# Measuring drill bits



## Vavet (Jul 10, 2020)

I'm organizing a laboratory for an engineering team. There is a community toolbox with a nice collection and organization system of drill bits - fractional, wire gauge, and letter sizes. I am not at all optimistic that users have always returned drill bits to the appropriate drawer. 
I essentially have a large pile of drill bits and I need to measure them to put them in the appropriate slot. 
The problem is that the difference in numbers we are looking at is tiny. There are fifteen examples in which the difference between two adjacent sizes is 0.001" or less. The smallest difference is 0.000125" (K to 9/32). 

What is a good way to measure these so that I can be certain to get each bit back in the correct place? Seems like a micrometer or caliper won't be accurate enough, especially in my somewhat inexperienced hands. 

My plan is to sort them and then color code them to make this problem easier to handle in the future.


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## benmychree (Jul 10, 2020)

Buy a set of good quality drill gages, like Starrett.  If there is only .001 difference between sizes, what is the difference?  A drill bit is not a precision tool.


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## Tozguy (Jul 10, 2020)

What about using a magnifying glass to read the ones that have the size shown. Otherwise a tenths digital micrometer should do the trick, even in your hands


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## Asm109 (Jul 10, 2020)

Just remember to measure at the cutting edge, not the solid diameter at the base.  Why? Because they are tapered smaller by a couple thou as you go to the back end.
Until you get to the really small bits, they have a size stamped or electro etched on the bit.  And as others have said if you can't tell what size it is with a micrometer, it doesn't matter which bin you drop it in.  Drilled hole tolerances are +.003 -0 at best.


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