nuts and bolts

[cadetchris]

how can you tell what type a nut of bolt is?

as in UNF or BSF

[taupe]

Hi

Measure the diameter and use a thread gauge is the best way.

Another way is to keep a labelled stock of known nuts and bolts and try them on the thread.

UNF bolts also usually have a circle on the head and circles on the nut flats.

[cadetchris]

now a thread gauge is a good idea, where can one get one?

[mike.perry]

From a good tool / hardware shop, they come in metric and imperial sizes.
Usual threads are BSF, BSW, UNF, UNC, Metric, Metric Fine

[Alec]

Hello Cadetchris,

a simple way is to measure across the flats. UNF\UNC will be fractional i.e 1\2", 9\16" etc metric will be 13, 15, 17 etc. Unfortunately some coincide e.g 1\4" UNF\UNC is also 11mm, but there are no common metric fasteners that a 11mm spanner fits. Whitworth fasteners are not simple fractions across flats as UNF\UNC, but the bolt diameters are. You can also measure the bolt diameter to determine if it is metric or imperial.

Thread gauges are usually simply threads per inch or metric equivalent so you will need something like a Zeus table to tell you the pitch of the thread for a specific fastener.

I hope that is not too confusing?

Alec