Yes! We have no metric drill bits.

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.

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Related essays:

Without Metric Threads We’re Screwed

A Hole in The Screw Head