Is there a method of measuring the exact mm of a shaft without a caliper?

J

justinb386

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I am curious if anyone knows of a method of measuring the exact mm of a shaft without a caliper?

I am guessing it is not possible to get an exact measurement, but just curious if anyone knows of a way.

I been wanting to buy a good digital caliper for awhile, but even a not so good quality one (that I do not think does a good exact measurement) costs $30 at the auto store.

Thanks
 
justinb386 said:
I am curious if anyone knows of a method of measuring the exact mm of a shaft without a caliper?

I am guessing it is not possible to get an exact measurement, but just curious if anyone knows of a way.

I been wanting to buy a good digital caliper for awhile, but even a not so good quality one (that I do not think does a good exact measurement) costs $30 at the auto store.

Thanks
Click to expand...

You can take a strip of paper and warp it around the shaft and mark it to get the Circumference. Lay it out on a ruler and then just do the calculation.The the formula is, Diameter = Circumference divided by Pi
You should be pretty close.

I just tried it that way and done carefully I came within .002 compared to the micrometer. I have a ruler with 64 of an inch marks. It fell right in between two marks so I estimated them at 128 th of an inch and it was right on.
 
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justinb386 said:
I am curious if anyone knows of a method of measuring the exact mm of a shaft without a caliper?

I am guessing it is not possible to get an exact measurement, but just curious if anyone knows of a way.

I been wanting to buy a good digital caliper for awhile, but even a not so good quality one (that I do not think does a good exact measurement) costs $30 at the auto store.

Thanks
Click to expand...

Pi = 3.14159.....

Every cell phone on the planet has a calculator, as does every PC with Windoze...
it even has a "scientific" version with a PI key.

Dale(unparalleled Mathematical genius in residence)
 
Like Jimmy said, even the cheap digitals will do the trick or even cheaper, the dial calipers.

I have one in case my digital runs out of battery power.

Muellers and a couple of other places sell the plastic cards with the holes in them.

Place you shaft in the proper hole to get your diameter.

They don't work well if you have a shaft diameter that is in between the regular pre measured holes.

For 10 bucks, you will eventually get your moneys worth out of a cheap caliper.

The digitals can toggle between decimals, (thousandths) and millimeters.
 
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justinb386 said:
I am curious if anyone knows of a method of measuring the exact mm of a shaft without a caliper?

I am guessing it is not possible to get an exact measurement, but just curious if anyone knows of a way.

I been wanting to buy a good digital caliper for awhile, but even a not so good quality one (that I do not think does a good exact measurement) costs $30 at the auto store.

Thanks
Click to expand...

The ones at auto store are more the accurate enough. I use mine for reloading pistol and rifle ammunition. I wouldnt use it if I thought it was inaccurate.
 
How about you place the shaft on a table, put something on either side of it,preferably flat, scrap blocks of wood, old vhs tapes :) I dunno anything. Then measure between them with a ruler. How much more precise would you need it?
 
The most basic China made digital calipers out there are more than accurate enough for cue measuring. There are 14 pages of them under $10 shipped, new, on ebay.
 
better than anything is a drill measuring guide available at most hardware stores for a couple of bucks. it is holes drilled in a card, so you put it over the shaft and the opening that fits is it. this way its easy to tell all the way down the taper as well.
 
justinb386 said:
I am curious if anyone knows of a method of measuring the exact mm of a shaft without a caliper?

I am guessing it is not possible to get an exact measurement, but just curious if anyone knows of a way.

I been wanting to buy a good digital caliper for awhile, but even a not so good quality one (that I do not think does a good exact measurement) costs $30 at the auto store.

Thanks
Click to expand...

Go to Harbor Frieght Tools ( if the have one in your area ) and u can pick one up for like $5. They are a generic brand but work just fine. If not in your area they do have mail order too, good luck.

Sorry guys did not read thread first lol
 
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pdcue said:
Pi = 3.14159.....

Every cell phone on the planet has a calculator, as does every PC with Windoze...
it even has a "scientific" version with a PI key.

Dale(unparalleled Mathematical genius in residence)
Click to expand...

Sigh...

Once again AZB is baffled by arithmetic.

I am just grateful the OP didn't ask how to determine the distance
from Boulder to Birmingham.
 
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Jim Baxter said:
NO !!!!!!!!!!!!Digital Caliper , less than 10 bucks , at Harbor Freight . Also e-bay . Jim
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This is exactly right IMO. There is no other method that will be as quick, or as accurate, as what you can get with even the cheapest digital caliper that costs around $7 shipped to your front door. So unless $7 is a prohibitive cost, that would be your best bet, by far.

Here is one in carbon fiber/plastic (all the caliper you need for your purposes), $6.98 shipped to your front door:
http://www.ebay.com/itm/Carbon-Fibe...620?pt=LH_DefaultDomain_0&hash=item20e2f244d4

For $10-12 shipped to your front door you can get one in stainless steel (which you don't really need for your purposes) and maybe even for less, I didn't really look around. As mentioned above, they are also available at Harbor Freight in this same price range.
 
You get some cotton,( I used low stretch fishing line not nylon) wrap it around the area so that you can tie it/secure it ,and then get enough to get at least 10 wraps. Mark a line across the warps of line, I used a pencil to mark it. Then cut the line at the 1st mark closest to the spool(last turn on the diameter).Unwrap 10 turns and then cut on the line for the last wrap to be un wound( the beginning of the 10 turns). Measure on a metric tape measure.
My cue ferrule is actually 11.50 mm in diameter, My length of line measured 361mm.
361 divide by 31.4159 is 11.49 so it is very close. A 1mm length measurement error represents only 0.03mm in diameter error. About as accurate as cheap calipers.

Neil
 
As others have mentioned, if there's a Harbor Freight in your vicinity, that's your best bet. eBay from China is the same thing. They're pretty useful devices in general, so it's not a bad investment at all. Or when you start to get really bored, and think about things like the thickness of various dollar bill sizes or coin diameter differences...
 
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