hey everybody adam savage here at my cave with another dive into metrology that is
the study of the measuring of things and i've covered some metrology a bunch of late
i've talked about calipers i talked about my favorite four-inch calibers by mitutoyo
actually also by mitutoyo i recently did the build of my uh a micrometer case using these kind
of barrel micrometers um i use these calipers all the time but i've recently received a new
measuring device and it is um it illuminates another aspect of measurement which is
i find fascinating okay if you haven't watched my video about making the case for my mitutoyo my
micrometers um please do it's a lovely video in the box that i uh modified for the collection that
allows me to measure plus or minus about a less than a half a thousandth from zero to 12 inches
if you haven't watched that go watch it but even if you've watched it
well i just want to cover one thing these types of barrel micrometers have up here a ratcheting head
you hear that okay and so what that head does is
the ratchet allows you to apply a constant amount of force if you if you grab a piece of plastic
for instance in this and you torque down on this you'll be able to actually compress that plastic
so how do you know and the same could be true for a soft metal the same could be true for a
dimensional thing you're making that you don't realize compresses how do you know that you're
getting the same measurement every single time the ratchet in here helps do that because
you're not applying more force to the barrel you're applying the same amount of force to
get that ratchet every single time and as long as that ratchet happens you know you're getting a a
comparable measurement each time i bring this up to talk about well i mentioned if you're
measuring a piece of plastic you could compress it what happens when you have to measure
a piece of leather or a piece of felt in a factory that makes something out of leather or
felt there comes a requirement for certain amounts of thickness um this is absolutely true with the
aprons that we manufacture we use the same type of leather for the pockets um and for the the the
hammer rings but the pockets leather has to be thinner than the hammer rings because
because of their different requirements in terms of strength so if i measured this piece
of leather with this micrometer what you'd see is there's this variance of about six thousands
in terms of how much pressure i can put on this i mean i can put it on and let it settle back
but is that going to be enough is that going to be the right measurement and when it comes to
something that's even softer like this felt well how do i know what my measurement is
so how do i measure the thickness of something like felt i can't i can't measure its absolute
thickness because its absolute thickness is an average across a whole bunch of measurements
plus under an electron microscope the line between the material and the lack of material is also
somewhat of a gray area the material gets thinner out towards the edges it's in a case like this
it's not about the absolute value it's about an absolutely agreed upon methodology
to obtain the value so in industry the methodology for measuring i don't want to say the methodology
in the industry of manufacturing one of the methodologies for consistently measuring the
thickness of goods that are somewhat compressible is to use a specific type of micrometer
that has a certain amount of pressure to it that is the same for everything it measures and
this ladies and gentlemen is that micrometer the biggest dial based instrument i now possess in my
shop sits here before you made by the uh ej katy and company uh out of chicago this is an automated
automatic micrometer to the thousandth of an inch and it is a beautiful device i recently came
across it on craigslist um and purchased it and i think i may do a restoration on this and and make
it even more beautiful than it currently is which is a fairly tall order because it's magnificent
but let me explain to you how this works based on what i've talked about in this video so far
let's get you a little closer to the action here this micrometer is composed of several parts first
and foremost is its dial there is its dial and it is beautiful dial look at i mean this is gigantic
what is this yeah it is a six-inch diameter dial man that is bigger than all my other dials
by like four and a half inches um but its operation is even more beautiful you open this
you push on this lever ah there you sell that okay so what happens here is that this little
piston comes up and what this is called down here is the anvil these are two flat surfaces that meet
you lift this and it falls back down again you lift this and it falls back down again
the thing is it falls back down with a very specific amount of pressure in fact between five
and nine or is it five and seven it's between five and seven pounds per square inch of pressure
that's how much pressure this puts and these are manufactured through an incredible level
of consistency ej kd still exists they still sell these and this is the kind of thing as a factory
manager you would have at your desk you get a new shipment of felt you would put it in the
anvil and you would take the measurement see this i'm not touching this i'm not squeezing
it i'm not wondering where it ends up i am literally letting the anvil fall down on it
and i can tell you that according to this at five to seven psi this is 200 000 thick that
is a measurement it's not the absolute measurement but within industry when everyone agrees to take
a measurement in a specific way hopefully i would get the same measurement across any
one of these i might find around the country and the same goes true for leather and other things
i didn't even know these existed i didn't know these existed until i saw this on craigslist
and decided to purchase it yeah and here's the thing you don't actually you can you can
actually find out how consistent your material is too by running it at many different points
and measuring each one of those i'm noticing a variance across this piece when i get out to the
edges of about three thousandths of an inch for various manufacturing processes you might have a
a an acceptable tolerance of 3 5 10 20 000 i don't know it all depends on your manufacturing
process but this can help you get there in terms of being able to make sure that your materials are
consistent across a whole line but thank you for joining me for this awesome tool tip i'm going to
have to make a case for this i'm going to have to make a box that this sits in because it can't just
sit out just gathering dust slowly deteriorating no no no no no this has to be well treated plus
i think i may repaint the outside of this i've got a bunch of machines here with castings and
i'm thinking of painting all those castings the same color across my shop so that my shop when i
have casting based machines like my die filer uh or my machinist's vice that the color on
those castings is always the same i just haven't chosen that color yet that was way beyond what
you needed to know for this show and tell thank you guys for joining me i will see you next time