Was planning to buy one of their new calipers, but my 0.0 mm resolution
Mitutoyo still works fine.
I need to know the dimensions of a rod, to stop guessing whether it's really
7.9 mm or actually 7.99 mm.
I would think such measuring devices jump to the next number when the zero
threshold is reached (going up) or crossed (going down). Will see!
Spehro Pefhany snipped-for-privacy@interlogDOTyou.knowwhat on Tue, 19 Jan 2021
15:00:40 -0500 typed in rec.crafts.metalworking the following:
One advantage to a non-digital micrometer - you can see if the rod
is almost 7.9mm or almost 8.0mm. (one of the reasons I like my dial
It is like clocks - a digital one will tell you what time it is,
right now." you get to do the calculations to figure out if you still
have time enough to do 'this'. With analog clocks, you can look and
say "I have a quarter / half /third of an hour to do 'this'."
Of course, it helps if you can read an analog clock.
That depends on resolution, not whether it's analog or digital.
Also depends on resolution, given limited space for its display.
With a digital display, only one dial is required, can't do that with
I can see as that would be useful. I have a calculator stuck on the
side of my mill so I don't have to subtract long numbers in my head
when I'm tired (and possibly end up cutting too much of the part
Don't own a pair of dial calipers, just vernier and digital.
But, as of a few weeks ago, I have DROs on the lathe and mill, so
digital maybe makes more sense.
I'm going to make a measurement with the micrometer, find the
difference from the desired measurement, and then move the tool some
number of tenths of a mm, say to take up half the difference and leave
enough for a finishing pass.
John Doe firstname.lastname@example.org on Wed, 20 Jan 2021 17:09:48
-0000 (UTC) typed >
I think the reason I go crank on analogue is that in another life
I am dealing with the measurement of time and distance, before the
adoption of positional notation and decimal fractions. Back when
everything was Integer Math, fractions of a unit were expressed in
ratios of whole numbers. And if you were Roman, in base 12 (1/12th was
the 'unit' for most fractions. E.G. 'half' is 6/12th) Relatively
'simple' but some numbers didn't work out E.G.. twenty two to seven
(22/7) is the ratio of circumference to diameter. But Pi is not a
'rational number. And I'm digressing badly.
It also depends on if you need a specific size, or a "go-nogo"
evaluation. And the precision required or needed. When I was turning
drill cores (for oil rigs) spec was for 8" diameter with +.250 -
0.000 tolerance.So I set a non measuring caliper at 8 1/4 inches and
when the band got to where this fitted "it's done".
Some of the other processes were not just on the order of +/- 001
but holding +/- .0004 over the entire 16 feet. "And that's why those
guys got the big bucks" On manual machines, too. (powered by belts
from a water wheel! "Why when I was a boy, we didn't have these fancy
dial calipers, we had to use our fingers!" Blah, blah. Yes, factory
Regardless of resolution, I can see if a measurement is closer to
N or N+/-[unit of resolution]. Is that 7.90001 or 7.99991?
IMHO, It doesn't matter the resolution or the number of decimal
places. I can interpolate +/- 1/2 the least significant digit. As
the saying goes "two plus two equals five for large values of two and
small values of five". I.E., 2.4 displays as Two, and 4.8 displays as
Yep. No sense putting a wrist watch on the wall - you can't see
the 'clock' let alone read it. (Heck, without my glasses, I can't see
With a digital readout - you get to do the math. Be that inches,
millimeters, hours, seconds, degrees (arc) or degrees (temperature)
miles per hour, furlongs per fortnight, or parsecs in the old
(On a side grumble, I've been looking to replace a garden thermometer.
Dial face, with two little arms which indicate high and low temps
since the last time they were reset. No longer made, but you can now
get a digital thermometer which you can press buttons until the min /
max temps are shown. Of course what was formerly accomplished at a
glance now requires an operator. And batteries. Which is another
"ought" I have against digital mics etc: batteries. Maybe if I used
them more often than once a year it would be different.)
It isn't like I am totally opposed to modern tech. I do
appreciate the digital temperature scanners at the club. I'd hate to
have to get a temperature reading the 'old fashioned way' with a
temperature sensing strip placed on my forehead. B-)
No, AFAIUI, it's for SPC (statistical process control) where samples
are measured, recorded, and mean/standard deviations and trend lines
calculated to figure out when things have to be jiggered before the
parts start to go out of spec.
Of course if you have a lot of critical measurements and a big budget
you'll use a coordinate measuring machine (CMM) that automatically
probes the parts with a little sapphire ball.
Many of the inexpensive Chinese ones also can have a cable attached to
output data (albeit with a different protocol than Mituyutoyo). It's
there to collect inspection data, as I said. Some folks have even made
crappy hobby DROs (mis)using them.
Gerry email@example.com on Thu, 21 Jan 2021 23:45:18 -0500
typed in rec.crafts.metalworking the following:
See also, shipping to the states. It is not worth (to me) the 30
Yes, I know I'm whining. Part of being an old fart is asking why
"digital" or "computerized" is deemed to be an improvement on what
works? How precise do the measurements _need_ to be? Like I've said,
I'm retired - most of frequently the answer the question "What time is
it?" is "Tuesday, mid morning." Same applies to measurements. Some
times I do need to know the size of 'this' to within a thou. Sometimes
... ten feet "plus or minus a quart." will suffice.
E.G., Do I really need to know that it is precisely 38.567 degrees
Fahrenheit in that corner of the yard when what I want to know is
whether it got below freezing?
Do I really need to know if this Ethernet cable is precisely 9
feet 11 and three quarters inches, if I just need to know "Will a ten
foot cable reach from here to there?" (And yes there have been
occasions when the cable is just a smidge too short, so something will
have to be moved.)
Spehro Pefhany snipped-for-privacy@interlogDOTyou.knowwhat on Fri, 22 Jan 2021
00:12:59 -0500 typed >>Spehro Pefhany wrote:
Or as my instructor as Tech School said SPC - "Slows Production
Completely". That old "we expect 100% perfection at all times" when
reality is a bit more imprecise.
When it works, it is wonderful. But ...
My sister once worked in a car plant. When I pressed her on what she actually did, she told me:
"I'm in quality control. I measure parts, and when they are out of spec, I report them. It actually works! One time I reported a part and they were on it right away. Within an hour they had changed the spec."