hi I'm Mike Grosenbach product specialist for distributed products at Mitutoyo
America Corporation today I'm joined by Dakoda Pollitt who is a CNC machining
student in the Chicago area I guess and we get a lot of questions at Mitutoyo
concerning inside measurement inside diameter measurement and ID gauges
there's a lot of different gauges out there depending on your application
accuracy requirements and budget and all these choices can get overwhelming so
today we're going to give a little bit of insight on the different types of
gauges with a focus on to contact style gauges in hopes of eliminating some of
this confusion and today we're going to talk about an overview of how they work
the setup and the usage of these types of gauges so the first gauge we'll talk
about our telescoping gauges so I assumed you've used these before yes
actually my personal set that I use in class alright so basically what these
are they're two contacts that are spring-loaded so you can put it down
into the bore and inside diameter and then once you've picked up the diameter
you can lock it down with this nut that's set into the handle so for
example how would you use this to measure a cylindrical bore like this
first it kind of going at an angle then I rock it back and forth until I kind of
feel it grab and then I lock it down okay and one of the things to check with
this is after you've locked it down swing it back and forth again to make
sure that you've picked up the actual diameter if you feel like catching then
that means that you've probably locked it down at a far false large reading so
you're not reading you're not measuring the actual diameter of the of the bore
and after that we're gonna take it to our micrometer and measure the
telescoping gauge so here you're going to measure it in different places and
make sure that you're picking the the maximum reading of this of this bar as
it's being setting in the micrometer if you're measuring something that's
smaller if it's at a slight angle you're going to get a smaller dimension which
is going to be inaccurately small
so our teacher told us to do it three times then get the average so I'll do it
the second time okay so these are fairly common gauges - they're in a lot of
different shops they're really inexpensive and after you've taken it
out measured a bore you measure the the telescoping gauge with a micrometer
which every machine shop is going to have it's a good idea to do it three
times just because it is a little bit trickier there's a little bit more feel
to it so when you're making sure that you're picking up the ID measurement of
the bore yeah so we added eight ten thousandths on this one eight ten sire
okay so and as you're seeing here - there's a lot of potential sources of
air with these there's no live reading when you're putting it into the inside
diameter so you do have to put it down and get a feeling for it lock it down
and measure it and because it doesn't have a live reading you do have to
measure it and verify your measurement and the gauge is also then measured by a
micrometer which is another source of error in itself and it's slightly
difficult to line up the telescoping gauge between the contact surfaces of
the micrometer if you don't have it perfectly lined up again you're gonna
get a false small reading on the telescoping gauge is there a more
accurate way to measure other than the telescoping gauge absolutely the next
step up would probably be the dial bore gauge have used one of these before
I've not what makes it different than the telescoping gauges well basically
what this is it's a comparison gauge with on the head you've got a solid or
fixed anvil and a spring-loaded anvil that translates the motion up through
the bore gauge to the dial indicator that's located at the top there's also a
spring-loaded centering mechanism here which tends to Center itself in the bore
and normally these would be set up with a master part or a setting ring or a
micrometer or even a bore gauge setting tool one reason why it's better is that
you can actually see the minimum reading being picked up on the dial face and
it's easy to get a feeling for where the actual diameter is in the bore so let's
go ahead and set this up
so we've set our micrometer to our nominal which in this case is three
point zero seven so when you're setting up between the the faces again you've
got these two spherical faces on the bore gauge and the two flat faces on the
micrometer so you're going to want to make sure that once they're placed in
between the faces that you do a sweep back and forth to make sure that you're
picking up the minimum reading and then also twist the head back and forth to
make sure that after you've picked up the min reading one dimension you you're
picking up the minimum reading and the other as well okay okay so let's go
ahead and measure this board here then all right so I'm kind of doing it
similar to the telescoping gauge similar telescoping yeah so you're gonna put the
gauge in swing it back and forth and see what the the minimum reading on the dial
face is so it's on the eight graduation okay on the 8th graduation so this is a
one tenth graduation indicator so eight graduations would equate to then eight
ten thousandth of an inch in thousands of an inch and it's on the plus side of
the of the zero point so comparison type gauge zeroed out
eight tens high so that means that you'll add that on to the nominal of
what you set it up with so it'll be three point zero seven zero eight inches
for the actual bore diameter let's say we wanted to see the out of round of the
board to see if there was any OV ality to it for example so let's go ahead and
if we put it in and now rotate it about ninety degrees as a sample from where we
previously measured it and then take another measurement of the bore yeah so
this one is at nine ten thousand this time okay so it's nine ten thousand so
this would gives it since this is one ten thousands different from our
previous measurement there's about one tenth out of round four this bore so
this was definitely easier to use is there anything else I should be kind of
looking for while using it yeah absolutely it is still a bit subjective
because you do have to look at the minimum reading on the dial display so
different operators could look at that a little bit differently one could see
eight tenths one could see nine tenths or that it's in between there is also a
little bit of parallax error between the needle and the dial face and also the
grads could be misread this is a one tenth graduation indicator but for
sample if you had a 5/10 graduation indicator if you read five graduations
on that wrote down five tenths actually that was two and a half now
of variance between those also it's a mechanical gauge so the data off of this
would need to be written down and maybe typed in later which also introduces
transcription errors so how do you overcome some of the challenges we face
with the dial indicator absolutely one way of doing that would be to use a
digital indicator this one specifically is designed for bore gauges so what's
nice about it is has three presets and it also has a minimum hold mode so once
it's in the bore gauge you can put it down in the bore hit the start button
and sweep it and it'll automatically pick up the diameter of the part it also
has a tolerance mode where you can at a glance see if it's in or out of spec
high or low and it has output so if we wanted to send the data to a computer
you could do that wired or wirelessly so let's start by setting this up in a
setting ring
so you put it in hit the start button and then sweep it by the diameter after
it's picked up that minimum reading code and hold down the preset button for a
couple seconds and we've already entered the preset value of the setting ring
which is three point zero zero zero two five let's go ahead hit OK and now the
bore gauge is set up it has the setting ring value automatically assigned to
that minimum reading or bore gauge reading so now we're ready to measure
the bore so we'll put it in measure as normal go ahead and hit the start button
to start it off okay you'll sweep it by the peak value I noticed that as those
same analog bar as the dial indicator exactly so it'll still give you a visual
representation just like a dial indicator so it also helps with the
feeling of the gauge she showed me a couple different styles of the two point
gauges are there any other different types yeah absolutely there's also the
three contact style which have three pins in a head these are a direct
reading type gauge they also have a longer stroke than a typical bore gauge
and these are typically used for tighter tolerances and they tend to seat
themselves in the bore with just minor positioning there are two types of these
gauges the Mike head style as well as the spring-loaded style they use the
same measuring heads but the Bora Matic is nice because you can use in different
orientations it's very quick so if you wanted to take a measurement here you
can also rotate the face to measure in a different orientation some people though
do still prefer the micrometer head style because of stability okay so once
you try this out on this board measure this alright
so you see that he's positioned it in the bore and with minimal posit
repositioning he's already measuring the inside diameter thanks Mike I learned a
lot today people have questions or suggestions for future videos what
should they do for questions and suggestions use the comments below or to
schedule a demo call 888-MITUTOYO or visit www.mitutoyo.com