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!
On Mon, 18 Jan 2021 05:12:03 -0000 (UTC), John Doe
For just a few dollars (a small fraction of a stimulus check) more:
https://amzn.to/3iswLnc
0.001 mm / 50 microinch resolution.
Best regards,
Spehro Pefhany
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
calipers.)
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.
--
pyotr filipivich
"With Age comes Wisdom. Although far too often, Age travels alone."
-0000 (UTC) typed in rec.crafts.metalworking the following:
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
was old.)
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
Five.
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
the wall.)
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
Republic.
(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-)
--
pyotr filipivich
"With Age comes Wisdom. Although far too often, Age travels alone."
See also, shipping to the states. It is not worth (to me) the 30
bucks.
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.)
--
pyotr filipivich
"With Age comes Wisdom. Although far too often, Age travels alone."
For digital micrometers which I don't use regularly (It is too
cold to work in the shop right now) I open the battery compartment and
flip the cell upside down (so it does not feed the power to anything),
and pop the cap back on. This keeps it handy with the micrometer, but
also keeps it fresh. I also keep a spare cell in the box the micrometer
is stored in.
Most micrometers use the 357 and 44 sized cells (easy to
remember -- both numbers are magnum calibers) and they are available in
either alkaline or silver oxide variants. The battery life is much
better in the silver oxide (I prefer SR-357 cells) -- and I believe they
are also much less likely to leak and damage the micrometer.
Yes -- I also have pure analog micrometers too. Old eyes tell
me I need to wear glasses to use them.
BTW I also have one Russian 0-25mm micrometer. It is beefier than
all the others which I have or have used. I think the shaft is
8mm (about 5/16" instead of the more common 1/4" shaft on the
others. I guess that I would not be too upset at seeing it used
as a C-clamp. :-)
Enjoy,
DoN.
"pyotr filipivich" wrote in message
I kept a pair of cheaters in my tool book to go over the bifocals
in order to read the mic ...
-----------------------------
I keep bifocal safety glasses at each machine tool and my electronics work
areas.
https://www.zoro.com/mcr-safety-scratch-resistant-bifocal-safety-reading-glasses-20-bkh20/i/G0190723/
On Wed, 20 Jan 2021 07:54:27 -0800, pyotr filipivich
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
away).
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.
Best regards,
Spehro Pefhany
On Wed, 20 Jan 2021 22:43:11 -0000 (UTC), John Doe
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.
Best regards,
Spehro Pefhany
On Fri, 22 Jan 2021 01:16:53 -0000 (UTC), John Doe
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.
https://www.mscdirect.com/betterMRO/metalworking/what-spc-how-manufacturers-stabilize-machining-production
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.
https://ecatalog.mitutoyo.com/CRYSTA-Apex-EX-500T700T900T-PH20-Equipped-5-Axis-CNC-CMM-C1840.aspx
Best regards,
Spehro Pefhany
Axis-CNC-CMM-C1840.aspx
They have data output on some ordinary digital micrometers.
This one's on sale, Mitutoyo 293-340-30, $127 (USA)...
(Amazon.com product link shortened)
"Measurement data output function is available with a water-resistant
connection cable." (the cable might be extra)
On Fri, 22 Jan 2021 05:35:49 -0000 (UTC), John Doe
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.
Best regards,
Spehro Pefhany
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_s00?ie=UTF8&psc=1
Was planning to buy one of their new calipers, but my 0.0 mm resolution
Mitutoyo still works fine.