Precision Gauge Blocks

[methuselah1]

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.

 

[Tim Wescott]

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.

 

[trlvn]

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

 

[ignator]

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.

 

[tornitore45]

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.

 

[trlvn]

After a bit of searching, I found tolerance info on a 26-leaf Mits set. +/- 0.0002 inches for leaves up to 0.007" thickness. Allowable variation increases to 0.00075" for leaves over 0.020" thickness.

https://api.sbsimpson.com/storage/documents/mti/950184.pdf
Even the lowest spec Jo block set is far more precise than that, right?

Craig

 

[ignator]

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.