I bought an old lamp and rewired it. Not sure of the age or origin, but it looks Art Deco. Here are some pictures:
https://www.flickr.com/photos/138493...7650682178678/

I had to remove the screws to rewire the lamp. Some of the screws were hard to remove and the slots got damaged. Now I'd like to replace the screws, but they're a really weird size. Here are the details:

- Brass screw, slotted round head
- Length: 8 mm
- Diameter: 3.70 mm
- Pitch 0.78 mm (as best as I can measure)

Here's what they aren't (because I've tried and they don't fit):

- #6-32 UNC
- #8-32 UNC
- 5/32" British Standard Whitworth
- 4 BA
- M4

For now, I've reassembled the lamp with the original screws. However, it bugs me that I can't identify the originals. Am I missing an obvious size?

Best wishes,

Chris

On 02/28/2015 3:31 PM, Christopher Tidy wrote:
....

Here's what they aren't (because I've tried and they don't fit):

- #6-32 UNC
- #8-32 UNC
....

I notice you've listed no numbered UNF in the above...that'd be my
firstest guess sight unseen...

--

Am Samstag, 28. Februar 2015 22:36:46 UTC+1 schrieb dpb:
On 02/28/2015 3:31 PM, Christopher Tidy wrote:
...

Here's what they aren't (because I've tried and they don't fit):

- #6-32 UNC
- #8-32 UNC
...

I notice you've listed no numbered UNF in the above...that'd be my
firstest guess sight unseen...

All the UNF pitches looked too fine. These are pretty coarse screws.

Christopher Tidy wrote:

I bought an old lamp and rewired it. Not sure of the age or origin, but it
looks Art Deco. Here are some pictures:
https://www.flickr.com/photos/138493...7650682178678/

I had to remove the screws to rewire the lamp. Some of the screws were
hard to remove and the slots got damaged. Now I'd like to replace the
screws, but they're a really weird size. Here are the details:

- Brass screw, slotted round head
- Length: 8 mm
- Diameter: 3.70 mm
- Pitch 0.78 mm (as best as I can measure)

Here's what they aren't (because I've tried and they don't fit):

- #6-32 UNC
- #8-32 UNC
- 5/32" British Standard Whitworth
- 4 BA
- M4
There are some "deprecated" UN threads that haven't peen seen in ages.
A couple I know off the top of my head are 6-48 and 12-32.

The 6-48 is common on guitars.

Jon

Jon Elson wrote:
Christopher Tidy wrote:

I bought an old lamp and rewired it. Not sure of the age or origin,
but it looks Art Deco. Here are some pictures:
https://www.flickr.com/photos/138493...7650682178678/

I had to remove the screws to rewire the lamp. Some of the screws
were hard to remove and the slots got damaged. Now I'd like to
replace the screws, but they're a really weird size. Here are the
details:

- Brass screw, slotted round head
- Length: 8 mm
- Diameter: 3.70 mm
- Pitch 0.78 mm (as best as I can measure)

Here's what they aren't (because I've tried and they don't fit):

- #6-32 UNC
- #8-32 UNC
- 5/32" British Standard Whitworth
- 4 BA
- M4
There are some "deprecated" UN threads that haven't peen seen in ages.
A couple I know off the top of my head are 6-48 and 12-32.

The 6-48 is common on guitars.

Jon

Common on scope mounts too .

--
Snag

On Saturday, February 28, 2015 at 4:31:28 PM UTC-5, Christopher Tidy wrote:
I bought an old lamp and rewired it. Not sure of the age or origin, but it looks Art Deco. Here are some pictures:
https://www.flickr.com/photos/138493...7650682178678/

I had to remove the screws to rewire the lamp. Some of the screws were hard to remove and the slots got damaged. Now I'd like to replace the screws, but they're a really weird size. Here are the details:

- Brass screw, slotted round head
- Length: 8 mm
- Diameter: 3.70 mm
- Pitch 0.78 mm (as best as I can measure)

Here's what they aren't (because I've tried and they don't fit):

- #6-32 UNC
- #8-32 UNC
- 5/32" British Standard Whitworth
- 4 BA
- M4

For now, I've reassembled the lamp with the original screws. However, it bugs me that I can't identify the originals. Am I missing an obvious size?

Best wishes,

Chris

Looking on the internet at screw threads, it looks like 6-32 is a little small and 8-32 a bit large. But the pitch is real close.

http://en.wikipedia.org/wiki/Unified_Thread_Standard This site has screw dimensions in both inch and metric.

Dan

On 2015-02-28, dpb wrote:
On 02/28/2015 3:31 PM, Christopher Tidy wrote:
...

Here's what they aren't (because I've tried and they don't fit):

- #6-32 UNC
- #8-32 UNC
...

I notice you've listed no numbered UNF in the above...that'd be my
firstest guess sight unseen...

Well ... first off -- the pitch he measured is within 1.7 % of a
32 TPI thread, and given the stated uncertainty of that pitch
measurement, it quite likely *is* 32 TPI.

However, the diameter is a bit large. 6-32 should be a 0.138"
clearance hole, and what he has is a bit fatter than that. But I'm not
sure about the diameter being any particular standard number size. Some
manufacturers in the US were using non-standard proprietary threads just
to keep a captive market.

Any clue as to where the lamp came from? Given the wide range
screws that he tried, I suspect that the lamp is currently in the UK. :-)

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 1/03/2015 7:01 AM, Christopher Tidy wrote:
I bought an old lamp and rewired it. Not sure of the age or origin, but it looks Art Deco. Here are some pictures:
https://www.flickr.com/photos/138493...7650682178678/

I had to remove the screws to rewire the lamp. Some of the screws were hard to remove and the slots got damaged. Now I'd like to replace the screws, but they're a really weird size. Here are the details:

- Brass screw, slotted round head
- Length: 8 mm
- Diameter: 3.70 mm
- Pitch 0.78 mm (as best as I can measure)

Here's what they aren't (because I've tried and they don't fit):

- #6-32 UNC
- #8-32 UNC
- 5/32" British Standard Whitworth
- 4 BA
- M4

For now, I've reassembled the lamp with the original screws. However, it bugs me that I can't identify the originals. Am I missing an obvious size?

Best wishes,

Chris



Have you explored the BA thread charts (British Association ) commonly
used on electrical equipment in the wayback days.

On Sat, 28 Feb 2015 13:31:26 -0800 (PST), Christopher Tidy
wrote:

I bought an old lamp and rewired it. Not sure of the age or origin, but it looks Art Deco. Here are some pictures:
https://www.flickr.com/photos/138493...7650682178678/

I had to remove the screws to rewire the lamp. Some of the screws were hard to remove and the slots got damaged. Now I'd like to replace the screws, but they're a really weird size. Here are the details:

- Brass screw, slotted round head
- Length: 8 mm
- Diameter: 3.70 mm
- Pitch 0.78 mm (as best as I can measure)

Here's what they aren't (because I've tried and they don't fit):

- #6-32 UNC
- #8-32 UNC
- 5/32" British Standard Whitworth
- 4 BA
- M4

For now, I've reassembled the lamp with the original screws. However, it bugs me that I can't identify the originals. Am I missing an obvious size?

Best wishes,

Chris

The standard for M4-0.7 is very close at Max Dia - 3.978 and Min dia -
3.838, pitch is 0.7mm.

It could be simply non-precise manufacturing as I've noticed that say
6-32 screws out of electrical appliances often seem slightly smaller
then standard.
--
Cheers,

John B.

On Sat, 28 Feb 2015 13:31:26 -0800, Christopher Tidy wrote:
I bought an old lamp and rewired it. [snip]
I had to remove the screws to rewire the lamp. Some of the screws were hard to remove and the slots got damaged. Now I'd like to replace the screws, but they're a really weird size. Here are the details:

- Brass screw, slotted round head
- Length: 8 mm
- Diameter: 3.70 mm
- Pitch 0.78 mm (as best as I can measure)

I encountered some screws about that size while rewiring some 40-year-old
light fixtures; 9 mm length, 4.0 mm diam, apparently 32 tpi (0.794 mm).

The screws used in wire cabinet pulls (U-shaped metal handles, see URL
http://www.houzz.com/photos/cabinet-and-drawer-handle-pulls/wire-cabinet-pull
) sometimes are close to the desired diameter. Eg, all the screws in
several batches I've got are 3.79 mm (about 0.148") diameter with 32 tpi.
#8-32 screws are too large to fit these handles, but the 4 mm screws from
the old light fixtures fit them.

Here's what they aren't (because I've tried and they don't fit):
- #6-32 UNC
- #8-32 UNC
- 5/32" British Standard Whitworth
- 4 BA
- M4
....
--
jiw

Am Sonntag, 1. März 2015 03:30:47 UTC+1 schrieb DoN. Nichols:

Any clue as to where the lamp came from? Given the wide range
screws that he tried, I suspect that the lamp is currently in the UK. :-)

It's currently in Germany. I bought it from a guy here, but know nothing more about its origin. The lampholders use an Edison screw (E27).

I did wonder if the thread was M4 x 0.8 mm. Apparently this thread exists, but is extremely rare. But I haven't been able to find an M4 x 0.8 mm screw to try out the theory.

Chris

On 3/1/2015 6:43 AM, Christopher Tidy wrote:
....
I did wonder if the thread was M4 x 0.8 mm. Apparently this thread exists, but is extremely rare. But I haven't been able to find an M4 x 0.8 mm screw to try out the theory.

Chris


You could turn a short length of M4 x .8 to test. .8 should be a pitch
available on your lathe - it's the standard/coarse M5 pitch.

Bob

On Sun, 1 Mar 2015 03:43:05 -0800 (PST), Christopher Tidy
wrote:

Am Sonntag, 1. März 2015 03:30:47 UTC+1 schrieb DoN. Nichols:

Any clue as to where the lamp came from? Given the wide range
screws that he tried, I suspect that the lamp is currently in the UK. :-)

It's currently in Germany. I bought it from a guy here, but know nothing more about its origin. The lampholders use an Edison screw (E27).

I did wonder if the thread was M4 x 0.8 mm. Apparently this thread exists, but is extremely rare. But I haven't been able to find an M4 x 0.8 mm screw to try out the theory.

Got a lathe and the proper gearing? Make one to try!

--
Now therefore, be it Resolved by the Fiftieth Annual Convention
of the Veterans of Foreign Wars of the United States, That we
hereby declare that we are unalterably opposed to any program
which would entail the surrender of any part of the sovereignty
of the United States of America in favor of a world government.

--Veterans of Foreign Wars

Am Sonntag, 1. März 2015 17:57:49 UTC+1 schrieb Larry Jaques:

Got a lathe and the proper gearing? Make one to try!

In England, yes. Here, sadly not.

Chris

An accquaintance of mine does old lamps. He say 8-40 is a standard on
those. 32 and 40 tpi were standards not much used today.

CP

MOP CAP fired this volley in news:2015030110215814330-
email@domaincom:

32 and 40 tpi were standards not much used today.


8-32 not much used? Really?
Lloyd

On Sun, 1 Mar 2015 09:35:27 -0800 (PST), Christopher Tidy
wrote:

Am Sonntag, 1. März 2015 17:57:49 UTC+1 schrieb Larry Jaques:

Got a lathe and the proper gearing? Make one to try!

In England, yes. Here, sadly not.

Get longer arms!

--
Now therefore, be it Resolved by the Fiftieth Annual Convention
of the Veterans of Foreign Wars of the United States, That we
hereby declare that we are unalterably opposed to any program
which would entail the surrender of any part of the sovereignty
of the United States of America in favor of a world government.

--Veterans of Foreign Wars