Identifying random drill bits

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I'm in the final stages of a major shop re-organization. Over the years I have picked up several hundred loose drill bits. Some are jobber length, some screw machine length. Some are bright metal, some black oxide. I don't quite know what to do with all of them. All are new and sharp and should cut well.

I plan to buy a handful of drill indexes to store them, but how do I know for sure what size each bit is supposed to be? Many of the shanks are unmarked, and even some of those which are marked are quite difficult to read, even with magnification. With a decent set of calipers I can measure the shanks, but that doesn't tell you all you need to know. Or does it?

Suppose I have five bits which measure from .166" - .172". How does one tell #19, #18, #17, and 11/64ths apart? I know that all bits cut holes slightly larger than the shank diameters. Does the shank diameter determine the designation of the bit, or is that determined by the actual size of the hole drilled?

I have a feeling there is a simple answer that is just waiting for me to discover it... Or maybe I'm way overthinking this.

Thanks in advance,
Harry
 
There are inexpensive drill bit sizing gauges available to get the ones that you can't read the shank markings. I have a drawer full of bits that I need to do the same thing with....I bought the gauge, now I just need to get the motivation.

FastPauly

drill-bit-size-gauge.jpg

drill-bit-size-gauge.jpg
 
Thanks FastPauly,

I even have one of the gauges. But it doesn't differentiate between bits whose shanks are a thousandth or two different in size.

Harry

FastPauly said:
There are inexpensive drill bit sizing gauges available to get the ones that you can't read the shank markings. I have a drawer full of bits that I need to do the same thing with....I bought the gauge, now I just need to get the motivation.

FastPauly

View attachment 42719
Click to expand...
 
I use a set of calipers. I turn the bit backwards till the calipers read straight across the flutes of the bit. Then I just look on my chart and thats it. Do not turn the bit in its cutting direction, it will dig in. Some people use the shank to measure but I do not trust that dimension.

"Billy G" :))
 
Thanks Billy G

Do you measure near the tip, or cutting end of the bit to get the most precise measurement? I know most bits are ground smaller as you approach the shank in order to give clearance.

Harry


Bill Gruby said:
I use a set of calipers. I turn the bit backwards till the calipers read straight across the flutes of the bit. Then I just look on my chart and thats it. Do not turn the bit in its cutting direction, it will dig in. Some people use the shank to measure but I do not trust that dimension.

"Billy G" :))
Click to expand...
 
As close to the tip as I can. As you go back on the bit it will get smaller. This is why I do not trust the shank method.

"Billy G"
 
the gauge is a fast way to sort them out in size. but then you will have to do like bill said and go through each pile to see if it is a fractional, letter or numbered bit by measuring.
steve
 
I have a tub that I throw all the bits that I've left laying around. Once or twice a year I go thru it and measure them to put them where they belong. The first pass thru them I use a strong magnifying glass to read the shank markings. After that using a micrometer near the tip is the only sure way to get an accurate measurement.
 
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