- Hello, and welcome to this Haas Tip of the Day.
What I hold in my hand is the modern world, the result
of thousands of years of manufacturing refinement.
Okay, a bit much, maybe?
This is actually a hub for our side-mount tool changer arms,
but what it represents is incredible.
The fact that we can measure every feature on this part
with near certainty allows us to machine
perfect part after part, and those can be shipped
all over the world where we know that they will fit
into an assembly just as designed.
Part interchangeability in our modern assembly lines
are only possible because of good machinists
making and measuring, measuring, good parts.
Now in today's video, we opened up our toolbox
and we pulled out some of our most basic
hand measuring tools, (laughs) okay, okay,
some of our most basic handheld measuring tools,
and what's needed to use 'em, so stick around.
Everything for me begins with my setup.
So check this out, I've got a block loaded up.
Now if you're tightening up those tools by hand.
These are the measuring tools
that we're gonna take a look at today, and we're gonna spend
most of our time on calipers and micrometers.
If you work in a machine shop,
this is what you have to master if you wanna progress
in the trade, so we're gonna start with our trash bags.
Where else would we start a video on measuring tools, right?
So let's take a look at the fine print.
It says here that these bags are 1.1 mil
or 27,9 ums thick.
Did I sound like a machinist
when I read off (laughs) those numbers?
Nothing I said sounded like a machinist.
So can anyone tell me how thick these trash bags are
in inches or in millimeters?
There are still some industries here in the U.S.
that refer to 1/1000ths of an inch, .001, as a mil.
You might hear that term when measuring
the thickness of paint or a plating thickness,
or when measuring the thickness
of plastic sheets or plastic bags.
But as machinists, we don't use the term mil.
It just doesn't sound right.
We use the term thou, as in 1/1000ths of an inch.
Mil sounds too much like millimeter and it's just confusing,
so we need to learn the slang of the machinist
if we wanna be understood.
This is one inch, 1.0.
This is 1.1 inch,
or one inch, 100 thou.
This is 1.15 inches,
or one inch, 150 thou.
This is 1.157,
which is one inch, 157 thou,
and this is one inch,
157 thou and 5/10ths.
This is basic stuff, but that just makes it
all the more important to get right around the shop.
In the same way that the thou is the base unit
for the way we talk in the inch system,
the um is the base unit for the metric system (laughs).
Okay, it looks like um. (singer humming)
But don't call it that, okay? (record scratching)
You'll sound really, really weird, like I did just now.
This is actually a lowercase Greek mu
followed by a lowercase M, and this stands for micrometer
in the metric system, one millionth of a meter
or 1/1000ths of a millimeter.
Now to avoid confusion between this micrometer
and this micrometer, we just call
1/1000ths of a millimeter a micron.
So .001 in the imperial system is one thou.
.001 in the metric system is one micron.
That means that these trash bags are 1.1 thou thick,
about 28 micron.
That is how a machinist speaks, a thou and a 10.
Now these trash bags over here, three mil thick,
which is three thou thick, or about 76 micron.
Ooh, this might be a great spot to mention
that there are exactly 25.4 millimeters per inch,
so we can use those numbers to convert
from millimeters to inches or inches to millimeters.
Well, now that we know the language of the machinist,
thou and microns, we can move over to our yardstick.
Now on this yardstick, the graduations come,
oh, a graduation is just the line that we measure to.
On this yardstick, they come every 1/8th of an inch,
so one divided by eight
equals .125 inches or 125 thou.
Here in the States, you've gotta get really good
at converting between fractions and decimals,
so 1/8th of an inch, 1/4 inch, 1/2 inch,
3/4 inch, and so on.
Now for the metric meter stick,
the graduations come every millimeter.
There are 10 millimeters in a centimeter
and 1,000 millimeters in a meter.
Way over here on this meter stick, if we look right here,
we could call this 58.5 centimeters
or 585 millimeters, either way.
So this is our meter stick, our yardstick,
and it is not the most accurate measuring tool.
Now our tape measures are only slightly better,
but they're really useful as machinists
when rough cutting material.
Right off the bat, I might think
that this tape measure is broken.
The end is all wobbly.
Now how accurate can that be?
Not so fast (laughs), it's not broken.
The end hook on a tape measure is supposed to move.
The hook is slotted so it can slide on its rivets
forward and back by the width of the hook.
It can give accurate measurements
while either pushing or pulling, genius! (laughs)
Now I know this is basic, but it's good, right?
Every machinist needs to know this.
Accurate measurements start with knowing your tools.
Now actually, over the last few years,
I've seen more and more ads online
that actually specifically ask that operators
know how to use a tape measure.
It's the basics.
So on an inch tape measure, the graduations are now coming
every 1/16th of an inch, one divided by 16,
.0625, 62 1/2 thou.
For metric tape measures,
the graduations are still coming every millimeter.
No big change there, pretty consistent.
Here we start getting into some machinists' tools
that are accurate enough to make
some pretty decent measurements.
I'll often carry around one of these in my shirt pocket.
Now a lot of us got scolded at our first machinist jobs
for calling this a ruler.
The old guys will chime in and say
a ruler is a king or a queen.
This is a scale.
What's funny is that these typically
aren't scales anymore, either.
Back in the day, our grandfathers would hand-draw prints
using architect or engineer scales
to get the proportions correct
when not drawing parts life-sized.
When a drawing is the same size as a real part,
we call that scale 1:1.
If the drawing is half the size of a real part,
the scale would be 1:2.
Now here are my grandfather's old scales
with different ratios.
The graduations on them vary
based on the scale we wanna draw the part at.
The machinists' rulers or scales that I use today
typically have a precision edge on them
and they're just called steel rules.
These typically come with graduations
of 1/32nd and 1/64ths of an inch,
while metric steel rules will go down
to millimeter and one-half millimeter graduations.
So our rulers that we've looked at
have graduations all over the place,
1/8th inch, 16th, 32nd, and 64th graduations.
And this can get really confusing.
We've just gotten used to it here in the States
and we've gotten really good at converting fractions
into decimal inch values, which brings me
to one of my favorite machinist quotes.
Instead of our engineers and machinists
thinking in eighths, 16ths, and 32nds of an inch,
it is desirable that they should think and speak
in tenths, hundredths, and thousandths.
This was written by Sir Joseph Whitworth way back in 1857.
In fact, he coined the term thou,
1000ths of an inch, way back in 1844.
Thank you, sir.
So the steel rule that I tend to carry
most often in my pocket is actually a decimal inch version.
It'll have the .1, .2, .3 inches
on the one side, which match up well
with our decimal inch digital micrometers
that we were looking at, and our Haas control,
which doesn't list things in 64ths.
It lists things in decimal inches,
so no more scant or heavy 64ths.
This is by far my favorite steel rule.
Now if you wanna look like a real pro when using
a steel rule, be sure to set it on its edge when measuring.
You'll get much more accurate and repeatable measurements.
By placing the rule on its edge, we avoid parallax,
where the measurement appears to change on us
based on the direction we view the graduations from.
Each of these measuring instruments
has a different accuracy of precision
that a trained person can be expected, trusted to hold
with one of these instruments.
Often, but not always, the accuracy
or precision of an instrument is the same
as the smallest graduation on that tool,
so our yardstick had 1/8th inch graduations,
and these calipers here, ah, which have to be
the most versatile tool on this table,
have a resolution down to 5/10ths,
while these dial calipers here
have a smallest graduation resolution of one thou.
Now in reality, I don't use calipers for numbers that small.
Once I go down below a couple of thou or a thou,
I'll start using micrometers,
so that's just typically what we do.
Why push the limits?
To be used accurately, these need to be zeroed out
with each use, held square to the part,
and used with just the right amount of force, not too much.
We'll wipe the reference surface with a lint-free cloth
and we might wipe that same surface
with a drop of micrometer oil.
We'll open and close the calipers to make sure
nothing is dragging or catching, and if the calipers drag
while opening or don't fully close, the calipers
might have been damaged and they'll need repair.
We'll wipe clean the measuring faces and close 'em snugly.
We can hold the calipers up to a light
to make sure there is no gap between the jaws.
If there is, clean 'em again or get 'em repaired.
With the jaws closed, we'll origin or zero out the calipers.
I'll open and close 'em a few times at this point
to make sure I get zero repeatably.
We can zero out dial calipers by rotating the bezel
and snugging the set screw.
These calipers are like the Swiss Army knife
of machinist tools.
They can be used to measure inside features,
outside features, depths, or a step or a shoulder.
I have five things for you to watch out for
when using calipers as you gain experience.
One, don't push too hard, and keep the part
as deep in the jaws as possible.
It's a good idea to hand a new machinist a gauge block
or a standard to practice with when they're getting a feel
for how hard to press.
If you don't get the number
on the standard gauge block or pin,
then you are pushing too hard or too lightly.
Number two, make sure that your calipers
are square to the part that's being measured.
If they're tilted, you could end up with errors.
Number three, watch out for the radiuses left by tools.
These can throw off your numbers.
This part has a 10 thou inside corner radius,
which can affect my values.
In this case, I just rotate the calipers
to allow the notch on the depth-measuring face
to avoid that inside radius.
Number four, these calipers are great for measuring IDs,
inside diameters, of holes, but not small holes.
When a hole is smaller than four millimeters' diameter,
157 thou, these inside diameter jaws
aren't gonna fit cleanly, and your numbers are gonna be off.
You'll usually show the hole
being smaller than it actually is.
This happens just because of the physical design
of all calipers, even the good ones,
so for really tiny holes, you're probably better off
going with a small bore gauge or gauge pins of some kind.
And number five, if you're using a dial caliper,
make sure you're looking at the needle from straight on.
If you're looking at it from the side,
we'll get parallax error, like we saw earlier
with the steel rule.
Once you're getting some good measured numbers
with your calipers, we can try some advanced caliper tricks,
like coming up with the center to center distance
between two holes.
By zeroing out your calipers on the ID of a hole,
you can then easily check the center-to-center distance
between holes of that same diameter.
This makes reverse engineering some parts go really quickly.
This little trick is why I prefer
digital calipers over dial, that and the fact
that we can change them from inch to metric quickly.
And they look great in a holster.
(dramatic cowboy music)
For more precise measurements,
we're gonna set our calipers down
and move up in the world to micrometers,
not to be confused with micrometers (laughs), okay?
Now the biggest difference, one of the differences,
between calipers and micrometers is that calipers can work
across an entire range.
These are eight-inch calipers.
They work from zero to eight inches.
Now micro (laughs), micrometers, have a limited range,
usually one inch or 25 millimeters.
Now this set of micrometers,
which covers zero to six inches,
requires six different micrometers, zero to one, one to two,
two to three, five to six, et cetera.
The reason I mention this
is that they are zeroed differently, and micrometers,
the zero needs to be checked with every use, right?
And so this is something that's important.
Look, the spindle on these one inch or 25 millimeter mics
can close all the way against the mic anvil,
all the way to zero, and as I do that,
it's a good time to check to make sure that there's no drag,
kinda like when we were opening and closing the calipers.
As I close up these micrometers,
if we feel a drag of any type, they may have been damaged
and they might need repair, or maybe the spindle clamp
is tightened just slightly and needs to be released
or at least cleaned up.
You can use some micrometer oil and clean those spindles.
To clean and check zero on these,
we'll slowly tighten the mics,
clamping against a piece of lint-free paper.
Once lightly clamped, we can drag out the paper,
which in turn cleans the measuring faces,
and we can do this a few times.
Now I've often used whatever random paper
that's laying around to clean my mics,
but this is a bit dangerous.
If the lint from regular paper gets stuck on the faces,
it'll throw off all of our measurements,
so lint-free paper is the way to go.
Okay, all clean, no lint.
Time to tighten up these micrometers and check out our zero.
Now here's where we run across
what might be the number one issue, cause of mistakes,
when using micrometers.
I'm talking about gorilla grip.
If we over-tighten these mics, (gorilla grumbling)
our measurements can end up being off by quite a bit.
In fact, if you are buying a set of micrometers,
it's worth it to spend a little extra
and get a force-limiting device,
like a ratchet stop or a slip clutch of some kind,
which help give us a consistent clamp,
whether measuring a part or setting our zero,
and it helps us prevent gorilla grip.
Now for our digital mics, we'll just close them
and origin them out, setting them back to zero.
Now if we're using larger digital mics, these big ones,
we can clean the measuring surfaces and origin them
while clamped on a standard or on a gauge block.
Now for checking zero on our analog mics,
we'll do the same thing.
They're all closed, ready to go, and they should read zero.
If they don't read zero, then we have to adjust them,
and to do that, we're gonna take a little wrench,
the little spanner wrench that came with the micrometers,
and we're going to lock it onto the sleeve
and rotate it slightly until the lines line up, zero zero.
Now this doesn't have to be done often,
so if you're new to machining and you think
your mics aren't reading correctly,
grab a buddy and have him take a look at the mics
before you make any adjustments.
Again, that sleeve might be hard to turn
if it hasn't been adjusted in a long time,
so you might have to clamp it in a mic vise.
You might actually have to tap on the spanner wrench
just a tiny little bit with a hammer.
With our mics all zeroed out, we can measure a part.
Now I'm gonna grab these digital mics and this part,
and I'll set it on here.
We're gonna jiggle things
to make sure everything's nice and square.
We're gonna rotate our ratchet stop a few revolutions,
click, click, click, and then there's our number,
595 thou and 2/10ths.
Now to get that same measurement with an analog mic,
we're gonna have to read between the lines
and do some addition.
For inch micrometers, the main graduations
etched on the sleeve are 100 thou apart,
.1 inch, .2, .3, four, five.
That's .5 inches.
We haven't quite made it to six.
We haven't graduated to .6.
The smaller graduations on the sleeve
are 25/1000ths of an inch apart, 25, 50, 75,
and we aren't quite to our next line yet,
so we'll call this .575 so far.
But wait, there's more.
Now we move over to our thousandths graduations,
which are etched on the micrometer thimble.
Our highest full line number is 20,
so we just add this in,
.595, 595 thou.
Actually, we're just a little bit over that.
We're kind of in between 595 and 596,
so for higher precision out to 1/10th of a thou,
we'll look over to these numbers, zero to nine,
etched around that circumference of the micrometer sleeve.
These markings are part of what we call a vernier scale,
and there's a secret code to them.
They help us read between the thou lines, the graduations,
on our thimble for higher accuracy, higher precision.
For this vernier micrometer scale, all we do
is look over all 10 numbers, zero through nine,
and decide which one best lines up
with the thou graduations on the thimble.
Now it doesn't have to line up
with any particular thou line.
Any one of 'em will work.
It just has to line up well.
Our eyes can play tricks on us,
so we have to be careful to avoid parallax.
Yeah, just like that steel rule.
We need to look straight down at those numbers.
So finishing up our math lesson here, we have .5
plus 25, 50, 75, plus 20, plus 2/10ths
gives us .5952, 595 thou and 2/10ths.
Metric micrometers are very similar, with graduations
of one millimeter and half a millimeter on the sleeve,
graduations on the thimble every .01 millimeters, 10 micron,
and a vernier scale on the sleeve,
which lines up to an accuracy of one micron.
We'll see these vernier 10th scales
on lots of different kinds of micrometers,
so it's something we really need to master.
So that was some pretty solid instruction
on calipers and micrometers, our common tools.
I'd like to quickly gloss over bore gauges,
gauge pins, and blocks before we let you loose here
just so you know what people are talking about
when you see 'em.
Bore gauges are used
to accurately measure hole inside diameters.
Now they are similar to micrometers
in that they are only good for a certain range of bore.
This set comes with adjustable anvils, rods,
that can be swapped out or stacked so the gauge can be used
with different diameter holes.
Now we'll typically zero out our bore gauges
using a precision ring gauge, and we'll check this often.
And like all dial gauges,
we need to look straight at the needle to avoid parallax,
and digital indicators can also be attached.
Now for small holes, these plug gauges,
also called gauge pins or go/no go pins, are just terrific.
Once the correct pins are chosen,
if the go pin fits and the no go pin does not,
we can quickly gauge whether a hole is in spec.
Now you can order these pins in varying tolerances
based on how tight the print tolerance is
for your particular feature.
Now similar to our plug gauge is our thread gauge,
or our thread plug gauge.
Now we'll order these up in a go/no go
based on the callout from our blueprint.
This is a 5/16th-18 thread
with a fit tolerance of 2B.
Now for most threads, we'll check the hole size,
the thread minor diameter, with a go/no go pin,
and then check the thread pitch itself
with a go/no go thread gauge.
This is a good thread. (cash register dings)
Some of you have noticed
that I'm measuring this particular part after coating.
Now you'll need to watch out for coatings.
This part has a black oxide finish on it,
which is a conversion coating and leaves virtually
no buildup, so we don't have to mask anything on it.
If this were an aluminum part getting anodized,
you'd really have to plan out the entire part,
deciding if you were gonna mask certain holes or not
or if you needed to machine the part undersize
to account for the coating that's gonna build up later.
Most anodized parts might have a buildup
of a half a thou to maybe 4/1000ths of an inch,
depending on the type of anodize.
Well, we really dove deep into a couple of the common tools
that we use every day as machinists,
but we glossed over some of these other topics.
But we're gonna be making videos on those
soon in the future, so be sure to subscribe
to the Haas Automation YouTube channel
or like us on Facebook.
Well, that's it for this Haas Tip of the Day.
Thanks for watching. (cheerful music)