Lamp holder Base thread/pitch.

Thread Starter

MaxHeadRoom

Joined Jul 18, 2013
23,332
Search all over and can't seem to find if there is a standard thread for table lamp holders with the threaded base.
I don't have one on hand as yet, but I found that there is a variation out there of either 10mm or 1/8th NPT.
I would have thought it fairly standard, at least on each continent!
Anyone with knowledge on the size?
I just need to look out the required drill and tap combo.
Max.
 

Thread Starter

MaxHeadRoom

Joined Jul 18, 2013
23,332
Thanks, but it is not the E.S. (Edison Screw) that I am after, it is the table lamp ferrule mounting thread pitch & Dia..
Max.

upload_2018-11-16_14-43-50.jpeg
 
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drc_567

Joined Dec 29, 2008
1,134
There is a thread gage tool that has most of the common pitch sizes available on a knife-like fold-out assembly. U.S. thread sizes are produced, but there should also be a metric version. Simply match the teeth of the tool fold-out piece to the threaded item in question. Each of the tool fold-out pieces is stamped with a standard pitch size.
 

shortbus

Joined Sep 30, 2009
8,690
Thanks, but it is not the E.S. (Edison Screw) that I am after, it is the table lamp ferrule mounting thread pitch & Dia..
Max.
If you mean the threaded nipple in the photo, they are the same pitch as 1/8" pipe thread, they just don't have the sealing taper. https://www.engineeringtoolbox.com/american-standard-straight-pipe-threads-d_1520.html You almost have to either cut them in a lathe, buy the proper thread die. Most common pipe dies won't open up enough to cut straight pipe threads, since the proper thread diameter is somewhere near the middle of the taper of the NPT.

There used to be a company called Angelo Brothers, that sold that straight pipe in 36" lengths, but couldn't find a link to them in a quick Google.
 

Reloadron

Joined Jan 15, 2015
5,991
I come up with 3/8" (0.375 inch) 27 TPI using my thread pitch gauge and my calipers measuring the OD. This is part of a lamp I had laying around. I have the pitch gauges from working on guns and none of my metric gauges would mate with it so my guess is a US thread.

Ron
 

Thread Starter

MaxHeadRoom

Joined Jul 18, 2013
23,332
Thanks, I just found it also, I just wanted to confirm it (1/8th NPT) before the Tool supply closed today for a tap in case mine did not cover it.
Problem solved!:cool:
Max.
 

shortbus

Joined Sep 30, 2009
8,690
Thanks, I just found it also, I just wanted to confirm it (1/8th NPT) before the Tool supply closed today for a tap in case mine did not cover it.
Problem solved!:cool:
Max.
If your going to do a through hole with a NPT tap, just be aware it will be a lose thread. The NPT taper pipe is based on the fact 1/8" pipe is 0.405 OD. And the straight pipe is based at 3/8" like Ron said or about the middle of the NPT taper.

A few years ago I shortened a ceiling fixture for some one, the fixture was made in China, of course, and the tubes in it were a metric size so they are out there also.
 

Thread Starter

MaxHeadRoom

Joined Jul 18, 2013
23,332
Around here in NE Ohio I just go to my local Lowes or any home improvement store to buy just about any lamp parts I want. Here is an example of just about all parts. That includes brass or nickle what they call "lamp pipe".

Ron
The ones I have coming do not have any parts included, but after discovering it was NPT, I have since found that the short brass 1/8th NPT Close Nipple works fine for what I need to mount a series of lamp holders.
I had a 1/8th NPT tap on hand so I am good to go.
Thanks to all.
Max.

 
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