What tool - measuring crankshaft journals

Micrometer or calipers? Does it matter?

I'd use a mic. Mainly because I'm most familiar with a mic though. Correct me if I'm wrong, but I think a mic is more accurate?

Calipers to determine the gross dims: (Is it standard or undersize?) Mic to check before and after any machine work.

DrBoost wrote: I'd use a mic. Mainly because I'm most familiar with a mic though. Correct me if I'm wrong, but I think a mic is more accurate?

A micrometer is almost always more precise, but I have seen some very precise digital calipers. Accccuracy would come down to standard of manufacture and condition though.

No cloth tape stolen from the wife's sewing kit?

You don't measure diameter with it, you measure circumference and divide by pi. That way you get accuracy not down to the 16th, but all the way down to the 1/16pi-th! How could you go wrong?

Seriously, though, calipers are nice for gross measurement, but if you want fine accuracy, micrometers are better. Even the best calipers can give some pretty inaccurate readings with the greatest of ease. A little excess pressure and you work the play in the mechanism and you're throwing the measurement off.

mics are the best, just make sure you use oen with a lock and use the mic correctly too. slide it gently to get it right on the journal

MG Bryan wrote:

DrBoost wrote: I'd use a mic. Mainly because I'm most familiar with a mic though. Correct me if I'm wrong, but I think a mic is more accurate?

A micrometer is almost always more precise, but I have seen some very precise digital calipers. Accccuracy would come down to standard of manufacture and condition though.

Or... The user.

Can take a little bit to get consistent measurements. Not a bad idea to measure a good few times to make sure you can get same numbers if you haven't used a mic much.

RedS13Coupe wrote: Can take a little bit to get consistent measurements. Not a bad idea to measure a good few times to make sure you can get same numbers if you haven't used a mic much.

qft. measure everything three times and average it if or remeasure if they aren't consistent. its an acquired skill.

Also measure across the width of the journmal and at 45 degree intervals to check for taper and out of roundness.

Dan

If my father ever caught me using calipers to measure a crank he would kick my butt.