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Measuring and Layout |
Proper measurement and layout is key to precision in the home shop. Here are my notes on some tips and techniques to help.
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Bolt Circles |
I have had particular trouble accurately measuring bolt circles. An accurate method I discovered involves measuring the Chords:
Measuring a Chord
The two drill bits are used to provide a reference that is easily accessed with your calipers. Be sure the accurately fit the holes! The greatest accuracy also comes of using the longest possible chord, so don't just pick two adjacent holes. Here is the clever formula used to determine the bolt circle diameter:
D = C / sin(180 M / N)
D: Bolt Circle Diameter
C: Measured Chord
M: Number of Holes Between The Two Measured Holes
N: Total Number of Holes in the Bolt Circle
For this example M=2 and N=5
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Dovetails |
Dovetails are another slippery one to measure. The two cylinder method is the preferred approach:
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Laser Metrology: How NASA Measures Things! |
See my special page on laser metrology.
Measuring Plate Flatness With A Laser Level...