17mm Spanner Dimensions

[GC8]

What measurements should I expect from a decent 17mm open ended spanner? Ive been measuring the opening and the base on both reasonable quality and cheaper alternatives and I cant find a concensus.

Some are 17.34mm at the opening whilsts other are 17.12mm, with everything in between and no division between 'good' and 'bad'.

[mr.man]

I suspect you've just acquired a Digimatic Caliper and are looking for things to measure.

[GC8]

You are not right, but youre not that far wrong. Ive had it for a while and I measure all manner of things.

I have always presumed that tolerance is one of the things that alter with tool quality and I thought that measuring a selection of qualities would give a consensus, but it hasn't unfortunately.

[shoehorn]

Take a selection of say 10,13,15 17 and 19mm nuts and bolts from different vehicles and you will find that they are all slightly differing in size when it comes to accurate measurement.
Spanners and sockets specifically are made slightly larger to accommodate the difference in manufacturing tolerances across an infinite amount of fastener manufacturers.

[steveo3002]

ive got a cheapo digi caliper and my snap on spanners are up xx.35 mm

seem to work good and ive had them years so must be right , id imagine cheapo fasteners will vary more

[GC8]

Thanks. I will measure the set which has the xx.34 measurement and see whether theres any continuity between the sizes.

[Rollcage]

Great, do that!

[honestbob]

And with the internal points you could check out all the sockets for consistency
in your tool box.

[Dave^]

honestbob said:

And with the internal points you could check out all the sockets for consistency
in your tool box.

Not forgetting separate measurements for each pair of flats...

[GC8]

Youre being silly now. Im trying to establish whether measurement/tolerance can be used to identify decent spanners (or poor spanners with a high price tag).

[phillpot]

Open end spanners should be a "last resort" after socket and ring spanner so I really don't see a few thou' here or there being a problem?


40+ years of "spannering" and don't recall ever thinking "must throw that spanner away it's a sloppy fit"

[GC8]

Theyre all combis, but I had presumed that the open end would be easier to measure and compare.