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a caliper or set of calipers is a tool
used to measure the distance between
opposite sides of an object usually with
much more Precision than something like
a ruler you can find them in many fields
including woodworking metal working
medicine mechanical engineering and many
other Sciences so while they're not
related to electronics exactly I find
myself reaching for my trusty calipers
all the time to do things like measure
the distance between leads on an
electronic component when it's not
listed or I can't find the data sheet
the first set of calipers discovered
date back to the 6th century bcee and
they were tools used Often by the
ancient Greeks and Romans to make
precise measurements Bron sliding
calipers from the Han Dynasty were also
unearth dating back to the year
9ce most modern slide calipers work on
the same basic principle there is a
fixed main scale attached to one or more
sets of Jaws and a slider that moves
linearly across the main scale the
slider has the opposing set of Jaws
which move to measure the object in
question you can read the distance
measured by looking at how far the
slider has moved on the main scale many
calipers have a thumb wheel that gives
you more precise control over how the
slider moves and most calipers include a
lock screw you can tighten to prevent
the slider from moving to hold the last
measurement taken this can be helpful if
you need to move the calipers away from
the object to read the scale or if you
want to compare the dimensions of two
different objects without writing down
the measurements you'll generally find
slide calipers in one of three types
verer dial and digital verer calipers
use two sets of rulers to get very
precise readings because they have so
few moving Parts they are often more
reliable than the other two types
however learning to read the verer scale
can be tricky and require some math
every time you want to take a reading
dial calipers are easier than verer to
read but use a rack and pinion to
display the fine measurement on the dial
this added mechanical complexity means
more points of failure which means that
it's easier to break and harder to fix
dial calipers digital calipers use a
series of conductive pads in the main
scale and another set of pads in the
slide to measure capacitance as the
slide moves the distance the slide moves
is shown on the L CD this makes digital
calipers very easy to use and read but
the battery on mine seems to die
whenever I need it the most before you
begin taking measurements it's important
to zero your calipers otherwise your
readings might be off you can't zero a
verer caliper because the scales are set
in place if you do notice that the zeros
don't line up when you close the Jaws
you'll have to read the error on the
calipers and add or subtract it from
your measurement or buy new calipers to
zero dial calipers close the Jaws if you
see that the needle on the dial does not
line up with zero loosen the lock screw
on the dial and twist the dial face
until the zero tick mark lines up
perfectly with the needle tighten the
lock screw and you're good to
go for digital calipers once again make
sure the Jaws are completely closed if
you don't see Zero on the display press
the zero button modern slide calipers
generally have two sets of Jaws and a
depth Rod to measure an object like this
piece of PVC pipe close the outside Jaws
around the points you want to measure it
can help to wiggle the object or move it
back and forth while gently applying
pressure to the slider to get the
minimum measurement of the longest
distance on the part you want to
measure to get an internal measurement
use the internal Jaws similarly you'll
want to wiggle the object so the Jaws
fit nicely in the opening to get the
maximum reading
possible finally you can use the depth
Rod to measure the depth of an object or
hole rest the main scale part of the
caliper on the object and move the
slider until the depth Rod reaches the
bottom of the hole or Surface you will
want to make sure your bottom surface is
flat and that everything is at right
angles to get the most accurate reading
when you have the measurement you want
you can tighten the lock screw so you
can look more closely at the
scales now that we have our calipers
locked to the measurement we want let's
take a look at how to read them we'll
start with digital calipers since
they're the easiest assuming the
calipers were on and zeroed when you
started you can just read the numbers
right off the display and many digital
calipers include a button to change
units between inches and
millimeters dial calipers require a bit
more effort to read and they usually
only come in either Imperial or metric
to read them find the largest
measurement on the main scale visible to
the left left of the slider in this case
it's 1.6 in then read the dial which is
68 in this example since the dial says
it's an increment of 1 1000 of an inch
we know it's 068 in add the coarse and
fine measurements together and you get
1. 668
in verer calipers can be made with both
Imperial and Metric scales but they
require the most effort of the three to
read the fixed part is known as the main
scale and the slider is printed with the
verer scale find the largest measurement
on the main scale just left of the zero
on the verer scale write that number
down which is 42 mm in this case then
carefully look at the lines on the verer
scale and find where one perfectly lines
up with a line on the main scale write
down the reading of that line from the
verer scale which is
3.6 if the verer scale on your calipers
is marked with an increment then you can
easily figure out what the verer
measurement is and add it to the main
scale measurement however some verer
scales aren't marked with an increment
so you'll have to do some math verer
scales are designed to show where the
measurement lies in between two marks on
the main scale it's like you've zoomed
in to view even more increments in
between marks on the main scale so to
find the value multiply your reading by
the smallest division on the main scale
1 mm in this case divided by the number
of large divisions on the verer scale
which there are 10 of for my calipers
for this example we would get 36 mm on
the verer scale add that to the main
scale reading and you'd get
confidence I have a set of verer
calipers for when I need the reliability
but more often than not I reach for my
digital set and if you find that the
coin cell battery in them keeps running
out too quickly you can mod them for a
little extra
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