I do a lot of repair and custom work on electric lighting. This includes
retrofitting European lamps to American sockets and wiring.

Here in the states, the threading and sizes on our lamp piping is all based
on gas piping since our electric lamp industry evolved from our gas light
industry.

On the European lamps (mostly British and French) there is a thread I have
never been able to figure out.

It appears to be about 19tpi (or perhaps 1.33mm) and runs around .415 in.
outside dia (or perhaps 10.5mm).

It doesn't seem to match anything.

I made myself a tap several years ago, but it is wearing out and I would
love to find a real tap for it. Unfortunately I don't even know what size to
look for.

Any help would be greatly appreciated.

Paul K. Dickman

Paul K. Dickman wrote:

On the European lamps (mostly British and French) there is a thread I have
never been able to figure out.

Are you asking for the light bulb's thread? Or where "on the lamp" is
the thread you mean?


Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

From your details and the following link it might be the Holtzapfels
Threads thread (HOLTZ) listed
http://www.watchman.dsl.pipex.com/thread.html . From my experience much
of the UK lighting thread is BSB (British Standard Brass) but that is 26
TPI so not an option, the common new close replacement being M10 x 1. 19
TPI is used for BSP but at a slightly smaller diameter than you have
listed. From a quick google not much information on the Holtzapfels
Thread but its a start. IIRC some European thread are designated with a
G prefix but I can't think where, normally on pipe threads though.

Paul K. Dickman wrote:

I do a lot of repair and custom work on electric lighting. This includes
retrofitting European lamps to American sockets and wiring.

Here in the states, the threading and sizes on our lamp piping is all based
on gas piping since our electric lamp industry evolved from our gas light
industry.

On the European lamps (mostly British and French) there is a thread I have
never been able to figure out.

It appears to be about 19tpi (or perhaps 1.33mm) and runs around .415 in.
outside dia (or perhaps 10.5mm).

It doesn't seem to match anything.

I made myself a tap several years ago, but it is wearing out and I would
love to find a real tap for it. Unfortunately I don't even know what size to
look for.

Any help would be greatly appreciated.

Paul K. Dickman

"David Billington" wrote in message
...
From your details and the following link it might be the Holtzapfels
Threads thread (HOLTZ) listed
http://www.watchman.dsl.pipex.com/thread.html . From my experience much of
the UK lighting thread is BSB (British Standard Brass) but that is 26 TPI
so not an option, the common new close replacement being M10 x 1. 19 TPI
is used for BSP but at a slightly smaller diameter than you have listed.
From a quick google not much information on the Holtzapfels Thread but its
a start. IIRC some European thread are designated with a G prefix but I
can't think where, normally on pipe threads though.

Thanks. I run into the M10x1 pretty regularly. When I do, I do a little
dance of thankfulness.
I have probably into BSB but it is so close to our 27TPI thread and the
engagement is so short, I probably just threaded the socket on and didn't
notice.

The Holtzapfels thread shows as 19.9 TPI. This one falls exactly between the
18 and 20 pitch blades on my gauge, so I doubt that is it.

That is a great chart though.

I will try to google up something on the G prefix threads.

Thanks

Paul K. Dickman

No, it is the piping thread. The socket gets screwed onto it.

Paul K. Dickman

""Nick Müller"" wrote in message
...
Paul K. Dickman wrote:

On the European lamps (mostly British and French) there is a thread I
have
never been able to figure out.

Are you asking for the light bulb's thread? Or where "on the lamp" is
the thread you mean?


Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

Info here
http://www.webster-inst.com/techinfo...r/pipeconn.htm shows
G prefix means Gas thread and is I think the same as BSP.

A search for 19 TPI turned up this reference to 7/16 x 19
http://www.vintagecarparts.co.uk/en/...ipple-details/ .

These guys list a 7/16 x 19 http://www.uni-thread.com/tdcycle.html .
Search was 19 tpi thread, maybe that is close enough for your purpose.

Paul K. Dickman wrote:

"David Billington" wrote in message
k...

From your details and the following link it might be the Holtzapfels
Threads thread (HOLTZ) listed
http://www.watchman.dsl.pipex.com/thread.html . From my experience much of
the UK lighting thread is BSB (British Standard Brass) but that is 26 TPI
so not an option, the common new close replacement being M10 x 1. 19 TPI
is used for BSP but at a slightly smaller diameter than you have listed.
From a quick google not much information on the Holtzapfels Thread but its
a start. IIRC some European thread are designated with a G prefix but I
can't think where, normally on pipe threads though.


Thanks. I run into the M10x1 pretty regularly. When I do, I do a little
dance of thankfulness.
I have probably into BSB but it is so close to our 27TPI thread and the
engagement is so short, I probably just threaded the socket on and didn't
notice.

The Holtzapfels thread shows as 19.9 TPI. This one falls exactly between the
18 and 20 pitch blades on my gauge, so I doubt that is it.

That is a great chart though.

I will try to google up something on the G prefix threads.

Thanks

Paul K. Dickman

Paul K. Dickman wrote:

No, it is the piping thread. The socket gets screwed onto it.

Nothing metric.


Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

"David Billington" wrote in message
...
Info here
http://www.webster-inst.com/techinfo...r/pipeconn.htm shows G
prefix means Gas thread and is I think the same as BSP.

A search for 19 TPI turned up this reference to 7/16 x 19
http://www.vintagecarparts.co.uk/en/...ipple-details/ .

These guys list a 7/16 x 19 http://www.uni-thread.com/tdcycle.html .
Search was 19 tpi thread, maybe that is close enough for your purpose.

That 7/16-19 will probably work.

Still wish I knew what it's origins were.

Paul K. Dickman

Paul K. Dickman wrote:
I do a lot of repair and custom work on electric lighting. This includes
retrofitting European lamps to American sockets and wiring.

Here in the states, the threading and sizes on our lamp piping is all based
on gas piping since our electric lamp industry evolved from our gas light
industry.

On the European lamps (mostly British and French) there is a thread I have
never been able to figure out.

It appears to be about 19tpi (or perhaps 1.33mm) and runs around .415 in.
outside dia (or perhaps 10.5mm).

It doesn't seem to match anything.

I made myself a tap several years ago, but it is wearing out and I would
love to find a real tap for it. Unfortunately I don't even know what size to
look for.

Any help would be greatly appreciated.

Paul K. Dickman


go here
http://www.redapt.co.uk/index.htm

they have pdf's for download etc and products that may save you a lot
of work

Thanks to all who responded.

After seeing Dave Billington searching on "19 TPI" I did the same and found
a reference to it as an obsolete thread called "Copper pipe thread".

Thanks again

Paul K. Dickman

See below;

1.. Thread "Pas des becs" by Robert GIRARD )
Posted: Nov. 11, 2002 @ 14:22.
Hello I repair lamps in Provence, Luberon, France !!!! Could someone help
me to find the origin of threadings used in lamps, called in France "pas
français" : "Pas des Becs", or "Pas des becs de cuivre" = 10,85 mm diameter
and 1,33mm thread (19 thread/inch) ??? - and the others : "Pas de Paris"
(16,85mm diam.) and "Pas de Rouen" (!!!???!!!) ????? and the threads (may be
Withworth ? Empire ? or other ?) used to screwed ancient statuettes on their
marble base Thanks Best rgds RG

1.. On Nov. 11, 2002 @ 17:47, Alex Marrack ) wrote:
Thread names are often confusing, the first one you mention is the one
often used on French Gas burners and earlier French electric lamps. It is a
whitworth form thread, and is a 'non standard' size of English Pipe thread,
now standardised as British Standard Pipe thread, but dating back to about
1820 and maybe before.
The 19 TPI persists and is still used for 1/4" and 3/8" pies now (these
threads are bigger than the name implies and the 1/4 inch size pipe has an
OD of nearly half an inch (Dont ask!) The odd size thread was used over here
(UK) and called Copper pipe thread, not widely used for over 100 year.

Good work, you must have sifted through quite a lot. I always get a lot
of references to threads in computer programs clouding the search when
on the thread subject. Thats not to bad for me as I program for a living
but it doesn't help when looking for screw threads.

Many of the modern metric pipe threads are BSP in metric dimensions so
the reference 1 may very well be an obsolete english thread as mentioned
in 2. Searching for "copper pipe thread" turns up an awful lot to sift
through. What the next move?. If its that old and obsolete then you may
not have much luck finding info on the web. Whatever you find you may
have to resort to making another yourself unless the 7/16 x 19 is close
enough. I am not quite sure where I would start to look for a thread
that old and i'm in the UK, possibly send someone an email at the
science museum in London http://www.sciencemuseum.org.uk/ .

I'll mention it to a friend who has a thing about thread systems and see
where he would start.

Paul K. Dickman wrote:

Thanks to all who responded.

After seeing Dave Billington searching on "19 TPI" I did the same and found
a reference to it as an obsolete thread called "Copper pipe thread".

Thanks again

Paul K. Dickman

See below;

1.. Thread "Pas des becs" by Robert GIRARD )
Posted: Nov. 11, 2002 @ 14:22.
Hello I repair lamps in Provence, Luberon, France !!!! Could someone help
me to find the origin of threadings used in lamps, called in France "pas
français" : "Pas des Becs", or "Pas des becs de cuivre" = 10,85 mm diameter
and 1,33mm thread (19 thread/inch) ??? - and the others : "Pas de Paris"
(16,85mm diam.) and "Pas de Rouen" (!!!???!!!) ????? and the threads (may be
Withworth ? Empire ? or other ?) used to screwed ancient statuettes on their
marble base Thanks Best rgds RG

1.. On Nov. 11, 2002 @ 17:47, Alex Marrack ) wrote:
Thread names are often confusing, the first one you mention is the one
often used on French Gas burners and earlier French electric lamps. It is a
whitworth form thread, and is a 'non standard' size of English Pipe thread,
now standardised as British Standard Pipe thread, but dating back to about
1820 and maybe before.
The 19 TPI persists and is still used for 1/4" and 3/8" pies now (these
threads are bigger than the name implies and the 1/4 inch size pipe has an
OD of nearly half an inch (Dont ask!) The odd size thread was used over here
(UK) and called Copper pipe thread, not widely used for over 100 year.

"David Billington" wrote in message
...
Good work, you must have sifted through quite a lot. I always get a lot of
references to threads in computer programs clouding the search when on the
thread subject. Thats not to bad for me as I program for a living but it
doesn't help when looking for screw threads.

Many of the modern metric pipe threads are BSP in metric dimensions so the
reference 1 may very well be an obsolete english thread as mentioned in 2.
Searching for "copper pipe thread" turns up an awful lot to sift through.
What the next move?. If its that old and obsolete then you may not have
much luck finding info on the web. Whatever you find you may have to
resort to making another yourself unless the 7/16 x 19 is close enough. I
am not quite sure where I would start to look for a thread that old and
i'm in the UK, possibly send someone an email at the science museum in
London http://www.sciencemuseum.org.uk/ .

I'll mention it to a friend who has a thing about thread systems and see
where he would start.

That 7/16-19 tap will probably work fine. These threads just hold stuff
together. They don't need to seal anything.

Still, I would love to find the right thread in a spiral point machine tap.
Then I could just set up my tapping head and blast out all the sockets I
will ever need in a couple of hours.

Paul K. Dickman

I do a number of modifications to lamps for a friend here in the UK and
have not run across this thread, but saying that one will probably turn
up next week. Are these items which have been in the US for many years
or have they recently been imported. Do you have any idea of the
vintage. I presume a tap is required as you are modifying a ready made
part which would be a pain to set-up for thread cutting.

Paul K. Dickman wrote:

"David Billington" wrote in message
k...

Good work, you must have sifted through quite a lot. I always get a lot of
references to threads in computer programs clouding the search when on the
thread subject. Thats not to bad for me as I program for a living but it
doesn't help when looking for screw threads.

Many of the modern metric pipe threads are BSP in metric dimensions so the
reference 1 may very well be an obsolete english thread as mentioned in 2.
Searching for "copper pipe thread" turns up an awful lot to sift through.
What the next move?. If its that old and obsolete then you may not have
much luck finding info on the web. Whatever you find you may have to
resort to making another yourself unless the 7/16 x 19 is close enough. I
am not quite sure where I would start to look for a thread that old and
i'm in the UK, possibly send someone an email at the science museum in
London http://www.sciencemuseum.org.uk/ .

I'll mention it to a friend who has a thing about thread systems and see
where he would start.


That 7/16-19 tap will probably work fine. These threads just hold stuff
together. They don't need to seal anything.

Still, I would love to find the right thread in a spiral point machine tap.
Then I could just set up my tapping head and blast out all the sockets I
will ever need in a couple of hours.

Paul K. Dickman

"David Billington" wrote in message
...
I do a number of modifications to lamps for a friend here in the UK and
have not run across this thread, but saying that one will probably turn up
next week. Are these items which have been in the US for many years or have
they recently been imported. Do you have any idea of the vintage. I presume
a tap is required as you are modifying a ready made part which would be a
pain to set-up for thread cutting.


These are recently imported, but of antique or certainly vintage
manufacture. In retrospect, they may mostly have been French lamps, but
almost all the sockets of British manufacture.

They make an adapter for the bi-pin base bulbs to our American style screw
shell bulbs, but through bad design, it is conceivable that the customer
could reverse the adapter or change the plug and end up with the entire
metal exterior of the fixture attached to the hot side of the wiring. Even
in proper assembly it leaves the body attached to the neutral lead.

Needless to say, I refuse to use them.

The pipe is slightly larger in diameter than our standard 1/8"- 27 pipe. The
simplest and cleanest fix is to ream out one of our socket bases and
re-thread it to match.

Because of clearance and mounting issues, it is usually extremely difficult
to re-thread the piping.

Paul K. Dickman

I've just checked with my neighbour as he has a Machinery Publications
thread book first printed in London 1915, although his copy is about
1935. The only threads listed with 19 TPI are Whitworth based and it
gives the thread details for the Whitworth thread of that TPI which my
21st edition Machinery's still does. It does list 2 copper tube threads
both Whitworth thread form but unfortunately neither uses 19 TPI. One
was called the Manchester thread used by Manchester plumbers and was 16
TPI constant pitch, the other Copper tube thread was similar to BSP but
used a 20 TPI in the size range you refered to so close but not the one.
Both are now likely obsolete.

I spoke briefly to the guy I know that has a thing about threads and he
wondered about BSPP (British Standard Parallel Pipe) as he has run
across this in gearboxes for bearing retaining nuts, this thread
apparently being useful for various engineering applications not just
pipe threads. He did mention a company, unfortunately now defunct, that
listed 158 different threads it could supply tooling for right down to
the Budapest fire department thread. I think he said he had or knew
where one of their catalogues was so if possibly i'll try to get a look.
Is your email address at ameritech good, if I turn anything up i'll
email you there if the thread falls off the end of my news reader.

Can you email me a picture of the units, i'll run it by the light guy I
know and see what he says. He has some french contacts and experience
with french lighting. I'm on broadband so don't worry about the size too
much unless its absolutely huge 2mb/picture.

Do I like a challenge? yes. Delving into our industrial heritage, so
much of it, and this may be touching the early fringes regarding
standards, or may predate it. I just happen to know a few people that
like this stuff.

From a quick look Whitworth introduced his standardised threads in
about 1841 and apparently take-up was quick although the BSI (Britsh
Standards Institute) didn't come about until much later (early 1900s ?).
Knowing the vintage of the items you are working on would help to pin
down an industrial environment and may help identify the thread.

Cheers

DB

Paul K. Dickman wrote:

"David Billington" wrote in message
k...

I do a number of modifications to lamps for a friend here in the UK and
have not run across this thread, but saying that one will probably turn up
next week. Are these items which have been in the US for many years or have
they recently been imported. Do you have any idea of the vintage. I presume
a tap is required as you are modifying a ready made part which would be a
pain to set-up for thread cutting.


These are recently imported, but of antique or certainly vintage
manufacture. In retrospect, they may mostly have been French lamps, but
almost all the sockets of British manufacture.

They make an adapter for the bi-pin base bulbs to our American style screw
shell bulbs, but through bad design, it is conceivable that the customer
could reverse the adapter or change the plug and end up with the entire
metal exterior of the fixture attached to the hot side of the wiring. Even
in proper assembly it leaves the body attached to the neutral lead.

Needless to say, I refuse to use them.

The pipe is slightly larger in diameter than our standard 1/8"- 27 pipe. The
simplest and cleanest fix is to ream out one of our socket bases and
re-thread it to match.

Because of clearance and mounting issues, it is usually extremely difficult
to re-thread the piping.

Paul K. Dickman

On Sat, 7 Jan 2006 11:22:25 -0600, "Paul K. Dickman"
wrote:

They make an adapter for the bi-pin base bulbs to our American style screw
shell bulbs, but through bad design, it is conceivable that the customer
could reverse the adapter or change the plug and end up with the entire
metal exterior of the fixture attached to the hot side of the wiring. Even
in proper assembly it leaves the body attached to the neutral lead.

I hate Edison Screw lampholders. UK pattern BC fittings are much better.
Particularly for the SES pattern the self-unscrewing from thermal
cycling is a real annoyance.

Where we do have ES fittings, they're generally an improvement over the
simplest old style. It's not necessary to wire them so that the centre
is live ("hot") and the outside is neutral according to our rules, so
long as the lampholder used has an insulated outer body and the screw
contact is merely through a small metal finger at the side. This is
considered enough to enforce the "no touching the live wire"
requirement.

Andy Dingley wrote:

On Sat, 7 Jan 2006 11:22:25 -0600, "Paul K. Dickman"
wrote:

They make an adapter for the bi-pin base bulbs to our American style screw
shell bulbs, but through bad design, it is conceivable that the customer
could reverse the adapter or change the plug and end up with the entire
metal exterior of the fixture attached to the hot side of the wiring. Even
in proper assembly it leaves the body attached to the neutral lead.

I hate Edison Screw lampholders. UK pattern BC fittings are much better.
Particularly for the SES pattern the self-unscrewing from thermal
cycling is a real annoyance.

Where we do have ES fittings, they're generally an improvement over the
simplest old style. It's not necessary to wire them so that the centre
is live ("hot") and the outside is neutral according to our rules, so
long as the lampholder used has an insulated outer body and the screw
contact is merely through a small metal finger at the side. This is
considered enough to enforce the "no touching the live wire"
requirement.

Actually ES stands for Edison & Swan.
The Edison & Swan United Electric Light Co. was the company
they formed when they decided end the conflict over their
competing patents.

Tom

"Andy Dingley" wrote in message
...
On Sat, 7 Jan 2006 11:22:25 -0600, "Paul K. Dickman"
wrote:

They make an adapter for the bi-pin base bulbs to our American style screw
shell bulbs, but through bad design, it is conceivable that the customer
could reverse the adapter or change the plug and end up with the entire
metal exterior of the fixture attached to the hot side of the wiring. Even
in proper assembly it leaves the body attached to the neutral lead.

I hate Edison Screw lampholders. UK pattern BC fittings are much better.
Particularly for the SES pattern the self-unscrewing from thermal
cycling is a real annoyance.

Where we do have ES fittings, they're generally an improvement over the
simplest old style. It's not necessary to wire them so that the centre
is live ("hot") and the outside is neutral according to our rules, so
long as the lampholder used has an insulated outer body and the screw
contact is merely through a small metal finger at the side. This is
considered enough to enforce the "no touching the live wire"
requirement.

The Edisons are the same here. A paper shield protects the base from
accidental contact, so if it is wired to the hot side, the only conceivable
time someone could touch it is by sticking their finger in the empty socket,
or when the bulb is half unscrewed.

The problem is with the adapter. They use the same tube for the bayonet
connection as they do for the screw portion of the Edison side. Then they
jump one of the pins to it. If you accidentally reverse it in the bi-pin
socket, it connects the hot lead right to the shell.

Paul K. Dickman

On Sat, 7 Jan 2006 14:41:15 -0600, "Paul K. Dickman"
wrote:

or when the bulb is half unscrewed.

Not in the UK - that's the difference. As soon as you unscrew the bulb a
little, then the contact is broken and the exposed lamp base is no
longer live.