Metrology 101

[The Liberal Arts Garage]

All though it is implied, do not fail to clean all surfaces and tools ( Including
your own moving parts)........BLJHB.

 

[The Liberal Arts Garage]

Jim, thank you so much for posting this. I am eating it up! I copied and pasted it into my personal notes (with your name there, I always do that)

... I am also waiting for the next installment! You have fans now, watch out!

Bernie

. Please don't forget "stiff". calipers-- practically free at yard
Sales etc. Learn a "nice touch". Clean, delicately file as needed, adjust tension
to smooth, not sticky, motion .practice on known standards. Sizes unlimited !
Old Fart advice from.........BLJHB.

 

[T Bredehoft]

Measure drill bits to size... only on the cutting end. half way down the drill they are smaller, only by a few thousands, but smaller.

 

[Wreck™Wreck]

Twist drills have back taper, also have never had an issue with vernier calipers except for the 40" Mitutoyo where I work which is entirely to heavy (-:
Screw machine drills are short because the machines only make short parts mostly.

Gauge blocks are rather expensive for home use, a nice alternative are on size steel dowel pins which are within .0005 of nominal diameter when bought from reputable manufacturers and annular bearings are good for larger diameters as they are good for less then .001 on the ID and OD

 

[Bamban]

In my world, this is the differentiation between accurate and precise

 

[atunguyd]

To me the accurate not precise is incorrect. The target should show holes in the centre but the holes should be excessively large or not round. The shots are accurate but the precision of exactly where they hit is rough.

Sent from my SM-N920C using Tapatalk

 

[Tony Wells]

Mathematically, the center point of the average circle (overall position of the represented circle) is not too far from bullseye, therefore is accurate, but the spread is all over the place, and therefore not precise. The holes themselves are another feature and not germane to the definition. I believe this same reference is used in an example in Wiki, FWIW

https://en.wikipedia.org/wiki/Accuracy_and_precision