- 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.