What is it called and where (USA, preferably online) can I buy a starter tool for measuring the outer diameter of small diameter rods and whatever other shapes? I'd like something more accurate than looking sideways at a ruler. Thanks.
Carla's recommendation is good, but if you want precise measurements, buy a micrometer. They aren't as versatile as calipers, but much more precise. Let your needs make the decision for you.
Harold
(...)
Micrometers are more accurate than calipers, too.
--Winston (GD&R)
You have already gotten god advice. Think about the amount of precision you need means:
Squinting sideways at a ruler= the actual diameter plus or minus
1/16" or so. Cheap dial caliper= the actual diameter plus or minus a couple of thousandths of an inchDecent micrometer= the actual diameter plus or minus a couple of ten thousandths of an inch.
Pete Stanaitis
---------------------------
John Doe wrote:
Holy moly.
Planning to order an inexpensive micrometer (Empire Level 2780).
Ugh. "Die cast metal frame" would make me nervous. Cheaper and probably better:
eBay has a like new Starrett 0-1 with box, wrench, and paperwork for about $4.04 incl. shipping - for auction. Item number: 170267391345
Digital caliper -- quick and easy to read -- but not quite as accurate. Readout typically to 0.0005" (or 0.01mm).
These typically can measure things up to 6" diameter (or long or whatever). Keep spare batteries on hand for them. They don't always last very long. And turning it "off" does not really turn it *all* off
-- just the display part, not the measuring part.
Micrometer -- more accurate -- and with the Veeder-Root style display on that one, just as easy to read. One to cover the size you requested will cover from 0.000" to 1.000". You need extra ones to cover 1-2", 2-3" and so on, but for what you requested, one is sufficient.
A cheap micrometer can read to 0.001". A more expensive one can read to 0.0001" (with the use of a vernier, which you will have to learn to read), It looks as though this one has the vernier -- you won't get the 0.0001" readings from the Veeder-Root readout.
And it is a little tricky to get the readout and the thimble zeroed at the same point.
Get a good electronic digital one, and you get direct readout to
0.00005".
O.K. Electronic digital -- the readout looks as though it only goes to 0.0001" -- but that may be switched into mm mode, in which case it should go to 0.00005" in inch mode. Looks as though the thimble on this one is in mm not inches.
Still -- any of these will do what you requested.
Note that there are also (older) versions of the calipers in the first list which don't require batteries.
The original version was the vernier caliper -- hard to find now, except used ones on eBay. They measure to 0.001" but you need to learn to read a vernier. Some have dual scales and verniers, and can read in both inch and metric.
The next one is the dial caliper in which a needle rotates around a dial (usually covers 0.100" per rotation). Most of these are solely inch or solely metric, though there are some with a weird mix of two needles geared to rotate properly, and two scales. I personally would not use one of these.
As for measuring "whatever shapes" -- you will probably find some shapes which you can't measure with any of these. Examples include three and five flute milling cutters. There are specialized V-anvil micrometers for these tasks -- two different ones, depending on the number of flutes.
Good Luck, DoN.
I ordered a Mitutoyo MyCAL Lite 700-113 Digital Caliper 6" off of eBay. Whether or not it's satisfactory, I'm sure it's better than nothing (assuming the auction was legitimate). Thanks to the replies/advice/keywords.
I plan to use it for grinding a cordless tool motor gear to fit snugly inside of an aluminum tube. The caliper might not be very accurate, but I suspect it will be accurate enough to measure and correct the results of my grinding.
Apparently there is some disagreement about measuring the evenness of a cylinder best with either a micrometer or a caliper. Seems to me that a narrow jaw you can slide along the rod would help give an idea of which end is wider. But I suppose you could also modify a typical micrometer to give it a thin jaw.
You can buy mikes with thin anvils, and mikes with replaceable anvils of various types. But you won't find many, or any of them in the low-priced category.
Not knowing how closely you have to fit that gear in the tube I wouldn't judge which is better for you, but there are several reasons that mikes are more accurate. The narrow jaws of a slide caliper are not necessarily a problem, except that you have to be extra careful to keep a caliper perpendicular to the work, or you'll get some cosine error. However, that's mostly a problem when you're using the beveled outer tips, not when you have a part well inside of the jaws.
Calipers are more lightly constructed and they spring; the trick is to be consistent in applying pressure. This is easier to do with a mike.
But if you're doing work of average accuracy and you only want to buy one tool, a caliper is far more versatile. When you get into precision work and close fits, the mike usually will serve you better.
If you think of this as your *first* tool, rather than your only one, you won't go wrong with either one -- because you'll want the other one before long.
-- Ed Huntress
Yup, it has proven very useful, from time to time.
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.