I want to repair an old chair leg which is held on with a nut which is
missing. The neatest way will be to find a nut the right size. A M8
nut almost fits but binds after a turn or so, so I think it is likely to
be an imperial thread about the same size.

Can anyone tell from that what size imperial nut is likely to fit?

On 03/01/2014 11:58, BruceB wrote:
I want to repair an old chair leg which is held on with a nut which is
missing. The neatest way will be to find a nut the right size. A M8
nut almost fits but binds after a turn or so, so I think it is likely to
be an imperial thread about the same size.

Can anyone tell from that what size imperial nut is likely to fit?



M8 is 5/16", and depending on where it was made, it could be BSF, BSW,
UNC or UNF.

BSW and UNC share the same pitch (18 threads per inch at that size), but
have different shape threads, so are interchangeable as long as ultimate
strength is not an issue.

--
Tciao for Now!

John.

In article ,
says...

On 03/01/2014 11:58, BruceB wrote:
I want to repair an old chair leg which is held on with a nut which is
missing. The neatest way will be to find a nut the right size. A M8
nut almost fits but binds after a turn or so, so I think it is likely to
be an imperial thread about the same size.

Can anyone tell from that what size imperial nut is likely to fit?



M8 is 5/16", and depending on where it was made, it could be BSF, BSW,
UNC or UNF.

BSW and UNC share the same pitch (18 threads per inch at that size), but
have different shape threads, so are interchangeable as long as ultimate
strength is not an issue.

Thanks. It is old British furniture, coarse thread rather than fine (by
my eye) so I think I will get some 5/16 BSW nuts from ebay. I am
assuming they are described by their thread size rather than the AF
spanner size?

On 03/01/2014 12:16, BruceB wrote:
Thanks. It is old British furniture, coarse thread rather than fine (by
my eye) so I think I will get some 5/16 BSW nuts from ebay. I am
assuming they are described by their thread size rather than the AF
spanner size?

Correct. As confirmation, count the threads per inch on the stud, as it
is vaguely possible that if the chair is old enough (Centuries, not
decades), it may be a non-standard thread. If you're passing a car
spares shop, they should have 5/16" UNC nuts in stock, which will
probably be good enough.

--
Tciao for Now!

John.

On Fri, 03 Jan 2014 12:30:32 +0000, John Williamson wrote:

Correct. As confirmation, count the threads per inch on the stud, as it
is vaguely possible that if the chair is old enough (Centuries, not
decades), it may be a non-standard thread. If you're passing a car
spares shop, they should have 5/16" UNC nuts in stock, which will
probably be good enough.

This is one of the unseen bonuses of owning a lathe. You can simply make
one up to the exact specifications; handy because by no means all threads
are 60 degrees and some have different profiles of crests and roots. No
big deal perhaps for a sofa stud, but invaluable for classic cars/bikes
etc.

On 03/01/2014 11:58, BruceB wrote:
I want to repair an old chair leg which is held on with a nut which is
missing. The neatest way will be to find a nut the right size. A M8
nut almost fits but binds after a turn or so, so I think it is likely to
be an imperial thread about the same size.

Can anyone tell from that what size imperial nut is likely to fit?




Try a 3/8ths nut of whatever thread they might be

Bob H wrote:
On 03/01/2014 11:58, BruceB wrote:
I want to repair an old chair leg which is held on with a nut which is
missing. The neatest way will be to find a nut the right size. A M8
nut almost fits but binds after a turn or so, so I think it is likely to
be an imperial thread about the same size.

Can anyone tell from that what size imperial nut is likely to fit?




Try a 3/8ths nut of whatever thread they might be
Why? So it will be too big??

On 03/01/2014 16:31, Bob Minchin wrote:
Bob H wrote:
On 03/01/2014 11:58, BruceB wrote:
I want to repair an old chair leg which is held on with a nut which is
missing. The neatest way will be to find a nut the right size. A M8
nut almost fits but binds after a turn or so, so I think it is likely to
be an imperial thread about the same size.

Can anyone tell from that what size imperial nut is likely to fit?




Try a 3/8ths nut of whatever thread they might be
Why? So it will be too big??

It might be, I don't know.
The op said 8mm was too small, as it binds up. 3/8ths is the equivalent
of 9.52mm, so that's about 0.75mm bigger all round, and may well not
bind up on the threads.

Anyways, what do I know as I only had 40 years experience in engineering.

On 03/01/2014 18:28, Bob H wrote:
On 03/01/2014 16:31, Bob Minchin wrote:
Bob H wrote:
On 03/01/2014 11:58, BruceB wrote:
I want to repair an old chair leg which is held on with a nut which is
missing. The neatest way will be to find a nut the right size. A M8
nut almost fits but binds after a turn or so, so I think it is
likely to
be an imperial thread about the same size.

Can anyone tell from that what size imperial nut is likely to fit?




Try a 3/8ths nut of whatever thread they might be
Why? So it will be too big??

It might be, I don't know.
The op said 8mm was too small, as it binds up. 3/8ths is the equivalent
of 9.52mm, so that's about 0.75mm bigger all round, and may well not
bind up on the threads.

Anyways, what do I know as I only had 40 years experience in engineering.

From the OP's description of the problem, the size is more or less
correct, but the thread pitch is wrong. If the nut was too small, he
wouldn't even get it on to the end of the thread, unless it was a
tapered one, which is unlikely.

--
Tciao for Now!

John.

On Fri, 03 Jan 2014 18:28:46 +0000, Bob H wrote:

I want to repair an old chair leg which is held on with a nut which
is missing. The neatest way will be to find a nut the right size. A
M8 nut almost fits but binds after a turn or so, so I think it is
likely to be an imperial thread about the same size.

Can anyone tell from that what size imperial nut is likely to fit?

Try a 3/8ths nut of whatever thread they might be

Why? So it will be too big??

It might be, I don't know.
The op said 8mm was too small, as it binds up. 3/8ths is the equivalent
of 9.52mm, so that's about 0.75mm bigger all round, and may well not
bind up on the threads.

I'd hazard a guess that "binding up on the threads" is the last thing
it'll do.

I'll tell you for a fact that an M8 nut on an M7 thread will just happily
slide up and down without any threads getting even close to touching, let
alone "binding". I'd guess M9 (smaller, let's not forget than 3/8") on M8
would be very similar.

Anyways, what do I know as I only had 40 years experience in
engineering.

And you never came across the concept of "thread pitch" in that time?

On 03/01/2014 19:03, Adrian wrote:
On Fri, 03 Jan 2014 18:28:46 +0000, Bob H wrote:


Anyways, what do I know as I only had 40 years experience in
engineering.

And you never came across the concept of "thread pitch" in that time?

Maybe he's a chemical engineer? Tighten it up finger tight, and throw a
bucket of salty water over it to corrode it and stop it moving?

--
Tciao for Now!

John.

On Fri, 03 Jan 2014 18:28:46 +0000, Bob H wrote:

It might be, I don't know.
The op said 8mm was too small, as it binds up. 3/8ths is the equivalent
of 9.52mm, so that's about 0.75mm bigger all round, and may well not
bind up on the threads.

Anyways, what do I know as I only had 40 years experience in
engineering.

If the OP can get it on and run it up a few threads, then most likely
it's a TPI issue.

On Fri, 03 Jan 2014 11:58:32 +0000, BruceB wrote:

I want to repair an old chair leg which is held on with a nut which is
missing. The neatest way will be to find a nut the right size. A M8
nut almost fits but binds after a turn or so, so I think it is likely to
be an imperial thread about the same size.

Can anyone tell from that what size imperial nut is likely to fit?

Type Size Dia Inch TPI Dia mm Pitch mm

BA 0 0.2362 25.38 6.00 1.00
MF 6 0.236 33.87 6 0.75
M 6 0.236 25.40 6 1
UNEF 1/4 0.25 32 6.35 0.79
UNF 1/4 0.25 28 6.35 0.91
BSF 1/4 0.25 26 6.35 0.98
BSW 1/4 0.25 20 6.35 1.27
UNC 1/4 0.25 20 6.35 1.27
MF 7 0.276 33.87 7 0.75
M 7 0.276 25.40 7 1
BSF 9/32 0.2812 26 7.14 0.98
UNEF 5/16 0.3125 32 7.94 0.79
UNF 5/16 0.3125 24 7.94 1.06
BSF 5/16 0.3125 22 7.94 1.15
BSW 5/16 0.3125 18 7.94 1.41
UNC 5/16 0.3125 18 7.94 1.41
MF 8 0.315 25.40 8 1
M 8 0.315 20.32 8 1.25
M 9 0.354 20.32 9 1.25
UNEF 3/8 0.375 32 9.53 0.79
UNF 3/8 0.375 24 9.53 1.06
BSF 3/8 0.375 20 9.53 1.27
BSW 3/8 0.375 16 9.53 1.59
UNC 3/8 0.375 16 9.53 1.59
MF 10 0.394 33.87 10 0.75
M 10 0.394 16.93 10 1.5

I once worked at a company that had a Standards Room. One of the guys was a
real expert on Screw Thread Gauges (which we used to make) and was
consulted by the National Physical Laboratory on many occassions. I gleaned
quite a lot about the finer points of threads. There is a lot to them when
you get into precision matters - especially when you get into wear
allowances on gauges.


--

DerbyBorn

"MattyF" wrote in message
...
On Fri, 03 Jan 2014 11:58:32 +0000, BruceB wrote:

I want to repair an old chair leg which is held on with a nut which is
missing. The neatest way will be to find a nut the right size. A M8
nut almost fits but binds after a turn or so, so I think it is likely to
be an imperial thread about the same size.

Can anyone tell from that what size imperial nut is likely to fit?

Type Size Dia Inch TPI Dia mm Pitch mm

BA 0 0.2362 25.38 6.00 1.00
MF 6 0.236 33.87 6 0.75
M 6 0.236 25.40 6 1
UNEF 1/4 0.25 32 6.35 0.79
UNF 1/4 0.25 28 6.35 0.91
BSF 1/4 0.25 26 6.35 0.98
BSW 1/4 0.25 20 6.35 1.27
UNC 1/4 0.25 20 6.35 1.27
MF 7 0.276 33.87 7 0.75
M 7 0.276 25.40 7 1
BSF 9/32 0.2812 26 7.14 0.98
UNEF 5/16 0.3125 32 7.94 0.79
UNF 5/16 0.3125 24 7.94 1.06
BSF 5/16 0.3125 22 7.94 1.15
BSW 5/16 0.3125 18 7.94 1.41
UNC 5/16 0.3125 18 7.94 1.41
MF 8 0.315 25.40 8 1
M 8 0.315 20.32 8 1.25
M 9 0.354 20.32 9 1.25
UNEF 3/8 0.375 32 9.53 0.79
UNF 3/8 0.375 24 9.53 1.06
BSF 3/8 0.375 20 9.53 1.27
BSW 3/8 0.375 16 9.53 1.59
UNC 3/8 0.375 16 9.53 1.59
MF 10 0.394 33.87 10 0.75
M 10 0.394 16.93 10 1.5


Thanks! Something I'd been looking for!
But what are those H and HF threads ?
Never heard of them before.

Jim Hawkins

On Mon, 06 Jan 2014 05:32:00 +0000, Jim Hawkins wrote:

"MattyF" wrote in message
...
On Fri, 03 Jan 2014 11:58:32 +0000, BruceB wrote:

I want to repair an old chair leg which is held on with a nut which is
missing. The neatest way will be to find a nut the right size. A M8
nut almost fits but binds after a turn or so, so I think it is likely
to be an imperial thread about the same size.

Can anyone tell from that what size imperial nut is likely to fit?

Type Size Dia Inch TPI Dia mm Pitch mm

BA 0 0.2362 25.38 6.00 1.00 MF 6 0.236 33.87 6 0.75 M 6 0.236 25.40 6 1
UNEF 1/4 0.25 32 6.35 0.79 UNF 1/4 0.25 28 6.35 0.91 BSF 1/4 0.25 26
6.35 0.98 BSW 1/4 0.25 20 6.35 1.27 UNC 1/4 0.25 20 6.35 1.27 MF 7
0.276 33.87 7 0.75 M 7 0.276 25.40 7 1 BSF 9/32 0.2812 26 7.14 0.98
UNEF 5/16 0.3125 32 7.94 0.79 UNF 5/16 0.3125 24 7.94 1.06 BSF 5/16
0.3125 22 7.94 1.15 BSW 5/16 0.3125 18 7.94 1.41 UNC 5/16 0.3125 18
7.94 1.41 MF 8 0.315 25.40 8 1 M 8 0.315 20.32 8 1.25 M 9 0.354 20.32
9 1.25 UNEF 3/8 0.375 32 9.53 0.79 UNF 3/8 0.375 24 9.53 1.06 BSF 3/8
0.375 20 9.53 1.27 BSW 3/8 0.375 16 9.53 1.59 UNC 3/8 0.375 16 9.53
1.59 MF 10 0.394 33.87 10 0.75 M 10 0.394 16.93 10 1.5


Thanks! Something I'd been looking for!
But what are those H and HF threads ?
Never heard of them before.

Jim Hawkins

Do you mean M and MF? That would be Metric and Metric Fine.
I look after a huge selection of nuts and bolts for antique machinery,
and get given thousands of nuts and bolts that have to be identified and
stored. Since nobody on the Net seems to have done it, I collected data
about lots of thread types and sorted them in ascending order of
diameter. I have a table for 1/16 BSW to 6 inch BSW. Perhaps it could be
hosted somewhere.

"MattyF" wrote in message
...
On Mon, 06 Jan 2014 05:32:00 +0000, Jim Hawkins wrote:

"MattyF" wrote in message
...
On Fri, 03 Jan 2014 11:58:32 +0000, BruceB wrote:

I want to repair an old chair leg which is held on with a nut which is
missing. The neatest way will be to find a nut the right size. A M8
nut almost fits but binds after a turn or so, so I think it is likely
to be an imperial thread about the same size.

Can anyone tell from that what size imperial nut is likely to fit?

Type Size Dia Inch TPI Dia mm Pitch mm

BA 0 0.2362 25.38 6.00 1.00 MF 6 0.236 33.87 6 0.75 M 6 0.236 25.40 6 1
UNEF 1/4 0.25 32 6.35 0.79 UNF 1/4 0.25 28 6.35 0.91 BSF 1/4 0.25 26
6.35 0.98 BSW 1/4 0.25 20 6.35 1.27 UNC 1/4 0.25 20 6.35 1.27 MF 7
0.276 33.87 7 0.75 M 7 0.276 25.40 7 1 BSF 9/32 0.2812 26 7.14 0.98
UNEF 5/16 0.3125 32 7.94 0.79 UNF 5/16 0.3125 24 7.94 1.06 BSF 5/16
0.3125 22 7.94 1.15 BSW 5/16 0.3125 18 7.94 1.41 UNC 5/16 0.3125 18
7.94 1.41 MF 8 0.315 25.40 8 1 M 8 0.315 20.32 8 1.25 M 9 0.354 20.32
9 1.25 UNEF 3/8 0.375 32 9.53 0.79 UNF 3/8 0.375 24 9.53 1.06 BSF 3/8
0.375 20 9.53 1.27 BSW 3/8 0.375 16 9.53 1.59 UNC 3/8 0.375 16 9.53
1.59 MF 10 0.394 33.87 10 0.75 M 10 0.394 16.93 10 1.5


Thanks! Something I'd been looking for!
But what are those H and HF threads ?
Never heard of them before.

Jim Hawkins

Do you mean M and MF? That would be Metric and Metric Fine.

Yes ! Should have put the glasses on!

I look after a huge selection of nuts and bolts for antique machinery,
and get given thousands of nuts and bolts that have to be identified and
stored. Since nobody on the Net seems to have done it, I collected data
about lots of thread types and sorted them in ascending order of
diameter. I have a table for 1/16 BSW to 6 inch BSW. Perhaps it could be
hosted somewhere.

Jim Hawkins

Thanks, I learned a bit about threads from this thread.

A 5/16 UNC was the correct TPI and solved the problem as an interference
fit.