Metric micrometer what t buy?

Still some bargains out there, I picked up this 0-1" Moore & Wright for £7.50. It was pretty dirty when it arrived but a really good clean got rid of most of it though not all of it. Its very smooth with a good ratchet, the mating faces are as good as new and its spot on zero and accurate to a few slip gauges I tested. Came with a case the spanner and a clip on pointer/indicator, not bad for less than a tenner.

Surely depends on what the micrometer is for?

• I don't need an Imperial Micrometer at all. (Nasty things involving lots of silly conversions!)
• If it's really got to be accurate, which is what they're for, best to buy a new one. Maybe with a certificate.
• Buying second-hand is pot-luck, anything from scrap to 'as new'. As an inaccurate micrometer is junk, why risk it.

Buying pot-luck needs more analysis. Shame on you if it was bought expecting it to be in good order. (Some have been used as G-Clamps). Top-marks if it was bought for the adventure, cheerfully expecting it might have to go straight in the bin, or collected for nostalgic reasons.)

Assuming it was bought to be used, is it logical to buy a precision measuring tool that has to be checked with slip gauges before it can be trusted? I'm glad the Moore & Wright passed, but I bought an ordinary micrometer new, nothing special about £25, that was reliable out-of-the-box.

Putting it another way, would you care to have an elderly worn-out silly old duffer in your workshop. I'm sure a quick clean and polish will have me in perfect working order, at least for any Armchair Engineering needed...

Dave

Well it obviously didnt meet with your approval Dave but it met with mine..

Silly conversions, what silly conversions..? I am quite happy working with metric or imperial and most of what I do is metric, my locos are metric. When it comes down to tight dimensions/tolerances etc I instantly see thousands in my head better than I see parts of a mm but that is just me, hence an imperial micrometer.

It didnt need to be checked against slip gauges but I thought I would and I would have done the same for a new measuring tool.

"Shame on me" and "why risk it" well having spoken to the previous owner I knew it would be good and at £7.50 what is there not to like.

Ron

If You buy new and do not inspect, You might not get what You expect. Sorry I'll get Me coat

Wouldn't worry me, but no touching the machine tools without strict supervision!

Oh dear, I've got lots of micrometers, imperial and metric, and I've never bought a new one in my life. Only had one duffer, a 4-5" micrometer bought on Ebay that was about 15 thou under-reading. Sold it back on Ebay and got my money back.

Andrew

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Quire right too Ron, you wanted it, not me!

30 examples of silly conversions have been carefully engraved on the side of your lovely micrometer. Happens to be 16ths and 32nds, but engineers once had to deal with thirds, quarters, sixths, eighths, fourteenths, 64ths, 128ths and others. How many inches and thou in one third of 5' 5¾". How many thou in 1/6" + 3/128" ?

Thou (also known as mil & points) are a handy way of defusing one of the Imperial Systems less desirable features - fractions! Fractions may make easy calculations easy, but they also make hard calculations much harder. For that reason thou have become almost universal in Imperial engineering, but no-one else uses them.

Metric goes a step further by completely dumping the likes of fathoms, yards, feet, inches, and fractions. Doing so removes the need for many unnecessary and error prone calculations.

I suspect half an hour doing serious engineering sums would cure most Imperial Fanboys! What's the volume of a super-heater tube 40' long, 5⅛" diameter and 7 s.w.g thick? If the tube is made of steel weighing 0.283 lbs per cubic inch, how much does it weigh in cwt? If the coefficient of expansion of steel is 0.000007, how long will the tube be at operating temperature 420°F?

Each to his own, I'm only stirring the pot for fun.

Dave