Number and wire drills

I would like to know the difference between # drills and wire drills? I have been told they are the same # is American and wire is British but the same size?

Notice no wire sizes. If there were wire size drills, they would be on this chart

Drill Size Chart (Inch)

jest a nova said:

I would like to know the difference between # drills and wire drills? I have been told they are the same # is American and wire is British but the same size?

Click to expand...

There are different standard sets of wire sizes. For instance there is the old Birmingham (England) gage and there is the Brown & Sharpe or American wire gage. Here is a summary: https://en.wikipedia.org/wiki/Wire_gauge

And here is info on the number and other series of drill bit sizes: https://en.wikipedia.org/wiki/Drill_bit_sizes#Number_drill_sizes Note this excerpt: "The gauge-to-diameter ratio is not defined by a formula, but is instead based on, but is not identical to, the Stubs Steel Wire Gauge which originated in Britain during the 19th century."

If you care, you can look up the diameter of a, for instance, no. 10 wire in the various American and British standard systems and see if any match the size of a no. 10 drill bit (.1935 inch).

Larry

This is what i am trying to work out. I need to replace a set of # drills 1 to 60 McMaster-Car list a wire gauge size set 1 to 80 and do not list the diameters of the drills only the 1 to 80 and they say they are the same as numbers. I need to sure before i order them. I have never heard of wire gauge drills?

I've always known them as number drills (and the larger ones as letter drills) and cannot remember ever hearing them called wire drills. My father also called them number drills, and that takes us back to the early decades of the twentieth century in England. Alas, I don't know what grandfather called them or we could go back to the nineteenth.

I have rooted round in my old books. My Tyzack (London) catalogue of about 1908 doesn't use either name but refers to them as gauge drills. Kempe's Engineer's year-book for 1929 doesn't mention them at all. Kempe for 1973 refers to Drill Gauge Number and Letter Drills.

As for wire gauges, take your pick from Birmingham, Standard, Imperial, Whitworth's, Warrington, Stubs Steel, Stubs Iron, Brown and Sharpe, Washburn and Moen...

Ah! Aha!!

I've just spotted a footnote in Kempe (1929) which says "The Stubs' Steel Wire Gauge is the one employed in measuring drawn steel wire or drill rod, of Stubs' make, and is also used by some makers of American drill rods". That being so, it seems more likely that 'wire drill' is an American usage.

George

Jest a Nova - you posted while I was composing. I'm quite sure that McMaster Carr are telling you the truth, and what they have is standard number drills. Go for it!

G.

jest a nova said:

This is what i am trying to work out. I need to replace a set of # drills 1 to 60 McMaster-Car list a wire gauge size set 1 to 80 and do not list the diameters of the drills only the 1 to 80 and they say they are the same as numbers. I need to sure before i order them. I have never heard of wire gauge drills?

Click to expand...

Are you able to cross reference with this table?


Drill Size Conversion Table

Deleted as my posted link is not working

johnoder said:

Notice no wire sizes. If there were wire size drills, they would be on this chart

Drill Size Chart (Inch)

Click to expand...

Cobalt Aircraft Drills - Wire Gauge Number Sizes , Nova® Pneumatic Drills, Carbide Cutting Tools


They also list wire size drills here in the UK.

Number Drills 1 - 80


Drill sizes to B&S chart.


Drill Bit to Wire Gauge Conversion Chart