Precision Gauge Blocks

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A bearing race makes a substitute that is probably more than sufficiently accurate for home use.
Absolutely! They also make very fine circular parallels- but although they're not bad, two races of the same type may not necessarily be the -exact- same width. The "important" tolerances regard the diameters.
 
Gauge blocks are great for measuring groove widths -- like those piston ring grooves you cut that were apparently smaller than the cutter, over on the other thread.

Basically, if you get them, you'll find uses for them.
 
A bit of an offshoot question...

How precise are feeler gauges? I have multiple sets of feeler gauges even though I've never bought any new. They all came in auction box lots. Of course, each leaf is labelled as being a certain size but are there "A" grade sets that are spec'd to a higher tolerance? Is there a typical +/- for common sets?

Just curious,

Craig
 
A bit of an offshoot question...

How precise are feeler gauges? I have multiple sets of feeler gauges even though I've never bought any new. They all came in auction box lots. Of course, each leaf is labelled as being a certain size but are there "A" grade sets that are spec'd to a higher tolerance? Is there a typical +/- for common sets?

Just curious,

Craig
The problem I've encountered with feeler gauges, they are punched from sheet stock, and typically have a raised edge. They work OK for setting engine tappets, as the central part away from the edge is used. I have old used feeler gauges as well, that were used back in the day, and are all dented up from being used to set the valve clearance. I think this happened when the engine was running. :)
 
Considering that feeler gauges come in 0.001" interval the need to distinguish 0.003" from 0.0032" seems purely academic. Still I would guess the manufacturing ability to grind to thickness within 0.0001" is achieved without special effort. Bends, dings and buggered edges are another matter.
 
Even the lowest spec Jo block set is far more precise than that, right?
+8/-4 microinch max for grade 3, less then 1 inch. At least what I found. Seems the set I have, I've seen numbers that range +/-30 microinch on the calibration sheet included, so this must be an economy set of blocks.
 
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