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Yes! We have no metric drill bits.

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By The Metric Maven

My Engineering career started with a number of years working in aerospace. This was where I learned that outside of the interior of a  computer program, metric units are unwelcome. Early on, I tried to argue against this, but the entire system is structured to maintain the use of decimal barleycorn inches and a feral unit called “the mil.” I was worn down after a prolonged period, and accepted the situation.  Following the disappearance of The Berlin Wall, I began working for a large consumer electronics manufacturer. There I was able to  use metric measures with very little push-back. I was later told that they had been using inches for years, but after they were purchased by a French company, the French were horrified and mandated metric. I’m sure the company would have continued its merry way with Ye Olde English if the new owners had not stopped the practice.

I had thus far worked for large companies, but then I found myself with an opportunity to work for a small start-up with about 10 employees or so. It was heady, intense and rewarding. One had to contribute in ways that were unthinkable in a large organization. The most notable difference was that this small company used Ye Old English fasteners and dimensions. I wasn’t happy about that fact, but I had been ground down for so many years that I lived with it. The start-up was purchased by a medium sized company which had a policy that one could use metric, but had to maintain it throughout the design. I was elated. I immediately switched over to mm. What I didn’t realize at the time, was that I really wasn’t using metric, but pigfish-metric. Everything else, pressure tests, pull tests, temperature tests, fasteners and so on were all Olde English. In reality I was only using millimeters, and not The Metric System (i.e. SI). Looking back I feel I was unknowingly put in the position of the accountant in a Monty Python sketch who wanted to be a lion tamer, and when asked what his qualifications were indicated he had purchased a lion tamer’s hat. This is the strange cognitive dissonance of measurement which is thrust upon technical workers in the US.

When we needed parts, we went to the local hardware store and purchased them. We did what we could to save time, and waiting for a large technical supplier to ship us parts, was only utilized when there was no other option. The default was to purchase Ye Olde English fasteners and such at a hardware store–because they were available.

When the avalanche of off shoring whisked me into unemployment, I managed to begin making a living as a Consulting Engineer. I vowed that I would uncompromisingly use metric, and only metric, when doing my designs. This insistence has caused a number of serious and humorous encounters with my clients over the years. I also did the one thing which US engineers seem to find unnecessary–I sought out advice, and found it in the form of Pat Naughtin and his work. I’ve been very pleased with the changes I’ve made with his guidance.

Recently, a client was interested in a design which is (thankfully) all in metric. I had  designed a printed circuit board (PCB) which was to be “heat staked” into a plastic piece. I also had the plastic 3D printed prototype in my possession to which the PCB would be attached. My prototype PCB needed to have its pilot holes drilled to a larger diameter, so they would fit the heat stakes. Because the PCB I designed is an electromagnetic device, the tolerance has to be tight. For the given heat stake diameter, I needed a 2.3 mm diameter drill bit. There was just one problem. I had purchased an inexpensive set of metric drill bits long ago with 2.0 and 2.5 mm bits, but I needed a 2.3 mm. Larger more expensive sets of drill bits do include 2.3 mm, but I had not spent the money. I looked online and indeed I could order a single 2.3 mm bit, but it would be a small cost for the bit, and a large cost for shipping, if I wanted it next day or by two day. I thought, well, it’s a long shot, but perhaps my hardware store has a 2.3 mm. It’s a bit uncommon, but I could luck-out.

I went to a nearby ACE  Hardware store. A fellow asked what I needed. I told him drill bits. We were right near them and walked up to a large wall of drill bits.

“It’s a bit uncommon, but do you have a 2.3 mm drill bit?” I inquired.

The fellow’s countenance became one of slight contemplation. Then he said “I’m sorry we don’t carry any metric drill bits, we only have standard.”

“No” I replied, “the label of standard is a misnomer. Ninety-five percent of the world’s population do not use fractional Olde English drill bits.”

“Well, that’s all we have.”

I then found myself searching through my tool box in exile which has Ye Olde English fractional drill bits. Inside the drill index I saw that the 3/32″ drill bit  had a number below it indicating it’s 2.38 mm. It uses a comma decimal delimiter 2,38 mm apparently so Americans would be sure to know it’s furin’ and not consistent with America, mom, and apple pie.  I pondered and pondered if 400 µm  40 µm extra per side would matter. I finally decided after a small amount of analysis to try it, and it did work.

“From My ‘Standard’ Set of Drill Bits”

When I later related this story to Sven, I suddenly realized that yet again I had accepted something singular as “normal.” No metric drill bits? They sell metric machine screws, but not metric nylon machine screws (I use these a lot in my work). What this implied to me was that if you have  something which is already metric, then we have some parts, but if you want to build in metric, this is not the place. As small businesses and start-ups are generally dependent on local hardware stores for quick turnaround on prototypes, this produces a bias toward Ye Olde English tools, fasteners and such. Should a business grow to the point where it has international dealings, it will be using “standard” parts, which are completely incompatible with the rest of the world. This is baked into the US cake because we’ve never had a government led metric switchover like Australia. We just have a government which enforces the use of Ye Olde English units.

Was this situation singular, or is finding a metric drill bit as difficult as finding an engineer who still uses a slide rule? I decided to do a bit of field work. Here is a short list of what I found:

Ace Hardware — No Metric Drill Bits “We only carry standard”

Harbor Freight — No Metric Drill Bits

Home Depot — No Metric Drill Bits “I don’t know why that is.”

Lowes — No Metric Drill Bits “We don’t carry them and I don’t think anyone else does either.”

Sears — No Metric Drill Bits  MM: “Do you have any metric drill bits?” Sears Assistant: “No Sir, they are all SAE.”

The woman who helped me at Lowes mentioned that they had a few metric screws, but not much else. Others had come into the store and commented they had more metric fasteners than anyone else, and they don’t have much. I’ve not found a hardware store that sells metric nylon machine screws, and when I asked, she indicated they didn’t have any.

The fellow who works at Sears indicated that the bits were all SAE. Well SAE stands for Society of Automobile Engineers, and I’m fairly sure that except for a few parts which help to camouflage the fact that Automobiles are all designed in metric, makes this statement almost nonsensical—except in the US.

My informal sampling of local hardware stores confirms a point which I’ve made in the past. There is an invisible metric embargo in the US. It also shows that Dr. Gallagher’s assertion that we can use metric if we want to, demonstrates that he doesn’t get out of the NIST building much. It is possible to obtain metric drill bits and some metric tools from industrial houses such as McMaster Carr or MSC, but this must be done by post, and one cannot go down to a local store.  Other metric tools, such as mm only rulers, tape measures, squares and so on are simply not available, even at these industrial suppliers. The answer at all the hardware stores was Yes! We have no metric drill bits.

We’ve been hearing from metric advocates, for many number of years, that the US is 50% metric. What this actually means is not clear or well defined. This brings me to my final point, that the assertion which claims the US is 50% metric appears to be unfounded and a non-statistic. It has been pulled from the thin air of wishful thinking. Small start-ups use what is readily obtainable, and anything that takes time to obtain, is neglected, unless there is simply no other option. People will not go on a “metric snipe hunt” just to possibly obtain metric fasteners, tools, metals, sandpaper and other items used in the fabrication of a product. It’s time we faced up to just how large the problem is in the US,  and quit waiting for some imaginary “Darwinian pressure” to bring metric to the US. We have been waiting for 150 years. Continuing to wait for metric tools to appear in US hardware stores of their own volition  is a fool’s errand, and we in the US look more and more foolish every day.

Related essays:

Without Metric Threads We’re Screwed

A Hole in The Screw Head

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.


The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.


The third book is not of direct importance to metric education. It is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.

They’re Dead Jim

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By The Metric Maven

Bulldog Edition

When I think about the group of non-metric units used in this country, it reminds me of a Twilight Zone episode, The Hitchhiker. A young woman keeps encountering a hitchhiker over and over and finally becomes convinced he is trying to kill her. She attempts to run him over,  but fails. She drives without rest and tries to stop only when absolutely necessary, but each time she stops, there is the man, hitchhiking. After a phone call, the woman realizes that the man is not trying to kill her, but she is already dead. He is the personification of death, patiently waiting for her to realize that she had been dead all along.

In my metaphor, the woman is the set of Olde English Units to which we cling. The terrifying hitchhiker is the metric system, patiently waiting for the set of units to realize it is dead. One way to see that the set of Olde English Units we use is dead, is to realize that they have not changed in the last 150 years (actually for centuries in some cases). The metric system has evolved and changed. There have been a few incarnations of metric. The British, who in my view were trying to hang on to a metric system which is as similar to Imperial as possible, created the cgs or centimeter-gram-second system. Long time readers know what I think about using a centimeter, period, let alone using it as the basis for a measurement system. It’s a pseudo-inch system. There was The Metric Technical System (mts) which was based on force rather than mass. Herbert Klein in The Science of Measurement relates:

Systems that are based on force or gravitational units rather than mass units must be supplemented by a separate unit of mass designed to go with the basic unit of weight. In the Metric Technical System, this added mass unit is the metric slug, or hyl (9.80665 kgm)  (page 205)

To confuse matters further there was also another mts, the meter-tonne-second system, which thankfully is now but a historical curiosity. These systems seem to have invoked a strange version of The Implied Precision Fallacy. The idea was that mts is for industry and cgs is for laboratory work, but thankfully SI became the system for all to use—well except in one country.

The mks or meter-kilogram-second system became popular and shows that nature can sometimes produce miracles, a reasonably elegant system from a committee. Even as all the discussion was raging about the metric system and its constituent units, what to add, and what to remove, there was no parallel discussion for the Olde English Units used by the US. Apparently the Anglo-Saxons of the Middle Ages had given us the one and true system of units for all time, perfect and sublime, and no others were ever to be needed. The world it reflects is static. There is one problem with this notion however, the world has changed in ways the 8th and 14th centuries could never have contemplated. First there was the discovery of electricity. This precipitated Mary Shelley into writing the first Science Fiction novel, Frankenstein, which was based on Galvani’s experiments. The discovery of the relationship between electricity and magnetism was a startling and unexpected connection.  This fusion, electromagnetism, was theoretically described by James Clerk Maxwell and was commercialized by George Westinghouse. In 1893, the World’s Colombian Exposition in Chicago placed on display  the wonders of Westinghouse electric lighting for all to see. Nearby, however, another gathering of much greater importance occurred, which is generally forgotten. It is described by Hallock and Wade (The Evolution of Weights and Measures 1906 pg 208):

In 1893 in connection with the World’s Colombian Exposition at Chicago, an International Congress of Electricians was held, and a Chamber of Delegates, composed of officials appointed by various governments, proceeded to define and name the various electrical units.

The US Congress passed an Act on July 12, 1894 which defined and established the units of electrical measure for the United States. These consisted of those agreed upon at the Chicago congress of Electrical Engineers in 1893, which displaced the definition of the ohm which was in use by Great Britain. According to Hallock and Wade in The Evolution of Weights and Measures 1906 pg 207:

At a meeting held in 1884 an international commission decided the length of the column of mercury for the standard ohm, and the legal ohm was defined as the resistance of a column of mercury  of one square millimeter section of 106 centimeters in length at a temperature of melting ice.

This did not win out however when:

…Professor Henry A. Rowland in America and Lord Rayleigh in England, carried on further investigations to evaluate the true ohm, with the result that the length of the mercury column was found to be nearly 106.3 centimeters, which accordingly was adopted by the British Association Committee in 1892, together with the definition of the column in length and mass, rather than length and cross-section.

Well, as I’ve stated in many blogs, they should have used millimeters. The length would have been 1060 mm and changed to 1063 mm with nice round numbers, just like the Australian construction industry.

The ohm, ampere, volt, coulomb, farad, joule, watt, and the unit of inductance, named the henry, after Joseph Henry, were all defined in Chicago. In case you are uncertain of its location, Chicago, is in the United States, near Berwyn. Yes–Berwyn. There were no US representatives trying to define alternative “US Customary” equivalents of the electrical units. No argument for the inclusion of barleycorns, inches or yards in the electrical definitions were contemplated, they were all metric. Electricity,  perhaps the most important discovery since fire, is not described in any way by US Olde English Units. The US Olde English (USOE) units are stagnant and have been since the 14th century. “They’re dead Jim.”  The ohm is no longer defined as it was in the 19th century, using columns of mercury. It was redefined in 1990 using the Quantum Hall Effect. It continues to be improved and changes with the times. Metric units are living units. Olde English Units are Night of the Living Dead units.

Those who misguidedly try to resist the use of metric units in the US, have created a weights and measurements apartheid. There is one set of medieval pre-scientific units for the masses, which separate them from the creations of modern Engineering and Science, and one set of measurements for those educated beyond High School in a technical discipline.

Strangely Americans don’t see this as insulting, but in my view they should. They are locked into a set of units which creates a barrier between the public and the important scientific information needed to make critical public policy decisions. If one is forced to use US Olde English units, one never develops the “feel”  or comfort with metric units, which 95% of the world’s population has when evaluating scientific results. US Olde English Units are so anachronistic, and arrested they cannot, and do not, offer a description of electricity. How can they but act as a barrier between Americans and all the Engineering and Scientific discoveries since 1893? They are all in metric units. Some see this as “freedom,” I see it as state sponsored ignorance, imposed on US citizens, and apologized for by quislings. Herbert Klein, author of The Science of Measurement (page 24) makes this statement, which should have an asterisk, but does not. I have taken the liberty to add one:

Moreover, the tools and techniques of measurement provide the most useful bridge between the everyday world of the layman and of the specialists in science.*

* Except in the United States of America.

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.


The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.


The third book is not of direct importance to metric education. It is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.