In article , Dave Baker wrote:

Good god man, you've never lived.

You're not the first to say that. 8-)

Bore gauges are a must have if you do a lot of accurate i/d work. I have three
sets. The main one for engine bores is a Mercer 2" - 6" which reads to a tenth
of a thou.
snip
The other two sets get used a lot less. One runs 0.75" to 2" and the other goes
down to 0.5". They are both pretty old sets and read to a thou.
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What my lot would cost new these days I shudder to think.

For the 2-6", in tenths, from Mitutoyo, brand new retail price down the
street is $408.50 Canadian. The .750-2" would be about $310 (no perfect
match in ranges; that's an average of the prices of two reasonable matches).
The last one would be around $380. No perfect match there, either. So
those three sets would run you around $1100 Canadian, which is still a fair
bit when converted to pound sterling.

when you measure the gauge. Especially in soft metals like ally where the ends
dig in a bit as you rock them over centre. One of these days I must have a play
with a through bore and see how a T gauge reads compared to the Mercer.

The sets at work have been through the wringer. Too many apprentices with
no brains using them, I guess. The ends are worn flat. Probably tightened
up too hard before rocking them.

For through bores like engines and especially long bores the dial gauges are
the only way.

I am usually dealing with short bores, but I'm still seriously considering
picking the set up.

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Mike Graham | Metalworker, rustic, part-time zealot.
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http://www.metalmangler.com| Caledon, Ontario, Canada