Gage Block Introduction – How To Use and Calibrate Gauge Blocks


Hello, I’m Jim Salsbury with Mitutoyo America Corporation and welcome to the Metrology Training Lab. in this episode
we want to discuss the truly amazing gauge block and talked about their use
and a little bit about their calibration I have to admit I’m a bit awestruck with
the gauge block these simple little blocks are something special each one
with their flat and parallel surfaces and with an accuracy of just a few
millionths of an inch we’ve used gauge blocks in previous episodes of the
metrology training lab but in this episode we get to understand them better
and appreciate their role as a premier measurement standard gauge blocks come
in sets like these and you can use these sets to build any length you need and
when done properly those lengths are more accurate than pretty much anything
else what’s even more amazing is that gauge blocks were invented over 100
years ago and they haven’t changed much in that time they have quietly played an
important role supporting all the incredible technologies that have been
developed since the early 1900s that’s pretty cool gauge blocks were invented
in Sweden by CEO Hansen he didn’t invent the idea of length standards but he
patented the idea of a set of blocks that can be used to build various
lengths and he was an incredible machinist
and his company was able to produce gauge blocks the tight tolerances that
allowed so many others to achieve new levels of accuracy in manufacturing some
people will refer to gauge blocks as Joe blocks in reference to Johansson who
Henson was also a pioneer in precision engineering and the standard reference
temperature of sixty-eight degrees Fahrenheit or 20
degrees C comes in part because he needed everybody to pick a common
temperature and when the top scientists around the world asked he recommended 68
degrees Fahrenheit because that worked well for him we have here an actual set
of Johansson blocks that one of my colleagues at Mid South America
collected you can see that your Hansen name and Sweden marked on the gauge
blocks the sets we sell today don’t look much different modern gauge block sets
basically follow his 100 year old patent during World War 1 the US government
became worried about the supply of gauge blocks to the United States from Sweden
along came a mr. W E Hulk who developed his own way to make gates blocks around
1917 he made them round with a hole in the middle to make them easier for him
to lap flat the square gauge block with the hole in the middle was derived from
hoax design and still today you can buy Gaye’s blocks in either yo Hansen’s
rectangular design or in hoax square design where tangler blocks are much
more common but some people like the square blocks in other episodes of the
metrology training lab you will see us picking either rectangular or square
blocks for various tasks for the interested viewer metoya has published a
little book on the history of gauge blocks you can download that for free
from our on-demand educational resources on our website
modern gauge blocks come rectangular or square in inch or millimeter sizes the
typical set includes lengths up to four inches but you can get long block sets
up to 20 inches and you can special-order gauge blocks up to 40
inches or one meter long the most common material
for gays blocks is steel mostly because the price is quite attractive other
standard materials include carbide and ceramics one of the big advantages of
ceramic gauge blocks is that they don’t rust however if you take care of steel
blocks such as wearing gloves when you handle them and putting light oil on
them when they’re stored they can last years even decades depending on how
you’re using them for this episode however I’m gonna mostly use ceramic
blocks the real reason is that these lights here are quite hot and my hands
sweat in these gloves and getting sweat all over steel gaze blocks is not good
practice now I can tell you some more advantages of ceramic gauge blocks but I
don’t want to sound like a salesman and that’s not the purpose of this episode
gauge blocks are sold by grades the grades to find tolerances for the
flatness and parallelism of the faces as well as the tolerance for the size
that’s marked on the blocks the grades apply whether the blocks are ceramic or
steel and whether they’re rectangular or square for example these three 1-inch
gaze blocks if they’re all grade 0 according to the tolerances of the
standard it would be plus or minus 6 millionths of an inch if this gates
block or all three is gaze blocks have been properly calibrated and found to be
in tolerance then I would know that the length is somewhere between the minus 6
millions and the plus 6 millionths of an inch I told you these things were
accurate if this was instead say a grade a s2 gates block the tolerance should go
from 6 millionths of an inch up to 24 millionths of an inch days
block grades are defined in national and international standards in the US we use
the American national standard for guage blocks asme be eighty nine point one
point nine you can also find the tolerance table in the mid-to Toria
catalog all manufacturers of gauge blocks sell them in grades in accordance
to the standards you should select gaze blocks based on your accuracy needs in a
calibration lab grade zero gaze blocks are quite common so that’s a brief
introduction to gaze blocks how do we use them gauge block faces are very flat
and very smooth the reason for this is that that allows gauge blocks to ring
together without using any adhesive gauge blocks can be brought together and
the flat smooth surfaces will adhere to each other without causing any damage when done properly the gap between the
two gaze blocks is somewhere around one millionth of an inch and when you’re
done they can be broken apart and reused over and over and any flat or smooth
surface will ring together steel to steel ceramic to ceramic even an optical
flat such as sown here I’ve rung together three different gauge blocks
rectangular steel ceramic and an optical flat all froze blocks are rung together
nice and tight that’s pretty needs the idea behind yo Hanson’s original
patent was the particular sizes in a set of gauge blocks they allow you to build
an accurate stack of gauge blocks to create any length you need so let’s walk
through the ringing process when you ring blocks you apply quite a bit of
force to avoid scratching your blocks it’s important they are clean it’s
important particularly for steel blocks to also make sure there is no raised
edge or burr or some sort of ding first I’ll use some des natured alcohol to
clean the block and then I’ll use this millet or Sarah stone to remove any
burrs this is sometimes called conditioning the block we’re not
changing the length of the block we’re just removing any high spots particularly on the edges I can use a
small Sarah stone like this using a push-pull technique or it can use a
large one like this and some people like to go in a figure 8 pattern and no you
don’t have to buy a midotaur Sarah stone but they do work well some people
recommend using a small grant surface plate and it’s hard to say how often you
need to condition your blocks it really depends on how you’re using them if you
were to very lightly slide a gauge block across a surface plate you may feel a
touch or hear kind of a scratchy sound that indicates a raised spots in those
cases you should do the conditioning I’m also not going to pretend to understand
the physics on why ringing works I’m an engineer I just need to know that it
works and how to do it in fact it seems to be a bit debated as to why it really
works we’ll leave that for the interested viewer what is it important
to know is that ringing works best with a very
very slight amount of light oil or grease on the gauge block faces we
really don’t use anything special in our lab for ringing we have these 20 year
old stamp pads lying around that have some wd-40 sprayed on them
yes wd-40 I can only imagine the comments that will be posted on our use
of wd-40 all you need to do is dab the gauge block in it and then wipe it off
on a dry cloth we don’t use any solvent here because we
don’t want to remove the oil we want just a little bit left on it now I’m
gonna bring these two blocks together and you do have to apply quite a bit of
force when you’re sliding one block against the other so I’m gonna set these
two up here and I’m going to try to slide this block against this block so
this is the kind of slide technique another technique is kind of that the
push and slide technique where you come from a side and go like this and then
you rotate the block as you’re pushing I’m not doing it now I’m just trying to
demonstrate how it’s done on the square blocks you can typically
use a push and twist technique in fact it looks like I just accidentally wrung
those two together alright so back to these two blocks here I’m going to push
on this while I’m sliding across here and you can see my thumb turn a little
bit white as I do that and if I did it right those two blocks are now long to
burn together pretty well when you’re all done using the wrong gauge blocks
you can just slide them back apart like this if you leave the blocks wrung
together for say several days or more it can become very hard to take them apart
so don’t leave them for too long ringing requires handling
the gauge blocks which may warm them up a bit so once they’re wrong you can
clean the outside surfaces and then let them sit for a little while to cool back
to the ambient temperature how long thus it depends on how much you handle them
and what your accuracy needs are if you want to see how well you can ring a fun
and easy test is to ring two blocks together that add up to the value of a
third say this 450 and 550 block which add up to one inch and we compare it to
a one inch block so we ring these two blocks together and then using something
like a high accuracy detector like this Mu-Checker, I can then compare the run
block stack to the single block now this test is not super accurate but it should
be good enough to see if you’re ringing skills are good enough to say calibrate
a micrometer our last topic on gaze blocks is their calibration in our
calibration lab here at Mitutoyo America we use really cool automated gates block
comparators but we have a manual version here in the metrology training lab so
let’s head over there and I’ll discuss some important topics on calibration
these blocks are usually calibrated using a comparison method this is the
master block and this is the customer block to be calibrated we set the
comparator using the master block and then measure the customer block in
accordance to be eighty-nine point one point nine the length tolerance for gays
blocks applies across the entire surface of the gauge block not just at that
gauge point and that a standard discusses the importance of checking the
size in a dish to the gauge point at all four corners this fixture here moves the
gaze block around such that we can measure the four corners quickly and
easily in order to state conformance to grade in accordance to the ASME B89.1.9 standard all five of these points must be in
tolerance gage block calibration practice in the United States is sometimes a bit
sloppy to save calibration costs some people have been convinced to go with a
single point calibration where the corners are not checked at all the only
time that’s acceptable is when you’re only using the gage block at that exact
measurement points and I think that’s pretty rare please be careful with
exposing yourself to calibration risks just to save a few dollars if you just
need a cert to show some auditor well that’s your business but if you really
care about quality to the calibration right I hope you learned a few things
about gauge blocks if you have questions or want to see something else on gauge
blocks please post your comments. Thank you, I’m Jim Salsbury, and I’ll see you next time from the Metrology Training Lab.

Posts Tagged with…

Write a Comment

Your email address will not be published. Required fields are marked *