Micrometer time!

My only micrometer.
formatting link

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!
Reply to
John Doe
Loading thread data ...
For just a few dollars (a small fraction of a stimulus check) more:
formatting link
mm / 50 microinch resolution.
Best regards, Spehro Pefhany
Reply to
Spehro Pefhany
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 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.
Reply to
pyotr filipivich
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 analog.
Reply to
John Doe
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
Reply to
Spehro Pefhany
The lathe uses output from a micrometer?
Reply to
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
Reply to
Spehro Pefhany
John Doe snipped-for-privacy@message.header 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 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-)
Reply to
pyotr filipivich
Is that what the data output on some micrometers is for?
Reply to
John Doe
See: Lee Valley - Item AB803, Min-Max Thermometer
Reply to
Gerry
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.
formatting link
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.
formatting link
Best regards, Spehro Pefhany
Reply to
Spehro Pefhany
Oh! Maybe that means "digital readout".
They have data output on some ordinary digital micrometers.
This one's on sale, Mitutoyo 293-340-30, $127 (USA)...
formatting link
"Measurement data output function is available with a water-resistant connection cable." (the cable might be extra)
Reply to
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
Reply to
Spehro Pefhany
Gerry snipped-for-privacy@yahoo.ca 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 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.)
Reply to
pyotr filipivich
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 ...
Reply to
pyotr filipivich
Oh. So the micrometer data output doesn't go to a lathe or a mill.
Reply to
John Doe
.... When it works, it is wonderful. But ...
Reply to
Jim Wilkins
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."
John
Reply to
John Halpenny

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.