Drill bits ?

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Krudwig

Krudwig

Member
Joined
Dec 11, 2013
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165
Location
DEQueen, AR
I have a question about drill bits sizes. There are metric sizes like the standard 7 mm for slimline pens which was my first pen and then I bought a 10 mm for the classics I made. Then there are standard sizes or fractions like 23/64 and 25/64 which I'm used to buying in fact you can't even buy a metric size drill bit in this one pony town, so I have to order those, but my question is about lettered bits like U size or other lettered size bits. Are these bits neither metric or fractions or are they lettered just so people don't have to know a metric size or a fraction or are they a size that is somewhere between these two? I see people will advertise a kit uses or takes a letter sized drill bit so I am just trying to get it straight and I know there are people here that are eager to help straighten it out! Thanks
 
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Do a search for drill bit size chart online. Like many people have partial and full drill bit indexes. With my chart and digital calipers can get pretty close to what actually need.
 
Krudwig said:
I have a question about drill bits sizes. There are metric sizes like the standard 7 mm for slimline pens which was my first pen and then I bought a 10 mm for the classics I made. Then there are standard sizes or fractions like 23/64 and 25/64 which I'm used to buying in fact you can't even buy a metric size drill bit in this one pony town, so I have to order those, but my question is about lettered bits like U size or other lettered size bits. Are these bits neither metric or fractions or are they lettered just so people don't have to know a metric size or a fraction or are they a size that is somewhere between these two? I see people will advertise a kit uses or takes a letter sized drill bit so I am just trying to get it straight and I know there are people here that are eager to help straighten it out! Thanks
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We have three sizes--- fractional that usually increase in size from 1/64th upward in 1/64th inch increments. Number and letter which are gauge;

Nmber sizes begin with 1 (which is the largest) at .2280 inch and decrease in size to #80 which is .0135 inch. the number sizes decrease by a thousandths, but the exact difference between sizes varies from .001 to .007 inch.

Letter sizes take up where numbers end and increase in size from A at .2340 inch to Z which is .4130 inch. They increase by from .004 to .010 inch

Metric sets usually start at 1mm and run up from there usually at about 1mm or 0.5mm increments. Sizes smaller than 1mm are available.

Fractional and number/letter gauge are used mostly in the USA and the rest of the world use mostly metric.
 
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Hey Larry....There's an app for that! :biggrin:

If you have a smart phone there are several apps out, I have one called iEngineer and it has a drill bit chart that is very helpful
 
.good ole Harbor Freight has a Standard, Lettered and Numbered drill bit set for around $30.00 if you a 25% coupon. Not the best quality but they work. Good luck and be well.....Jan
 
Hey Guys, Thanks for the education. Being really just a finish carpenter we really don't deal with anything smaller than 32nd or 64th of an inch. My uncle was a machinest at the railroad and said a train wheel is turned to within just a very few thousands of an inch tollerance which is very little for something so big, but if he did carpentry work he thought a 32nd was just too much give, it was like we were doing rough carpentry with a chainsaw or something. But thanks everybody for givining me the good ideals and a better understanding of drill bits and thanks Leroy for being so complete it does make sense to me now. I do have a smart phone and will get the app and hte harbor fraight drill index is something ill probably get next trip to Texerkana. Again thanks everybody!
 
You might want to consider your drill bit purchases. You may just want to invest in the sizes you need, and in a better quality, there are not that many. (from the man that has more than he can count) The HF sets in my experience were a poor choice. From bits that were the same size as one next to it to soft metal that dulled easily and bent under pressure.
 
If money is an issue, my suggestion would be to buy only the bits you need now AND buy yourself a drill doctor so you are always working with sharp bits. The worlds best bit is worthless if it is dull. The worlds cheapest bit may do the job if you keep it sharp.

I like HSS drills and I try to buy ones made in the USA, Europe (UK, Germany / Poland) or Japan. I avoid chinese drill bits unless I don't have any other choice (and there is always another choice).

Ed
 
I'm kind of a fan of the big HF box o'bits. It allows you to have just the right size bit for occasional use. Those bit sizes that I end up using often have been upgraded over the years.

I disagree that there are only a few bit sizes that we use, I bet that there are close to twenty.
 
mredburn said:
You might want to consider your drill bit purchases. You may just want to invest in the sizes you need, and in a better quality, there are not that many. (from the man that has more than he can count) The HF sets in my experience were a poor choice. From bits that were the same size as one next to it to soft metal that dulled easily and bent under pressure.
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On the other hand - I have a full set of fractional and wire gauge size bits that pretty well lets me drill any size I want - when I want. Actually I have two sets, one is about 20 years or so old and is mostly still intact with a few bits having been replaced. The other I got along with an 18V drill and it is a set of good bits. I also have a smaller set of fractional hex end quick change bits. I don't use most of them very much mostly a little smaller bit than the screws i'm using in wood pretty much #6,8,10 &12 wood screws. I tend to screw & glue much of the time - and always drill pilot holes when using wood screws to avoid splitting
 
sbell111 said:
I'm kind of a fan of the big HF box o'bits. It allows you to have just the right size bit for occasional use. Those bit sizes that I end up using often have been upgraded over the years.

I disagree that there are only a few bit sizes that we use, I bet that there are close to twenty.
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In total, I believe you're right, but you'd need full sets of both metric and US sizes to get them all. I think though if you have a full set of wire gauge bits you can get pretty close to all of them with just that set.
 
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Smitty37 said:
sbell111 said:
I'm kind of a fan of the big HF box o'bits. It allows you to have just the right size bit for occasional use. Those bit sizes that I end up using often have been upgraded over the years.

I disagree that there are only a few bit sizes that we use, I bet that there are close to twenty.
Click to expand...
In total, I believe you're right, but you'd need full sets of both metric and US sizes to get them all. I think though if you have a full set of wire gauge bits you can get pretty close to all of them with just that set.
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I have the 115 piece set from HF (with some replacements) plus a metric index box with about half a dozen metric bits that I have found myself needing and some oversized ones that have come in handy. In general, I have the bit that I need and the ones nearby.
 
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