Micrometer vs. caliper?

I am considering buying either a micrometer or a caliper for measuring things like rotor wear and for general usage.

Have any of you Pelicanics (I know, I know) found either of these to be more useful in everyday use? Secondly, is there an internet site that you might recommend for buying such a tool?

As always, thanks in advance for sharing your wisdom.

Rod Walter
'88 911 coupe

Rod,

I have found a 6" dial caliper to be more useful because of the much wider range of measurements, 0-6" rather than 0-1", and the inside/outside capability.
www.harborfreight.com has a stainless steel 6" model for $19.99.

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Warren Hall
1973 911S Targa

Most shops I've dealt with use a micrometer. One reason is sometimes the rotor develops a ridge at the outer edge that would interfer with a caliper getting a true measurement. Sears has a fair quality micrometer for $20.

Originally posted by Rod Walter:
I am considering buying either a micrometer or a caliper for measuring things like rotor wear and for general usage.

Have any of you Pelicanics (I know, I know) found either of these to be more useful in everyday use? Secondly, is there an internet site that you might recommend for buying such a tool?

As always, thanks in advance for sharing your wisdom.

Rod Walter
'88 911 coupe

Hi Rod. They are two different tools. I use my calipers for a bit of everthing when precision is not the most critical(+/-.001). A decent caliper will allow 4 way measurment 3 are pretty useful. OD ID and depth. A micrometer is strickly OD but with a little practice it is not to hard to split .001 10 ways or .0001 accuracy.
I do very highly recomend getting a digital/ electronic caliper so you get direct readings in inches or metric at a push of a button. I have made very expensive mistakes with simple misreads on dials and mics,it does happen to the best tool makers. I would spend a few bucks and get a high quality caliper, they should be accurate over their entire range. If I had to pick a best/affordable, I would go for a 6" mitutoyo digimatic. The perfect high end match for a porsche is a Mahr,made in Germany and very accurate with a great feel. The mits should be a little more or less than $100 and will last many lifetimes.

david 89 turbo cab

i agree fully with 5axis. i have the exact same Mitutoyo digimatic electronic calipers and i find them to me extremely useful, and accurate!

get one if you can find one. they really are a lifesaver!
http://www.newmantools.com/mti1.htm

obin

I agree that they are completely different tools. Years ago when I was machining everyday, my 70 year old mentor discribe the diffrence as:

Calipers are like a tape measure, an everyday cost effective tool that you can use in a varity of cirumstances for accurate yet rough measurements

Micrometers compared to calipers as a tape measures compare to a steel lay out rule, they are used when you need precision and accuracy.

I keep my calipers in the tool chest in the garage and use them all the time, my mic set is stored in my shop and rarely required except during engine or trans building.

Todd

Well, I was leaning toward a micrometer but having read your posts I now believe that calipers would be more versatile and probably of sufficient accuracy for most of the uses to which I might put it. Thanks!

I am curious about the rotor lip issue. Do some calipers have offset (?) "jaws" that would permit accurate measurement over the edge of a worn rotor?

Rod Walter
'88 911 coupe

Hi Rod the typical method to overcome the "lip" would be to use spacers(washers or something) of a known thickness then just subtract. This will induce a bit of stack error but not enough to worry about.
these guys have mitutoyo 6" digimatics for $98 http://www.use-enco.com
have fun P car wrenching
david

Hi 5Axis! With a digital caliper you can measure the cheater blocks and "zero" the calipers then measure the actual part with the cheater blocks and the caliper will display that dimension.

George

83 911SC Cab/Euro

Thanks, 5axis and Machintek. I'll be searching for calipers soon to add to my tool box.