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Hi, this video will show you how to use the micrometer to gets measures of length down to 1/100 of a millimeter (mm).
It's a wonderful instrument. Most rulers only go down to mm, and most vernier calipers goes down to 1/10
of a mm. This one goes down to 1/100. Now of course, bear in mind ...
1/100 mm is still 10 micrometers, so the micrometer does not actually give you readings in micrometers.
It is a bit of a misnomer. Please bear that in mind
It is a wonderful instrument, but there is usually a fairly big limitation to these micrometers, it's its own size.
because what we measure has to fit into this part here. If we have that is bigger than that and it won't fit
then you can't do it with this micrometer. We will have to measure something smaller
Just before we get started, we will show you a quick rundown of some of the vocab that you may or may not need in order to use it
so we've got the anvil, spindle, frame, sleeve
the thimble and the friction clutch. So I will take it away now because it is not super important. You can pause and review.
So the thing that we're measuring is the distance between this anvil and the spindle
this gap here, that's the distance we are tracking. As we turn the thimble around, the spindle will retract and we'll get the length
With the thimble here, let's line up the 0 with this horizontal line
and we turn it one full revolution
you notice it went from 5 mm to 6 mm, so each turn on this micrometer gets you 1 mm of travel
and that one mm is divided into 100 equal pieces all the way around, so that is how we can get
down to 1/100 mm with the precision
so the last thing is in order to use it, we open this thing up
further than you need to put the part inside
Now, this part is key. As you close in on it, you want to switch from using
this part to this clutch back here
and you notice that once it closes in on the part
the clutch starts to slip
and the numbers aren't moving anymore
this is important because it prevents us from over tightening
my micrometer which will hurt the threads in here, which will hurt the instrument and you can't use it
Let's read, so the first thing we read is the mm along the sleeve here. We've got the 0, 5, 10, 15...
16, 17, 18, 19 is just kind of showing right there
so it is about 19 mm
To get the last two digits, or the fraction of a mm, we run along this horizontal line and see where it intersects,
so in this case it looks like 0.76
at this point you would want to ask yourself: is it more likely that it is 19.76 or 18.76?
given that the 19th mark is just showing, it is probably 18.76
and that is how you will have to decide almost every time
so once we finish reading the number, we should definitely double-check the zero reading
closing...
using the clutch once again near the end
and this horizontal line as it comes across. You actually notice that it is less than 0
so it is a negative zero reading of -0.01...-0.02... -0.03 mm
so when we subtract the zero reading to get our true reading, we get a bigger number.
In our case, 18.76
minus -0.03
gets you 18.79 mm
and that's how we got
the diameter of this cylinder
down to 100th of a millimeter using the micrometer
Thanks