Inch or Metric?

A recent discussion on eng-tips.com has prompted some interesting replies.  The discussion revolves around one individual asking for advice to help in the battle to promote metric at his company, despite push-back from their machine shop, and a lack of concern about the issue from higher-ups who have taken a pragmatic cost related approach. I believe that the responses received may have surprized this individual.

There are some who point out that the cost of switching to metric must be justified and explained to management.  The problem here is that there IS a cost associated with switching from a shop based on inch tooling to a shop based on metric tooling.  Is there savings associated with the switch?  The benefits of switching units of measure are likely limited, unless they are dealing with much more complex issues.  Once a company has a system in place, it is generally not economical to switch it midstream.

Several made the point that if the company is already standardized to inch, then any individuals at that company should adjust their methods accordingly.  This is the same if a person accustomed to inch joins a company that has standardized to metric.

What I personally questioned was the rather strange idea that metric is somehow some sort of default when it comes to making the choice.   The universe doesn’t know the difference between an inch and a millimeter.  For us in the engineering field, it is easier to think in metric than in inch, but what are the real world advantages of one system or another?  Unit of measure is completely arbitrary.  One person who responded to the posting even pointed out the advantages of using hardware from both systems at the same time.

“But the rest of the world is using metric!”  Umm, really? That, by itself, is an arbitrary point.

A counter arbitrary point, the United States of America has the largest economy on the planet by almost 2-fold.  It doesn’t really matter what rest of world does because the U.S. is so big. It’s like saying that the 800lb gorilla in the room should wear jeans just because all the chimps in the room are wearing them.  Maybe the gorilla is happy with his corduroys instead.

To this, there was a response about how the world combined outweighed the U.S. economy, and that the US is not 100% inch.  My point at that time was simple, “…Americans might be surprized by the number of countries that ARE NOT 100% metric, many of which are in Europe. ”

I was surprized by the responses that comment provoked.  There is apparently much less standardization going on around that planet that we’ve been lead to believe by hardcore metric proponents here in the U.S.  I know about the imperial gallon, the pint, and oddities like the metric ton.  However, I didn’t expect responses from the international community stating that there are significant fields and regions where standardization is in the old traditional imperial system and not metric.

The more I explore this topic, the more I’m convinced that it really just doesn’t matter.  Once a choice for a company is made, then they should stick to it.  I’m also learning that some strong proponents of metric here in the U.S. have a tendency to assume metric has greater adoption than what is true in reality.

Author: fcsuper

As a drafter, mechanical designer and CAD engineer, I've been in the mechanical design field since 1991. For the first 8 years of my career, I was an AutoCAD professional. I utilized AutoLISP and many other AutoCAD customization features to streamline drafting activities for 6+ drafters and designers. I authored several custom functions, one of which was published in the March 1997 issue of Cadalyst Magazine. Since 1998, I've been used SolidWorks non-stop. I've worked to utilize the SolidWorks' user environment to simplify drafting and design activities for 20+ engineers. I've created this website to provide current information about SolidWorks from a variety of contributors. More recently, I am now employed by Dassault Systemes as SOLIDWORKS Sr. Product Definition Manager to improve drawing, annotation and MBD related areas.

9 thoughts on “Inch or Metric?”

  1. Funny you mention Gorilla. I think the word is Neanderthal.
    They where probably the first using the stones weight system to trade fish. My cave is 10ft and I have a 2″ flint.

    Bottom line. The metric system is a modern superior system. Simple as that.

    Regards: Homosapiens

  2. I think you willfully missed the point, Homosapiens. 🙂 Do you mean that it is superior because it’s based on being equal to 1,650,763.73 wavelengths of the orange-red emission line in the electromagnetic spectrum of the krypton-86 atom in a vacuum instead of the tip of a some king’s finger? Both are equally arbitrary.

    Oh, it’s better because it’s base 10 based? Yes, since we use base 10 numbers, that does make it easier. If you equate “easy” with “superior “, then sure. Yet, it’s still arbitrary. I could say that inch is superior because I don’t need to make measuring device to use it. I can just approximate it with my finger tip. That’s easy.

  3. One of the most interesting arguments against moving the US to a fully metric system is actually a solid engineering one. In the metric system, there is no direct correlation between mass and force. For example, force is measured in Newtons and mass is measured in kilograms, which leads to the equation 1 kg·m/s² in order to convert between the two. In the USC system, 1 pound(force)=1 pound(mass) which makes many calculations much easier. Distance is another matter, and one where the metric system certainly has advantages, however.

  4. Well US is still in the STONE AGE. There is NOT one real benefit for imperial as arrogance and ignorance pared with stupid Pride and poor education.
    OK It sounds hard . in fact this is the only way this can be described. USA is the only country on this Planet who is to stupid to learn or just to do metric. There is nothing to learn. 1 $ has 100 cent so what ? 1 meter has 100 cm it is such easy. But arroganz is in between.
    Ask an “american” engineer to tell you on 1/64 inch scale to give a 3 size bigger drill bit as 5/16 … will take a while
    ask a second grade in a development country to give you a drill bit on a 0.5 mm scale 3 size bigger than 6mm, it will be accomplished in 99.9% 10 times faster as from a American engineer. Here you are …. NO EDUCATION without logical numbers . Get your Job dine first before tell the rest of the planet what to do

  5. Richard, I believe your comment is unnecessarily hostile. Stone Age and education level have nothing to do with this since measurement systems are arbitary, as noted in the article. Also, the only statements here of anyone telling others what to do are found in your statement. Again, there are advantages to both systems and disadvantages. A particularly interesting example was posted by a fellow commenter above.
    Finally, the personal comment regarding pride is confusing. Imperial measurement was not invented by America. It is simply a system that was adopted based on European influences. Free market speaks volumes in determining adoption. The reason adoption has slowed here in the US is because it is simply unimportant for our needs to persue faster transition.

  6. The metric v imperial unit discussion is an interesting one and one I don’t believe you can find a clear answer to.
    In Australia we changed in the early/ mid ’70’s from a British Imperial system to a Metric system ( This followed from 1966 when we changed to decimal currency from British pound and pence) I was in a era of learning dual measurement. So I “speak” both units. Jump forward 40years, you would think that you would hear nothing but metric measurement. Nothing could be further from the truth. Sure kids coming out of school know nothing but metric, but once in the manufacturing world they need to adapt. Our plumbing industry refuses to change, so you still have 5/16 Flare fittings not M8

    We (where I work) buy some products out of Europe. Our plywood we buy is out of Italy. The sheet however are 2440 x 1220 ( the old 8′ x 4′). We also buy plywood locally which in most cases come out of Asia. These of are (hard metric) 2400 x 1200. Issues occurs when you are squeezing everything you can when CNC cutting.

    What we have ended up with is a “bastardisation” you will often hear “4” x 2″ x 3.6m”!! Or simply a “metrified” version of an imperial measurement 50.2mm not 2″

    If after 40years and a generation change we still can’t agree on what system to use then I would think internally in the US you would be fighting an uphill battle

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  8. Well US is still in the STONE AGE. There is NOT one real benefit for imperial as arrogance and ignorance pared with stupid Pride and poor education.

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