Why get two differencial parts parameters?

Hi!
I don't understand it why get different information. Please help me because it is not logical for me. Via parameter problem.
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Comments

  • edited September 2019
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    The developer of AutoTRAX DEX. 
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  • I read that but I don't understand. Why get two differencial informations. 
    The logical and simple me : diameter =1.4 
                                        hole diameter = 0.4
    so I not need playing what is the right diameter like : annual ring x2  and hole diameter. It is not logical, only my opinion.
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  • Annular ring is an extea information that is common use. It is to give the size left of the pad after drilling without having to calculate. It is because it is very important for manufacuring and reliability. Not needed but good to have directly. Often you design using annular ring size and not diameter. You set the hole and annular ring and let the diameter be what it will.
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  • I understand!
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  • The developer of AutoTRAX DEX. 
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  • Especially the first of Ilyas links shows the importance of not having a too smal annular ring. Smaller pads and holes increases need for precision and therefore cost. Down to a certain degree, almost every manufacturer have pretty good precision today so if your not in dire need for very compact boards the smallest but still no extra cost will be smaller than you really need.
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  • Thanks !
    I always learning!
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  • image
    The developer of AutoTRAX DEX. 
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