New Mineral Named After GIA’s John Koivula
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 Post subject: Iris diaphragm for gemolite mark VII
PostPosted: Thu Aug 21, 2008 2:29 pm 
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Has anyone replaced the iris diaphragm on a mark VII recently? I'm curious what the best source for this may be. Some folks have said that disassembly/reassembly of the part itself is tedious; and a post a couple of years ago pointed to Edmunds.


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PostPosted: Thu Aug 21, 2008 3:50 pm 
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hi,
i've don't understood if you need to replace it or fix a broken one :?:
ciao
alberto

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PostPosted: Thu Aug 21, 2008 4:53 pm 
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I don't know if this one can be fixed. There's some corrosion and 3-4 of the blades are in the center and don't move. I'd be open to doing it either way but I've seen where other folks here said these are a hassle to rebuild. Depending on that if a good replacement can be had for say $50 it might be $50 well spent.


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PostPosted: Thu Aug 21, 2008 5:02 pm 
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mmm.....sometimes corrosion can be removed, don't know, i should see the iris. however rapairing (open, remove all blades, clean or replace and close) an iris it's a matter of method, patience and of how much you are able doing this kinda works. i've did many times and, once you've understood the method it's a matter of 10 min maximum.
besides repairing, i've never bought a new one (only spare used) but i think edmund optics could be a good source. Gene?
ciao
alberto

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PostPosted: Thu Aug 21, 2008 6:01 pm 
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As you mentioned, Edmund Optics sells iris diaphragms, mounted or unmounted. So does Thorlabs. For a do-it-yourself job, the Thorlabs website gives drawings and measurements so that you can figure out whether one will fit your situation.


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PostPosted: Thu Aug 21, 2008 6:18 pm 
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If you have the patience and hand eye coordination to make jewelry you can probably repair it. Alberto will need to tell you how to get it apart because I have never had to do the one on a gemolite but I have fixed loose optical ones and some camera shutter ones.

The key is to take good pictures and notes of how you took it apart and then do the reverse.

Corrosion can be removed with any fine abrasive or an ink eraser. Make sure the leaf is very solidly backed up so it doesn't bend.

Some curved watchmakers tweezers are helpful for assembly as is a magnifier like an OptiVisor or MagniFocuser.

In addition to the sources Dr. Brian mentioned you could ask Jeff Wildman who may be able to furnish one that will fit. mwildman@cmc.net
http://www.gemproducts.com/ He makes a similar base and will know whether his spares will fit yours.


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PostPosted: Fri Aug 22, 2008 8:47 am 
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Thanks guys, exactly what I was looking for.


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PostPosted: Fri Aug 22, 2008 10:09 am 
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The biggest headache I ever had was trying to repair the diaphragm of a gemolite at one of my old jobs. Penny wise and pound foolish sums that up.

After hours of frustrating "tinkering" with several staff members, we broke the replacement diaphragm (unbelievably flimsy and delicate component) and finally ended up sending the base into GIA for repair and replacement which is what we should have done from the beginning.


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PostPosted: Fri Aug 22, 2008 10:53 am 
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Hi,

I recall JB struggled with this long time ago and solved it. Maybe it is in the search somewhere.

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PostPosted: Fri Aug 22, 2008 11:00 am 
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My point is, why struggle?
Send it in; get it repaired properly with a guarantee and use your time to go to dinner and see a movie.

:wink:


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PostPosted: Fri Aug 22, 2008 11:37 am 
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So you bring up a third option Barbra - just have it done and be done with it :). It's why I ask here, and really appreciate everyone's experience. I called GIA just now and the stock replacement is $95 which is in the range of similar-size parts on Edmunds and Thorlabs. I haven't looked at taking this out yet but since it's so delicate I had the idea that this should have been designed to be replaced i.e. as a unit, and that if I can get the old one out, the new one should drop right in, different from rebuilding the part itself which sounds like it would take tools, patience, and experience I don't have :). I'm guessing you get at this through the back, will have a look at that this weekend.


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PostPosted: Fri Aug 22, 2008 12:32 pm 
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NTE,

Here you go


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PostPosted: Fri Aug 22, 2008 1:04 pm 
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Thanks! That's one of the earlier posts I saw. So it's not clear to me JB, once you unscrew the metal handle and get access from the bottom, does the assembly come out and go in as a unit? Or do you have to disassemble the unit into pieces to get it out and reassemble from pieces to get it back in? A nice modular design would let you drop in one of the assemblies like they sell at Edmunds and Thorlabs.


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PostPosted: Fri Aug 22, 2008 1:29 pm 
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NTE,

I can't speak for the Gemolite or others, mine is a Meiji stand and iris assembly.

In my case the entire diaphragm unit was just press fitted to a circular lip on the stage. I simply pulled it off. From there I disassembled the entire iris diaphragm unit as described.

When I found out I didn't want to fool with it, I mailed all the parts to the vendor who reassembled the unit and sent it back. All I had to do was press the assembled unit it back onto the stage.

I just didn't want to have to ship the entire stand in for a diaphragm repair. The iris diaphragm unit itself is just a few ounces. A cheap shipping fee.

What ever you do, just don't bend the blades or you will be buying a new unit instead of reassembly.

How other diaphragm assemblies mentioned above will fit on the Gemolite or other brands I don't know. I would think that would be manufacturer specific.


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PostPosted: Fri Aug 22, 2008 2:32 pm 
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JB is talking about an unmounted iris diaphram, whose outer diameter should be some standard size. After all, Meiji and GIA are not going to fabricate those specialized pieces themselves when it is easier to purchase them wholesale from a specialized manufacturer.


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