hey guys Chris here today I want to show
you the right way to use calipers it's
super important to be able to take
accurate and repeatable measurements
wherever you are so that you can make
the best and most well informed
decisions on your designs the majority
of the time I use calipers is to measure
existing parts that I need to design
around sometimes it's to measure a part
that I ordered to make sure it's in
tolerance but it's usually when I need
to go from a physical item indicat okay
let's go through the basics first
you have the LCD screen here that shows
you the measurements out to 4 decimal
places but that does not mean it's
accurate to 110 thousandths of an inch
the resolution of these calipers is 5/10
but the accuracy is plus or minus 1000
that means that the smallest increment
the LCD will show you is 5/10 but you
should never trust it to be more
accurate than plus or minus 1 tau when
you're looking at different calipers to
by always check the accuracy and if
they're the cheapos that don't even list
it just stay away MIDI Toyo's are
accurate and durable so you can't go
wrong with them they're by far the ones
I see most in engineers hands the zero
button makes wherever the calipers are
at the moment zero then smaller
measurements are negative and bigger are
positive which is super useful when
you're trying to compare two parts or
make a relative measurement there are a
few specific times where that comes in
really handy and I'll talk about those
later but just always keep this button
in mind when you can't figure out how to
measure something it will definitely
come in handy the origin button is used
to recalibrate the calipers should read
0 them every time you pick them up
always clean the jaws first fingers work
pretty well but a cloth is better and
then close them and see what they're
reading if it isn't zero hold down the
origin button until it's reading zero
and then if you can it's not a bad idea
to check them on a part of known size
like a gauge pin to make sure they're
good the inches millimeter button
obviously switches units between inches
and millimeters the thumbwheel here
gives you some fine control over the
jaws some people roll their thumb on the
wheel like this until it slips so they
can apply the same squeeze every time
you just have to be sure to push up like
this and not down into the wheel
otherwise it won't really slip you want
to do a nice gentle roll that way you'll
get a relatively consistent if you
to it and the locking knob on top let's
say you lock the jaws in place you can
use this if you can't read the screen
while you take the measurement or if I'm
honest I'll use it sometimes so I don't
forget a measurement crossing that room
now that you know what the buttons do
how do you actually use calipers first
definitely don't be too rough with them
they are variable but you don't want to
bend them or mess up the jaws especially
the little tips when taking a
measurement gently squeeze the jaws
together by pushing here or rolling the
wheel like I said before the key is to
be consistent with how hard you squeeze
if you can't get a measurement the same
measurement two or three times in a row
then you're doing something wrong if you
squeeze too hard you can bend the jaws
damage the part or mess up a sliding
elements inside the calipers some people
will push the jaws together here when
possible to make sure there's no bending
going on to see how hard to squeeze you
can use a gauge pin since I know this
gauge pin is half an inch in diameter
plus nothing minus two tenths of an inch
I know it should read 0.5 zero zero zero
on these calipers so there we're good
but if I squeeze harder I can make the
value change especially the further out
on the jaws I do it that is too hard you
want to be able to repeatedly measure
half an inch second you need to know all
the places on the calipers that you can
use to measure if the screen shows one
inch then it's one inch between these
jaws it's one inch around these jaws
it's one inch between the step here and
the end of calipers and it's one inch
between the end here and the scent of
the calipers which reference you use is
up to you depending on what you think
will get you the most accurate
measurement but in general here's where
you'll measure outer diameters inner
diameters step Heights and hole dips
personally I use the jaws most the time
these second than the depth measurement
and I hardly ever use the step but
depending on what you measure the most
that could be totally different the
third thing to know when using calipers
is it just because the screen shows a
measurement does not mean it's right
it's the same as any other tool garbage
in equals garbage out if you aren't
careful to make sure your calipers are
clean and oriented correctly you might
as well not even bother taking the
measurement for example
when measuring a shaft Bandler used this
part of the jaws not the tips the flat
section at least gives you a little
reference so you can tell you are off at
some weird angle measure at multiple
points around the shaft also different
points along the shaft and stay away
from little internal radiuses like this
though I'll mess you up every time
another thing to keep in mind when
measuring an OD or a width is that the
more you can increase the area of
contact between the calipers and the
part the better if I measure
perpendicular to the axis of the shaft
like this the contact patch is aligned
the width of the caliper jaws but if I
can rotate the calipers like this the
line contact doubles in link and you're
less likely to miss a high spot or be at
an angle measuring inner diameters is
trickier but this is how I do it if you
just throw the calipers in there take a
measurement you're probably gonna get me
wrong what I'll do is I'll swing the
jaws back and forth like this around the
opposite sides of the diameter keeping
the jaws dragging across the ID you'll
be able to feel the jaws open and close
slightly as you swing back and forth
across the true opposite points you
might also be able to see the value on
the calipers go up and down slightly
once I'm satisfied
that I have the max value in that
direction I'll rock the calipers in this
direction to make sure I'm not off at
some weird angle to the axis of the hole
just do that a couple of times in a
couple of different spots on a diameter
until you're satisfied and you have a
good measurement whole depths and step
Heights are pretty obvious just do
whatever you can do to make sure your
calipers are perpendicular to your
surface in all directions make sure
you're good this direction and that
direction measuring the full thread
depth of a hole is pretty easy and super
useful so this is how you do it first
you measure the overall height of the
bolt you zero out your calipers and you
thread the bolt into the hole all the
way until it stops then you measure the
height of the bolt that's still sticking
out and that is the usable depth of
thread in your part one thing you have
to watch out for is to stay away from
their grade markings on the head of the
bolt that'll mess you up
the useful trick with your digital
calipers is to be able to measure the
center to Center distance between two
holes the holes have to be the same
diameter for this to work first you
measure the ID of one of the holes and
easier your calipers at that diameter
now you measure outside to outside on
the two holes and that is your center to
Center distance now since this involves
like two measurements and zeroing and
things I wouldn't necessarily use this
for like a plus or minus one dimension
but you know definitely for clearance
holes on a prototype part you're making
or something like that if you need to
measure the thickness of foam or an
o-ring something that squishes what you
can do is grab your part just enough to
to suspend to hang it there and then
very slowly open up your jaws till it
drops and that is the thickness of your
part otherwise you can never really tell
if you're kind of squishing the material
it's hard to get a good feel for it so
just try to get the part where it's not
curved and hanging up on two different
points on the calipers if this part was
really curved like this measuring it
like that would not be a good idea
because you're not going to get the
right dimension so measure it in a way
that it'll be free to fall help from the
calipers then you move them apart a
topic that isn't strictly related to
CalPERS but is related to taking
measurements is the use of the terms
foul and mil when I first heard someone
say that such a such dimension was 3ml
to bei I was super confused but they
need millimeters do they need millionths
of an inch nope they meant thousands of
an inch why would there be two shorthand
ways of saying a thousandth of an inch
well according to Wikipedia the term mil
used to be the standard and is from the
latin word mealy but when the metric
system started to become more popular
then it got confused millimetre and mil
was too easy to get confused so we
started saying that for some reason
mills are still the standard for some
products like sheets of plastic so be
ready for that so now you know how to
use calipers if you use them very often
this law becomes second nature but just
remember
to set zero when you pick them up make
sure your part and calipers are clean
make sure your calipers are oriented
correctly and should be just fine if you
have any other caliper tips or tricks
please leave them in the comments below
so we can all learn a bottom thanks see
you next time
you