 Posted: Thu Aug 16, 2018 1:47 pm Post subject: Meyer Domiplan and the stuck iris issue |
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Seele wrote:
Some months ago I got a bit tired of my Domiplans (five examples of various types) having their iris diaphragm either stuck open, or working with great reluctance, so I rolled up my sleeves and de-greased their iris diaphragm mechanisms, including the blades and driver rings. But two of them started showing the return of the fault last week, and the stiff focussing ring action on a couple of them induced me to investigate further.
The reason for the iris issue is due to the lighter compounds in the old helicoid grease evaporating, and then recondensed elsewhere, especially in the iris mechanism, causing the "oil on iris blades" condition and then some. So I figured that there had to be a lot of deteriorating grease in the works that keeps evaporating non-stop, so a complete service was in order.
After rebuilding all of them pretty much from the ground up, I can say with some certainty that most, if not all Domiplans, were over-greased at the factory: I was kept busy scooping out big chunks of grease from both the helicoid thread and the focussing ring thread, up to about half a teaspoonful of it from one lens. It was a bit of a job to clean and degrease the parts, and after careful application of new and more stable modern grease, just enough to do the job, they are all working well, and should not suffer from stuck iris again.
What I cannot figure out is why Meyer saw it acceptable to apply grease in such a cavalier fashion, but then I do not think getting a Domiplan rebuilt is an exceedingly complicated operation that is beyond my fellow correspondents' ability; it is something worth considering, I suppose. |
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