On Fri, 24 Sep 2004 21:09:27 -0700, "AAvK" wrote:
Got one! Actually a really nice one made by Catic in HKC, of hardened
stanless. It is a proper design compared to the common General(T)
brand (has the oval cut-out window) and is layed out like this one, see
the graphic he http://www.rit.edu/~uphysics/Vernier...r/caliper.html
I just cannot "pick-up" on how to read it even from the lesson on this
page. It's inch increments are 1/40" at the smallest, someone told me
that is 0.025". I just don't get it with the decimals thing, but then again
I was recently diagnosed with ADHD, I'm a now a no brainer lol.
Thanks for the encouragement though, I would LOVE to find an easy
way to learn it.
Alex
Alex-
I'll give it a shot. first, grab a normal old tape measure or a ruler
or something, just for a sanity check. use it to check the marks on
the beam of the caliper. note that the inches are the proper distance
apart. then notice that the inches are divided up into 10ths instead
of 16ths like on a typical woodworker's tapemeasure. then notice that
each of those tenths is divided into 4 parts. so at this point we can
read the "full scale" units directly off of the beam to a resolution
of .025... which is to say one quarter of one tenth of one inch. but
the tool is meant to be read to a resolution of one thousanth of an
inch, or .001. so note that one thousanth is one twentyfifth of the
smallest marks that we can read directly off of the scale on the beam.
so what we have to do is divide those smallest marks on the beam into
25 smaller parts, which would be way too close together to read
without strong magnification. so what we do is read the thousandths
off of the OTHER set of marks, the ones on the moveable jaw. note that
there are in fact twenty five marks there. so first slide the jaw
closed. here we know that we are measuring a distance of zero inches.
note that the zero and the 25 marks on the vernier scale (the ones on
the moveable jaw) line up with SOMETHING on the beam. note that the
other marks on the vernier DON'T line up, though the ones at the ends
come close. so now let's pretend that we have something that is
7/8ths of an inch thick that we want to measure. 7/8" is the same as
0.875. so the 0 mark (our starting point) on the vernier is gonna
between the 8 tenths mark on the beam and the 9 tenths mark. there are
3 marks between, dividing that tenth into 4 parts, which in this case
are .825, .850 and .875. and the zero on the vernier will land right
on the third of them, the .875. so in this case we didn't need the
vernier scale other than to check ourselves. so now let's set the
caliper for say one and seven sixteenths inches (1.4375). actually, we
will have to settle for getting within a thousandth of that, because
this tool can't do the last decimal point. the one inch part is easy-
the zero on the vernier (on the moveable jaw) is somewhere between the
1 inch mark and the 2 inch mark. so 1.4375 is somewhere between 1.4
and 1.5 on the tenths marks, so slide the jaw over into that range.
between 1.4 and 1.5 there are 3 marks, representing 1.425, 1.450 and
1.475. What we want, 1.4375 is going to be somewhere in between the
1.425 and 1.450 marks. get the zero on the vernier (on the moveable
jaw) in between those marks. now shift your eye over to read the
vernier scale. here we have to decide how we want to round off the
forth decimal point. this caliper can read either 1.437 or 1.438 but
not 1.4375. just for kicks I'm gonna use 1.438. so what I do is count
up from 1.425 (where the zero is on the beam) to 1.438 on the vernier
scale, which gets me to the 13 mark on the vernier. (1.4)...25 + 13 =
(1.4)....38. so line up the 13 mark on the closest mark on the beam.
here's where it gets confusing, because the beam scale mark that the
vernier 13 is lining up with is not the mark we are reading. we are
reading the location of the zero on the vernier (on the moveable jaw)
for the rough measurement (within 25 thousandths) and the vernier
scale for the fine measurements (within 1 thousandth), ADDING THE
VERNIER READING TO THE BEAM READING.
aack. that was terrible. a lotta buncha words to get a simple concept
across, and I'm not sure I even got there. the first few times it will
be a challenge. I'd recommend getting a set of feeler guages and
practise measuring those- they'r very accurate, cheap and have the
decimal thickness etched right on them. after a while it gets to be
second nature to pick the numbers right up. the vernier caliper is a
great tool- very simple, very reliable, no batteries or digital
displays to go bad, no gears and dials to wear out- just takes a
little cypherin'