While I see that this topic is getting beaten to death, the list of on-topic uses for the ever-so-quick digital calipers appears almost endless and invaluable:
Doing axle work and measuring spacer thicknesses or axle / dropout width, priceless.
Measuring actual seatpost diameters and roundness, very useful.
Ditto, handlebars and stems.
Parts don't fit? Why? The caliper has the answer!
Shimming a derailer mounting bolt? Find the right washer pronto!
Derailer pully hub width differences? (.406", that'll do)
How wide, exactly, is this mounted tire?
How tall?
How worn out is this chain? Is it pitch-affecting wear, or harmless, unidirectional bushing free-play? (Measure @ rollers. Subtract one from the other, i.e. (5.2xx - 1.2xx)x(3333) = (%wear: Based on 0.5% allowable stretch, i.e. 1/16" per foot)
Which of these parts will give the best fit?
Is this hub French-threaded or not? Diameter and pitch comparisons.
Building a special freewheel? The caliper will allow you to sand down or grind a spacer to precise and uniform thickness!
Building a wheel? Measure the rim's depth to the top of a nipple quickly.
What godforsaken mid-section diameter are these spokes? Can they be mixed and matched?
Will this or that bolt bottom out in the hole before tension is realized?
Which o-ring or cartridge bearing will work here?
What is it about this saddle rail's diameter?
What size is this ball bearing?
What's the quickest way to sort out all my miscellaneous bolts and washers?
Just how weird is this cable housing's O.D.?
How much do I need to carve this cable's end to fit in the Huret shift lever?
Ergopower levers use smaller cable ends, so must measure after filing.
Is this frame's tubing metric? Is the paint thickness a problem?
Just how "ISO" or "JIS" is this spindle's taper? Chainline WILL be affected.
Need to scribe a line parallel to an edge, before cutting? (Is that why this caliper's tips are so sharp and hard and it has a locking screw?)
Did I grind this metal part wrong?
Will this hood fit this lever? (just kidding folks, or not)
The only improvement I would suggest to my now-10-year-old, $20 digital caliper, after many tens of thousands of uses, would be to incorporate my Casio watch's calculator into the body. My only problem with this one has been occasional battery weakness, but since having long ago lost the battery cover, a quick push on the lone battery always restores full power.
Since I mentioned hub threading, I am passing on this tip that an English BB cup (24tpi) makes a perfect thread guage for an English or Italian hub, while a standard 25.4tpi axle (i.e. Shimano and most others other than Campagnolo) makes a perfect thread guage for a French-threaded hub. (Thanks to Jim CycleArtist for steering me toward this solution)
I also must honorably mention my Park Spoke Tensiometer as one very useful tool for determining tensions of any diameter spoke.
David Snyder
Auburn, CA usa
Subject: Re: [CR] calipers
> Not to arouse the ire of our vigilante topic cops, in my experience, good
> vernier, dial and digital calipers have equal accuracy if you know how to
> use them. I'd venture that price probably gives better reliability, but
> for our purposes, the cheapest one serve just fine. I've had a vernier for
> 50 years, but over time have moved to dial and then digital as my eyes got
> older. They all have their pros and cons; I've found that dial calipers
> got dirt in the rack and started to skip. The battery on digitals would
> die. But I agree with earlier posts, spending under $20 on a digital
> caliper today is outstanding value.
>
> Brent Davis wrote:
>> For bicycles you only need to spend a small amount of money as there are
>> no
>> critical measurement that need to be accurate to greater then .001" $20
>> will
>> buy the tool you need and have in your box for the rest of your life.
>>
>> Learning what tool to use and when to use it is paramount to being
>> mechanically proficient. Vernier calipers have their place and are
>> somewhat
>> useful on bicycles but their limitations preclude them to either the wood
>> shop of or an extremely experienced professional. A dial caliper is far
>> more
>> accurate and better suited to occasional use and long term storage.
>> Digital
>> would be best used more often and considered less accurate then a good
>> dial
>> calaper unless you are willing to steap up and pay hundreds for an good
>> acurate digital caliper. You see comparing a $40 dial caliper to a
>> digital
>> is a mis match in accuracy.
>>
>> To really get precise throw out the calipers and get a mic.