fixing an iris blade on a 480mm boyer apo-saphir

[peter_chiappini]

Hello, I was wondering if anyone knew how to fix or replace the pin

on an iris blade. The pin came out cleanly and the iris blade is in

good condition. I have both but I can't get the pin to go back into

the blade correctly; the hole where it is suposed to fit is a little

too large now. Thank you, Peter

[john_shriver]

The deluxe approach would be to send it to S. K. Grimes.

 

You might find a watchmaker with a watchmaker's lathe and a staking tool, that's what it takes to do the job.

[User_503771]

Maybe you could build up the hole a little bit with a light coating of epoxy, then epoxy the pin onto that. Kind of delicate, but reversible if you screw up. (Common fingernail polish remover, or acetone, will remove epoxy.)

 

You could practice with a scrap floppy disk and a piece of toothpick. The scrap floppy is of similar thickness to many iris blades. I even used one once to make a new blade for a barrel lens I had. Worked like a charm.

 

If the blade is oil free the epoxy should bond just fine. Some types of superglue also work well, but it sets up a little too fast for my taste. 5-Minute Epoxy is great stuff, and strong. Or the regular kind if you've got more patience or want more working time.

 

You just have to make sure your coating of epoxy doesn't leave big ridges that the other blades will hang up on.

[colin carron]

A last ditch suggestion in case you have no other option : If the iris has a lot of blades, say a dozen or more, then losing one may not make a huge difference to the aperture. It will just look slightly pear-shaped. You will be able to check the aperture shape by just moving the dodgy blade to one side and seeing what the rest look like. In your situation I did a little dentistry. By grasping the dodgy blade with a pair of pliers and pulling it without bending the other blades, I sheared the remaining pin and the blade was extracted.

[peter_chiappini]

Hello, thank you all for the suggestions. I would't worry about it, but it leaves a little space on the outside when stopped down to f/64 or so. There is a slot for waterhouse stops or maybe filters or both and I've never actually used an f stop that high so I guess it isn't that big of a problem. Theres 18 blades, counting the one thats off, and I did think about moving them around, but that would be a last resort thing like you said. John, when you said I would need a watchmakers lathe did you mean that I would have to grind a new peg? My friends grandfather was a jewler so there might actually be one just laying around. The epoxy idea sound like a good idea, and thank you for the tip about the floppy disks, I have another camera that needs a shutter blade, and I honestly wouldn't have thought of that. Thanks again, I'll post again if I am successful.

[peter_chiappini]

I think I got the pin glued down securely with superglue gel. The first time I tried it came off after a while, then I tried with jb weld but stuck it on the wrong side; it came off easily though, even after setting for a day. The good thing is that doing that left some of the epoxy in the hole and the last time I glued it it seems very secure. The other end went in fine, I just needed to stick a small screwdriver through it to get it right. -Peter