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05-27-2014, 09:35 AM   #16
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QuoteOriginally posted by tim60 Quote
I could not believe how they could make thread align so well over such a huge amount of production.
Those have been my thoughts as well.


Steve

05-27-2014, 10:05 AM   #17
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QuoteOriginally posted by tim60 Quote
I could not believe how they could make thread align so well over such a huge amount of production.
My understanding is that the design of threads on components is guided by mathematically-based principles, well-established equations, and standards, which have existed for a long time. The other major elements in the manufacture of precise threaded components is the production tooling itself, and the quality-control processes.

Takumar lenses, for example, are well known for their mechanical precision, and the OEM Pentax K adapter is also well made. I'm not surprised they mate exceptionally well and consistently. They're 'Pentax' after all!

- Craig
05-27-2014, 01:24 PM   #18
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I just did some mental arithmetic. The accuracy of positioning of my worst takumar on my OEM adapter suggest an axial positioning error in the thread start of about 25-30 microns. Worst deviates by about 30*. The metal working machinery must have been pristinely clean to enable tool positioning of that accuracy over so much production. And this is on a dimension that does not affect performance, only aesthetic experience of the user.
05-27-2014, 02:19 PM   #19
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QuoteOriginally posted by tim60 Quote
I just did some mental arithmetic. The accuracy of positioning of my worst takumar on my OEM adapter suggest an axial positioning error in the thread start of about 25-30 microns. Worst deviates by about 30*. The metal working machinery must have been pristinely clean to enable tool positioning of that accuracy over so much production. And this is on a dimension that does not affect performance, only aesthetic experience of the user.
The old auto aperture pins had to line up with the lever on the body...

05-27-2014, 06:16 PM   #20
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QuoteOriginally posted by vonBaloney Quote
The old auto aperture pins had to line up with the lever on the body...
The actuator in the body* is a flip-up plate describing about 60 degrees of arc.


Steve

* At least the M42 bodies on my shelf...
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