Lakhasly

We are often dealing with small numbers in this business. Tolerances, errors, deviations, uncertainties. Most of the values that are important to us in dimensional measurements are smaller than the thickness of your hair. These little numbers have multiple zeros after the decimal point, which makes speaking them difficult. You don't want to be saying something like 0.00005. Huh? To me, it all gets lost after hearing that second zero. In both inch and metric units, our industry has its own language. and some of it's a bit unwritten and unofficial, slaying terms. But those special terms can be very useful in everyday conversations. We've put together a technical bulletin on this topic. You can easily find it on the On Demand section of our website. In this episode, we're going to run through some examples of this language by looking at common measuring instruments, starting with this digital caliper. As shown on this digital display of this caliper, the resolution is 0.0005 inches. And even though I just said 0.0005 inches, I would never say that. In fact, just saying that now makes me a bit uncomfortable. Though the units are in inches, in practice we work in a world where the base unit is a thousandth of an inch. As shown in the second caliper. The tenths, hundredths, thousandths decimal place is one. And we would read this as one thousandth of an inch, or often simply one thou. This of course is slang, and I would never write thou down as a word, because it's not official. I would write this down, but say one thou. And we would probably not say inches, even though it is. So we say thou a lot. 1 thou, 2 thou, 15 thou, 123 thou. I could say 123 thousandths of an inch or 0.123 inches. But it's a lot quicker and more understandable to just say 123 thou. In some organizations, they even drop the thou and just say 123. it's understood that you are speaking in thousandths of an inch. In my world, in dimensional calibration, even a thou, as small as it is, is a big number. And we are often dealing with much smaller numbers. So how do we speak about numbers less than a thou? So looking back at this caliper, we see this number, and I'm not saying all those zeros again. When seeing this number, many people would simply say, half a thou. Another common way of reading this number is to say, five tenths. Where tenths is referring to this being the ten thousandth decimal place. Tenths, hundreds, thousands, ten thousandths. Or simply a tenth. This is useful slang. When our base is thousandths, then a tenth is a ten-thousandths. A tenth is very commonly spoken when using micrometers. This digital micrometer, for example, is reading three-tenths. Again, tenths, hundredths, thousandths, ten-thousandths, or simply three-tenths. on this micrometer, reads to a tenth. Just like the word thou, we never write the word tenth, but we do say it a lot. A tenth is a pretty small number. In many shops, that is about as small a number as you'll be dealing with. But in some cases, we need to go even smaller. But before we do that, let's look at the same caliper and micrometer examples, but this time, and metric units. This caliper reads out in millimeters, which are one thousandth of a meter. One really nice thing about the metric system are all the additional and legally official prefixes. You never say a thou of a meter, you just say millimeter. This caliper has a resolution of 0.01 millimeters. Which is fine to say, I suppose. But I really prefer to never say any leading zeros after the decimal point. And with the metric system, you never have to. When I see a number like this, I imagine moving the decimal place over three places. and using the next metric prefix. In this case, that's 10 micrometers or 10 microns, written with the metric prefix mu followed by the m for meter. When using metric units, we use microns a lot. We write the mu and we say micron. Now officially, there is no micron. It's a micrometer.