Screw Micrometer: Parts, How to Read, Sample Problems

Basically, screw micrometers can be used to measure objects with an accuracy of up to 0.01 mm. Generally, this measuring tool is often used when someone wants to measure the size or length of a certain object.

If explained briefly, then the screw micrometer is a measuring instrument whose function is quite similar to a caliper. However, the level of accuracy of this measuring instrument will be much higher than the measuring instrument called the caliper.

Screw Micrometer Parts

This measuring instrument was first discovered in the 17th century by a scientist named William Gascoigne. In English, this measuring instrument is called the Micrometer Screw Gauge.

Later, this measuring tool will consist of several parts that have different functions from each other. Here are some of the parts it contains:

1. Frames

When you look at the shape of this measuring tool, you can definitely see the U-shaped part inside the tool. Well, this U-shaped part is called the frame name. Generally, this part will be made of heat-resistant metal.

In addition, the frame will also be made of metal which has a maximum thickness. That way, this section can minimize the effects of long expansion that can interfere with the measurement process while it is being carried out.

2. Anvil (Fixed Shaft)

The name anvil in this case comes from English, and in Indonesian itself is a fixed shaft. Unlike the previous section, the function of the fixed shaft itself is to hold the object being measured.

Later, this section can function to prevent objects from moving or shifting when they are about to or are being measured. In this way, the results of these measurements can be more accurate.

3. Spindle (Motion Shaft)

The location of the spindle in this measuring tool will also be close to the frame. Basically, this part can be moved towards a fixed shaft. Because, this part is made of metal cylinder, so it can be moved freely whether it's back and forth or away.

4. Lock Nut

This section will be located right next to the spindle section. Basically, this section will be useful for holding the motion shaft from moving when the object measurement process is being carried out. So, this part is also often referred to as a lock in it.

5. Sleeve

This section is made of metal rods and is located on the main scale of measurement, which in this case uses mm. Later, this section will be in the form of a circle and is useful for showing the exact scale of measurement.

So, this measuring instrument will have a dual scale in it, which includes the main scale and the nonius scale.

6. Thimble

The thimble size will be larger than the sleeve on this measuring tool. For the location itself will be next to the sleeve. This section can be moved by the user himself. Meanwhile, this section will serve as a place for the nonius scale to be placed.

7. Ratchet

To drive the motion shaft part, the ratchet part will be needed. This part can later tighten the motion shaft when it touches the object being measured. For how it works itself is to rotate it clockwise until you hear a "Tick" sound.

So that you can be more sure that the end of the motion shaft is perfectly attached to the object, you can rotate this part 2-3 times.

Read: Vernier calipers

Types of Screw Micrometers

Apart from having different parts, this measuring instrument will also be divided into certain types, which include:

1. Manual Screw Micrometer

You must have encountered this type of measuring instrument in everyday life. Because, with a very affordable price, making this measuring tool more often used by most people. As the name implies, how to read measurements from this tool is still using the manual method.

2. Digital Screw Micrometer

To read measurements using this tool, you don't need to do the manual method as before, because the results will be immediately visible on the available screens. Although the price is more expensive, this measuring tool can minimize the risk of calculation errors.

3. Outside Micrometer

Basically, this type of micrometer will be used to measure the outside diameter of a workpiece. For those of you who often measure objects such as wire, block objects, or layers of certain objects, this tool can be the most appropriate choice.

4. Inner Micrometer

Very inversely proportional to the external micrometer, for this type of micrometer will be useful as a means of measuring the diameter of a particular hole. Later, this measuring tool can be used to measure a diameter in a hole in certain objects, for example the depth of a pipe.

5. Depth Micrometer

If you want to measure the depth and height in a certain object, then this depth micrometer can be the most appropriate measuring tool.

The difference between a depth micrometer and a deep micrometer is that this measuring instrument can be used to measure the depth of a hole in more detail. This is different from the function of the inner micrometer which can only measure the diameter.

Read: Hydrostatic Pressure

How to Use a Screw Micrometer

There are certain ways that you can use this measuring tool, and some of those ways are:

• First of all, clamp the object to be measured on the jaw of this measuring tool.
• After that, rotate the thimble and ratchet until the object or object is completely clamped.
• If you have, turn the lock on the lock nut, so that objects and players cannot move anymore.
• Done, now you only need to read the measurement results on the main scale and the nonius scale.

Read: Ohm's Law

How to Read a Screw Micrometer

In addition to having its own way of using it, this tool will also have a certain way to read the measurement results, which include:

• Note the location of the scale line at the top of the sleeve. In this case, we will give an example in the figure of 5 mm.
• After that, also pay attention to the scale line at the bottom, which is 0.5 mm.
• Then note the value in the nonius scale on the thimble, which in this case is 28 mm.
• Multiply that value by the formula 28 x 0.01 mm = 0.28 mm.
• To end this process, add up the three measurements, which are 5 mm + 0.5 mm + 0.28 mm = 5.78 mm.

Read: Reaction rate

Screw Micrometer Function

Although in the previous few paragraphs we have discussed the function of this measuring instrument itself, but you still have to recognize its functions well, namely:

• Measuring the thickness of the workpiece that has a very large level of thinness, for example steel plate.
• Measure the outside diameter of small objects, such as wires and cables.
• Take measurements on the diameter of the holes of small and thin objects.
• Measuring the depth of a hole in a specific object, such as a pipe bore.

Read: Logic Gate Truth Table

Examples of Screw Micrometer Problems and Discussion

To understand more about this measuring tool, here are some examples of questions and their discussion, namely:

Calculate the results of the micrometer screw measurements in the picture below!

Answer:

The main scale is 1.5 mm. The rotary scale shows a line parallel to the main scale measuring 0.29 mm. Thus, it is known that the main scale and the rotary scale measure 1.5 mm + 0.29 mm = 1.79 mm.

Knowledge of this screw micrometer has become a basic science that most people must know. Therefore, understand the explanation above to better recognize the function of this measuring instrument.