held closed and dipped into the acetone, to carry the solvent to the camera, spreading the tweezer points to drop the acetone in place. (Try to avoid dripping acetone onto the curtains below -- with luck and care, it is sometimes possible to harvest functional curtains from otherwise dead bodies -- but that is a different repair!) Do this several times, waiting 5-10 minutes each time. The mirrors are usually held to the metal frame with three small dabs of contact cement, with a larger dab of epoxy in the center. Your aim is to slowly soften the three spots of contact cement, then carefully separate the mirror from the epoxy.
This final step -- separating the mirror from the epoxy -- is the risky part. Gently, slowly, insert just the tip of your hobby knife blade between the leading edge of the mirror and the metal frame at one side of the mirror, then drip a little more acetone along the edge. Pause. Now do the same at the other side of the mirror, and add more acetone. Pause. Repeat, slowly pushing the tips of the blades between the glass and the metal frame. You might also insert a blade between the glass and frame in the middle as well. If you're lucky, the epoxy will separate from either the frame or the glass without breaking or chipping the mirror!
If you successfully extract the mirror, you may need to gently scrape the epoxy off it's back (glass) side, as well as any remains of the contact cement adhered there. Note that the silvered side of the mirror goes out, the glass side is stuck to the metal frame.
To install the mirror in the good body, first install a sacrificial focusing screen in the body -- one that is scratched or useless, if you have one. Then, remove any remaining glue or epoxy from the metal frame using acetone for the glue, or just scraping off any epoxy. Clean thoroughly with acetone.
You should see three flat "spots" on the texture of the metal mirror frame -- two near the front edge, one in the middle at the top. This is where you will put small dabs of contact cement. In the center, you will need to put a drop of epoxy. Carefully place the mirror into it's frame so that it is centered and aligned so that it's front edge is parallel with the front edge of the metal frame. Cover the mirror with tissue and gently squeeze the mirror to the metal frame with your fingers to spread the adhesives.
Now, this is where the sacrificial screen comes into play: put one or two gently wadded tissues into the space between the mirror and the focusing screen and wind and release the shutter so that the mirror traps the tissue without firing the curtains. Make sure the mirror hasn't shifted, and allow the glues to set overnight.
To check focus, use a known accurate lens and view an subject several km away -- if there is any focus error, gently urge the mirror's 45 degree stop up or down, depending on need. Don't try to actually "bend" the stop -- just influence it's position!