what thread ?

[fred]

A 13 mm spanner will fit the nut

An m8 nut will just about bite on the threads of the stud

The nut measures slightly larger across the flats, @ 13.10mm, than an M8 nu t ,@ 12.82mm

The internal diameter of the nut is 6.56mm, 0.259". using regular calipers

I realise its probably Imperial but thats as far as my knowledge will take me.

4 lengths of threaded rod were inserted into a brick wall to hold a metal b alcony. Only one had a nut on it. I had assumed the nuts would be metric b ut if it had been that easy the builder would have finished it I suppose. F inding imperial nuts and bolts in this neck of the woods is not going to be easy but if I knew exactly what I required it would be a great help.

[Rick Hughes]

If a builder has installed it, then almost certainly be ISO Metric, that is all that has been in Builders Merchants for decades.

You need to provide 3 measurements ...

# overall diam of the stud (OD) # number of teeth per inch, assuming you don't have a pitch gauge # if possible the root diam of the thread (smallest diam) .. through of the thread.

[fred]

nut ,@ 12.82mm

balcony. Only one had a nut on it. I had assumed the nuts would be metric but if it had been that easy the builder would have finished it I suppose. Finding 20 imperial nuts and bolts in this neck of the woods is not going to be easy but if I knew exactly what I required it would be a great help.

Stupid me. I never thought of checking the diameter of the stud.

The job was done over 23 years ago but I've rather short of round toits,

[Scott M]

If imperial: 13.1mm is 33/64 (.516") Nearest spanner size would .525" which is a 5/16" BSW or BSF (depending on pitch) which works out at

7.94mm outside diameter of the stud.

Or could it be M8 fine pitch (M8 x 1.0 instead of M8 x 1.25)?

Diameter of the stud and an thread pitch in TPI or mm would nail it (if you'll pardon the pun.)

[fred]

Argghhh. Not thinking straight. My usual method of checking nut and bolt sizes is to check them against another nut, or bolt,as the case might be. I n this case an M8 bolt would not fit the nut. After Ricks reply, I have a c heap tap and die set, I checked the stud. Thats funny Its 8mm thick x 1.25 thread.Tried an M8 nut on the existing clean stud. Bingo The other existin g studs that had never had a nut on them, after 20 odd years were gunged up with paint an rust. Ran an M8 die over them and now an M8 nut fits perfect ly.

Next time I'll engage brain first.

Thanks to all for the input

[Bob Minchin]

5/16 BSF is 22 tpi 5/16 BSW ia 18 tpi M8 x 1.25 is 20.32 tpi M8 x 1.0 is 25.4 tpi and often found on cars

if you extend the range of possibilities to US unified threads

then 5/16" threads can have most even number pitches from 18 to 48 tpi

[Scott M]

One place is the studs holding pressure plate to flywheel on LR Discoverys, M8x1.25 one end, M8x1 the other. I know this because, in footling under one that had a new clutch only a couple of years ago, of the 6 studs I found two sheared off and rattling about in the bellhousing. The other 4 were all showing signs of fatigue so had presumably been gorilla'd on with an air gun.

Gave me an excuse to buy a fine pitch M8 die :-)

[Rick Hughes]

should still be Metric ... most building sites steel has been metric since very early 80's

Round toits are always an issue.

[Rick Hughes]

No probs ... often just asking the question, helps you come up with teh answer.

[Rick Hughes]

This was a common fault on Series 2 LR's .... thought they would have fixed it by now

[Scott M]

What, from a company that, in the year 2000, was still producing vehicles with imperial fastners on it?! (Disco II prop shaft to handbrake drum)

[The Other Mike]

So not a UNC / UNF combination?

[Nthkentman]

A 13 mm spanner will fit the nut

An m8 nut will just about bite on the threads of the stud

The nut measures slightly larger across the flats, @ 13.10mm, than an M8 nut ,@ 12.82mm

The internal diameter of the nut is 6.56mm, 0.259". using regular calipers

I realise its probably Imperial but thats as far as my knowledge will take me.

4 lengths of threaded rod were inserted into a brick wall to hold a metal balcony. Only one had a nut on it. I had assumed the nuts would be metric but if it had been that easy the builder would have finished it I suppose. Finding imperial nuts and bolts in this neck of the woods is not going to be easy but if I knew exactly what I required it would be a great help.

5/16 bsf