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"b" Dimension in Mounting Hole |
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Batiskaff 
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Joined: 30 Apr 2018 Status: Offline Points: 65 |
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 Topic: "b" Dimension in Mounting HolePosted: 30 Dec 2020 at 6:05am |
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What does mean "b" dimension?
This is hole dimension that I want to get in MTG or this is diameter of screw that will be insert in MTG?  |
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Tom H
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Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718 |
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Posted: 30 Dec 2020 at 10:35am |
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For Plated Through-hole the "b" dimension is equal to the hole size.
For Non-Plated Through-hole the "b" dimension should be larger than the hole size. Probably the hole tolerance +/- 0.05 annular ring. If the hole is non-plated, you want the drill bit to go through FR4 material and not touch any copper to avoid copper slivers in the hole. |
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Batiskaff
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Posted: 30 Dec 2020 at 2:02pm |
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So, if i need the Plated Mounting Hole with loose fit of M3 screw i should add a bit to 3 mm. For example: b=3+0,5=3,5mm. After that i should enter 3,5mm in "b" field, will it be correct?
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Tom H
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Posted: 30 Dec 2020 at 2:16pm |
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A Plated Through Mounting Hole the b = Hole Size.
b > than Hole size for Non-plated holes. There is a Hole Size Calculator in the main toolbar "Tool Box". |
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