Micrometer: everything you need to know about this tool


Although it may seem like a unit of length, at micrometer we are referring to here is the instrument so named. It is also known as palmer gauge, and can be an indispensable tool for any a maker's workshop or for those passionate about DIY, since it allows to measure with great precision what other instruments cannot.

In this article you will learn a little more about what is it, what is it for, how it works, as well as the keys to choosing a good one for your future projects ...

What is a micrometer?

palmer gauge

El micrometer, or Palmer caliper, it is a very accurate measuring instrument. As its name suggests, it is used to measure objects of a very small size with great precision. Generally, they usually have a minimum error, being able to measure even up to hundredths (0,01 mm) or thousandths (0,001 mm) of a millimeter.

Its appearance will remind you a lot of a caliper or caliper conventional. In fact, the way it works is very similar. Use a screw with a graduated scale that will be used to determine the measurement. These devices touch the ends of the object to be measured, and looking at its scale you will obtain the result of the measurement. Of course, it has a minimum and a maximum, generally it is usually 0-25 mm, although there are some larger ones.


With industrializationEspecially during the Industrial Revolution, a great interest in measuring things very precisely began to flourish. The instruments used at that time, such as conventional gauges, or meters, were not enough.

A series of inventions of the past, such as the micrometer screw of William Gascoigne of 1640, they brought about an improvement for the vernier or vernier used in the calibers of the time. Astronomy was one of the first sectors where it would be applied, to measure distances precisely with a telescope.

Later would come other modifications and improvements for this type of instrument. Like the French Jean Laurent Palmer, who in 1848, built the first development of the handheld micrometer. The invention was exhibited in Paris in 1867, where it would attract the attention of Joseph Brown and Lucius Sharpe (of BRown & Sharpe), who began to manufacture it as a tool in bulk in 1868.

This event facilitated that the employees of the workshops could count on a much more precise tool than those they had previously. But it would not be until 1890, when the American businessman and inventor Laroy Sunderland Starrett updated the micrometer and patented a more current form of it. In addition, he founded the Starrett company, one of the largest manufacturers of measuring instruments today.

Parts of the micrometer

micrometer parts

In the image above you can see the most important parts of a Palmer caliper or micrometer. Are shares are:

1. Body : it is the metallic piece that constitutes the frame. It is created from a material that does not vary much with thermal changes, that is, with expansion and contraction, as this could cause the wrong measurements to be taken.
2. Stop: is the one that will determine the 0 of the measurement. It is important that it is made of a hard material, such as steel, to prevent wear and tear and may alter the measurement.
3. Spike: it is a mobile element that will determine the measurement of the micrometer. This will be the one that moves as you turn the screw until it makes contact with the part. That is, the distance between the top and the spike will be the measure. Likewise, it is also usually made of the same material as the top.
4. Fixing lever: allows you to block the movement of the spike to fix a measurement so that it does not move, even if you have removed the piece to measure.
5. Ratchet: It is a part that will limit the force exerted when performing the contact measurement. It can be easily adjusted.
6. Mobile drum: This is where the most accurate measurement scale is recorded, in tens of mm. Those with a vernier will also have another second scale for greater precision, even thousandths of a millimeter.
7. Fixed drum: is where the fixed scale is marked. Each line is one millimeter, and depending on where the fixed drum marks, that will be the measurement.

How the Palmer micrometer or caliper works

The micrometer has a simple principle. It is based on a screw to transform small displacements in a precise measure thanks to its scale. The user of this type of tool will be able to thread the screw until the measuring tips make contact with the surfaces of the object to be measured.

By looking at the markings on the graduated drum, the measurement can be determined. Additionally, many of these micrometers include a not me, which will allow a reading of measurements with fractions thanks to the incorporation of a smaller scale.

Of course, unlike the conventional caliper or caliper, Palmer's only measures outside diameters or lengths. You already know that the conventional gauge also has the ability to measure inside diameters, and even depths ... However, as you will see in the next section, there are some types that can solve this.


Several micrometer types. Depending on the way of reading, they can be:

  • Mechanics: they are totally manual, and the reading is done by interpreting a recorded scale.
  • digital: they are electronic, with an LCD screen where the reading is shown for greater ease.

They can also be divided into two according to the type of units employed:

  • Decimal system: use the SI units, that is, the metric system, with millimeters or submultiples of it.
  • Saxon system: use inches as a base.

According to what they measure, you can also come across micrometers like:

  • Standard: are those that measure lengths or diameters of the pieces.
  • Deep: they are a special type that has a support with two stops or a base that rest on the surface. While the spike comes out perpendicular to the base to touch the bottom and thus measure depths accurately.
  • Indoor: They are also modified with two contact pieces to measure distances or internal diameters accurately, such as the inside of a tube, etc.

There are also other ways to catalog them, but these are the most important.

Where to buy a micrometer


Si quieres buy a quality and accurate micrometer, here are some recommendations that may interest you:

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