Metric System Conversion

Over 27 years ago I participated in a year in a graduate education program for "metric education" and learned a great deal about the history of measurement systems throughout the world and throughout history. These courses were designed to teach a group of teachers to become mentors for other teachers on how to teach metrics in virtually all subject areas of the curriculum. It looked like, the United States was about to take the serious step toward full conversion to the metric system. Now, after all those years, we are still using a mix of measurement systems and there are many reasons for not full conversion.

Some people think that the metric system is more accurate and this is technically not correct. Virtually any system can be accurate to either the degree it was originally meant to be accurate or can be adjusted to be as accurate as needed for any particular situation. The main points are that the metric system, which works using base ten math it has easier conversion of units and the other main point is that products produced around the world have universal tools for repair and use.

We have a rich jumble of measurement systems. The history of how they were developed is extremely interesting. Many historical methods of measure were filled with "potential" and "real" opportunity for error, but some of this is understandable. For example: When you purchase a 2 x 4 it does not measure 2 x 4 inches and it is definitely still not sold in the United States in metric units (sometimes both English and Metric Units are displayed). Originally mills did come closer to the full 2 x 4 inch measurement, but because mills were not like the computer controlled mills of today, they were not able to produce exact 2 x 4 's with every cut of the lumber. Mills were allowed to produce all lumber with a range of errors. Older homes may still have 2 x 4's that are pretty close to a full 2 x 4 inch measure. Today, with computer driven wood mills, the accuracy is extremely precise, but actually producing a full 2 x 4 inch board, would use more lumber and would not work well in homes now constructed with the smaller 2 x 4. This illustrates how some inaccuracy can become part of a system and remain part of a system. A degree of inaccuracy was and still is acceptable in a wide range of products.

In a manner of speaking "digital measurement" is less accurate than "analog measurement" because analog measurement is a continuously changing measure over a complete range where digital measurement is a measure at specific points along a range. At first when I worked with the F-4 phantom jet weapons control system analog systems of measure were used to determine the distance from one jet to the enemy jet for targeting, but as digital systems began to be used in such systems it became clear that continuous measurement was not required. If the digital measure to the enemy jet was accurate to a distance of for example of even a few feet, it would not matter. The missiles used would detonate automatically when the missile had reached the point at which it was closest to the enemy jet and that distance started to increase. Because we had made such strides in the development of digital computers, it was natural to convert to digital systems.

Digital systems work on the base two system of measure, so the development of the computer may even be partly responsible for the slowed conversion to the metric system. I would not suggest that we all learn to do base two math however.

If industry in the United States wants to sell products in other countries, those countries often require measurements for those products, tools for repair of those products and parts for those products be provided in metric units. This creates standardization in one direction. Products provided to the United States that are produced in metric standardized countries is most likely to be provided to the United States with metric standardization.

The problem is largely with products produced inside the United States where retooling factories into metric production could be extremely expensive and as a result most factories resisted until their machinery simply broke down beyond repair and had to be totally replaced. This meant that conversion in the United States to the metric system would take much more time than anticipated. Even the cost of changing road signs throughout the United States is so high, that resistance to change can be understood simply from a cost perspective.

There are times when special tools are required to repair, remove, or install some products. At times this is done, to force those working in certain industries to purchase these special tools, but in some cases this could be related to safety or to reduce theft. For example: If a special screw is used before you can open a "missile", then you have made it more difficult to disarm if you do not have the required tools. In everyday life: If a special screw is required to put a latch on a bathroom door in a restaurant, then it is less likely someone might attempt to steal this hardware. Technicians have many specialized tools that may not be in metric units.

It is unlikely that the metric system will ever be used in every situation, but as industries are pressured to broaden their sales throughout the world it is likely that we will continue this long road of change.