– Here’s just one of the specialist tools you’ll learn about in the engine building fundamentals course. When it comes to building

engines, the micrometer is one of the most common

pieces of precision measuring equipment that

we’re going to be using. Now I know that a lot of

novice engine builders and mechanics really struggle

with how to correctly use and read a micrometer,

so in this module we’re going to see exactly

how to go about doing it. Now while there are a few

varieties of micrometer available, we’re going to be focusing here on an imperial scaled vernier micrometer. Now of course if you’re

using a digital micrometer, using the micrometer is

relatively straightforward because the reading will

be displayed digitally right in front of you. However as we’ve already found

out, we are going to need a range of different

micrometers, in order to measure the different sizes we’re

likely to come across in the engine. And since the digital

micrometer is more expensive than a conventional mic,

this is going to add greatly to the cost of your tool set. Now here in front of me

I have two micrometers, and these are a relatively cheap brand coming out of China, as we

see with a lot of the common equipment we’re going

to be using these days in engine building. And in front of me here I

have a zero to one inch mic, and then I have a one to two inch mic. This particular set goes all

the way up to six inches, and we’re simply going

to select the micrometer that’s suitable for

whatever we’re actually trying to measure. Now with the micrometers

there are two different types. There is a vernier micrometer

which is what we’re going to be looking at today;

this is able to measure down to four decimal places or 1/10,000 of an inch. Or we can use a conventional

or standard micrometer. This eliminates the

vernier scale and is able to measure down to 1/1,000 of an inch. For today’s lesson we will be

looking at the vernier scale, however what we’re going

to learn will be applicable to a standard micrometer as well. Before we get started

using the micrometer, we’re just going to have

a look at the different components that make up the micrometer. This is our one to two inch micrometer, and first of all we’re

going to have a look on the little plaque here; we can see that it’s labelled 1-2″, and

we can also see that the precision of this

micrometer is also listed; you can see it’s listed

at 0.0001 of an inch, or 1/10,000 of an inch. I’m just going to flip it around so we can actually see the scale, and we’ll just talk about the different

components of the micrometer. First of all, we have the

frame which actually holds both ends of the micrometer. The two measuring surfaces

are between here and here, this particular component

is known as the anvil, and this part which moves

as we turn the screw thread is known as the spindle. Here we have our measuring

scale, which we’ll be looking at in more detail shortly. This particular component

where our scale is written, is known as the barrel or

sleeve of the micrometer. Next we have the turning

component which is known as the thimble. And finally, at the end,

we have our ratchet stop which is what we’re going to be using for actually tightening

the micrometer down on the component we’re measuring. We also have a positive

stop which we can use to lock the micrometer

once we have measured the component of interest. Now that we’ve seen the

different components of the micrometer, we’re

going to look at how we can actually use a micrometer

to make a measurement. Before we make any

measurements, it’s important to make sure that the

measurement faces of the anvil and the spindle are both clean

and free of dirt and debris, as these can have a dramatic

effect on the accuracy of our reading. Now what we’re going to do

is close down the micrometer, and just make sure that it is

able to accurately read zero; so what we’re looking at

here, is that this zero line here lines up correctly and

accurately with the zero mark on the barrel of the micrometer. Now we’re just going

to talk about what each of these increments mean. Now the increments on the

thimble of the micrometer, represent 1/1000 of an inch, so every time we move past

one of these increments, we’re increasing by 1/1000 of an inch, so at this point we’re reading 5/1000 of an inch. Now every time we go

through one full revolution, we come back to zero. This means that the

micrometer has incremented by 25/1000 of an inch. And we can also see that as we do this, a new mark is now visible on

the barrel of the micrometer. So I’ll just open it up a

little bit further so we can see these marks a little bit more clearly. So each of the marks along the barrel represents 25/1000 of an inch, and we can see that

when we get out to four of these marks, we have a value of one, and this represents 1/10 of an inch, or 0.1 of an inch. Now on the top of the scale

here, we have our vernier marks, and these are going to be

used to define our fourth decimal point, or our

1/10,000 of an inch precision, and we’ll see how that works shortly. Now that we know a little

bit more about what these numbers mean, let’s

actually measure a component and see how this all works. Okay, so now we’re going

to actually measure the width of this piece

of aluminium, and you can see how I’m holding the

micrometer; they’re made to be used in your right

hand, and while this is a little bit tricky because

it is a small micrometer, you can see I’ve got my

little finger just looped through the frame, and I’m using my thumb and forefinger on the spindle. We can make coarse adjustments

by using the thimble, but when we get to a

point we’re actually ready to make a measurement, it’s important to use the ratchet stop,

and this prevents us over tightening the micrometer. So once we’ve got the

micrometer tightened, and it’s stopped moving,

we can then lock it; and we can remove the

component that we’re measuring. Let’s now have a look

at how we can calculate or measure the component that we’ve just put in our micrometer. When you’re learning to read a micrometer, it’s valuable to write down

each of the measurements as you read them, and

then add them together; this makes it very clear

exactly what the measurements are, and we’re going to do that. But let’s have a look at

what the numbers mean. The first thing we want

to look at it is how many numbers are visible on the barrel or sleeve of our micrometer. Here you can see that

we have the number three being exposed, and what

this means is that we have a measurement of 0.3 inches. Beyond that, though, we

can also see we have three more increments exposed. Remember each of those

increments represents 25/1000 of an inch, so three of those represents 0.075 inches. So we know that at this

point we have 0.375 inches. We can also see though, that,

we’ve come up just beyond the number five; remember the thimble here represents 1/1000 of an inch, and we can see that we’ve gone

a little bit past the five. So we’re somewhere

beyond 5/1000 of an inch, and this is where the

vernier scale comes in. What we want to do is have

a look at our vernier scale, and see which line comes

closest to lining up. We can see in this point, the six lines up correctly

with our vernier scale, which is our fourth decimal point, or 0.0006 of an inch. Let’s write all those down and add them up so we can so we can see

what our final value is. When it comes to writing

down the measurements from our micrometer, it’s

always best to look at them each individually, and then add them up. We’re going to start

with our 1/10 of an inch measurement, which we

can see here, remember we had our value of three, our measurement of three visible and that

represents 0.3 of an inch. I’m just going to add out

to our four decimal places just so everything lines up when I’ve got the rest of our measurements listed. Next, we have our little increments, and you’ll remember each

of those smaller increments represents 25/1000 of an inch. We can see that three

of these are visible, and that represents 0.075 of an inch, so let’s write that down. Now we can see that we’ve also gone past on our thimble here, we’ve

gone past our five-thou mark, so we’re going to also write that down. And you’ll remember that

when we were looking at our vernier scale,

on the top of the mic, we had 6/10,000 of an inch, so we’ll write down our

last value there as well. Okay, so this represents the measurement from our micrometer, and

what we need to do now is add up the different values. So, we have 6/1000 of an inch; we have two fives here

which add up to equal 10 so we’re just going to carry the one; we have an eight, and a three. So our final measurement

is 0.3806 of an inch. Like any piece of equipment,

using a micrometer does take some practise

to become competent with, but now you should understand the process to go through, and how to correctly read the numbers on the micrometer. That was just one of the modules from the engine building fundamentals course, which is the perfect starting place if you want to learn how to assemble high performance engines. This course will teach you about engine anatomy, essential engine machining processes, how to select and measure critical clearances in your engine, how to assemble the engine long block, and how to break in your fresh engine. For more information and to purchase the course, click the link now.

## 11 Comments

Hey thanks for the refresher!!!

Inches? Is Australia not metric…

lol andre that thumbnail looks like your pointing with a joint… still love ya man

Want to learn more about performance engine building? Come along to the next free live lesson – www.hpacademy.com/free-engine-building-lesson/

Thanks great way to remember. You are on point with what your talking about than my instructors. They'll just have you give it a go or a demonstration with the ticks on the micrometer and you'll figure it out on your own. It's like if you see a pattern you'll figure it out. Btw note. you spells micrometer wrong for the title. lol

I was 16 when i learn how to read this tool and others in my 4 year mechanic apprenticeship.

Was a bit confusing at first time đź™‚

I always have to write it down to get the reading… If I don't I get lost lol. Once I have a baseline though if measuring a crank for example I then only write down the last didget in most cases.

Love your channel brother!

great video guys, very clear instruction

Excellent video! Thank you. I don't use micrometers very often and always forget how to read them.

i can read micrometers better then calipers