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Feature of Size (FOS) 2

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SpaciouS

Mechanical
Joined
Jun 3, 2011
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69
Location
US
As I understand it, a FOS must satisfy all of the following:
[ul]
[li]Contains opposing elements or surfaces (regular or irregular shapes).[/li]
[li]Can be used to establish an axis, median plane, or a center point.[/li]
[li]Is associated with a size dimension.[/li]
[/ul]

Then you hear about the "Caliper Rule", where you should be able to measure or pick-up the feature with a pair of calipers (or 2 fingers).

My question is, what if, for example, you have a lens cell (for opto-mechanical design) with 3 tangential flexures 120 degrees apart about a common axis, and on those flexures you have raised pads which interface with the glass lens. These pad surfaces are arced and between the 3 of them they essentially form a diameter. Doe this constitute as a FOS (internal)?

I say yes. Even though the elements or surfaces are not "opposed" and you could not measure or pick-up the feature with a pair of calipers, you could measure or pick-up the feature with an expanding pin. Would this fall into the "irregular FOS" category?


Thanks,
Sean
 
If I picture this correctly, my answer is yes - this is internal irregular FOS.
 
Season,

Yes thank you for that link. That's pretty much it...

Thanks,
Sean
 
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