1/2" X 27 /28 tpi ?

[wyn]

I'm trying to find out the thread size on a bulb holder for a domestic lamp. The bit where the holder screws on to the lamp stand.

It's 1/2" inch diameter female thread and only about 5 - 10mm long so i'm finding it difficult to "read" the thread gauge.
It seems to come somewhere between 27 and 28 tpi, but i'm finding it difficult to pin it down exactly as the difference is so small.

The packet it came in said 1/2" BC. From what i can find out the BC refers to the bayonnet fitting.

The closest thread i can find is 1/2" British cycle thread (26 tpi). Or is that what the BC on the packet is refering to ?

Any ideas welcome.

Wyn.

 

[Robotstar5]

Try searching ES (edison screw), SES (small...) or MES (miniature...)

 

[Mikey D]

I think BC just stands for bayonet cap , is it a brass fitting you have bought ? the lampholder just screws onto the brass fitting ?

 

[Hitch]

You mean the underside of the lamp holder, not the actual e/s fitting?

Ive a die for them in the garage, ill have a look in a bit..

 

[wyn]

Thanks for the replies..

As you say Mikey i was thinking BC was beyonet cap as well.

It is the underside of a brass fitting that i'm interested in, i have made the rest of the lamp and need to connect a lamp holder to it by welding on a male threaded bit.

Hitch.... that would be spot on, i could get myself one then for future projects.


Here is a pic with the fitting upside down




And here's a pic of what it's going on

 

[Robotstar5]

DOH, should have read the post properly, thought you wanted the lamp thread! - are you going to market fancy reverse lights for Pajeros then?

 

[piman]

Hello Wyn,

I think you are correct and it is 1\2" cycle thread. It is a standard for lampholders and it doesn't matter what type of lamp fits the lampholder, screw, bayonet etc.

Alec

 

[wyn]

DOH, should have read the post properly, thought you wanted the lamp thread! - are you going to market fancy reverse lights for Pajeros then?

Yeah weld it onto the tow bar, the only trouble is it's 2.6m high.

 

[wyn]

Hello Wyn,

I think you are correct and it is 1\2" cycle thread. It is a standard for lampholders and it doesn't matter what type of lamp fits the lampholder, screw, bayonet etc.

Alec

Cheers piman...When i measured 1/2" and 27'ish tpi, Cycle thread was the only thing anywhere near.

 

[Hitch]

Okay, one i have is BSB, 1/2"x 26tpi.

Slightly different angle to cycle threads apparently

 

[wyn]

Thanks for having a look Hitch..i'll get hold of one of those.

I had a look at that site before but only got as far as the cycle thread.

Just had a quick look and Chronos do them for £15 .... Don't fancy cutting those threads on the lathe.

 

[chriskelland]

Ok, just a bit late, but if anyone has a strange or unusual thread have a look at the website for Tracy Tools. 1/2 X 26 is a standard size and will cost £8.00 for a tap (first, second or bottom) and £10.00 for a die.

www.tracytools.com

Just another satisfied customer.

Chris.

 

[wyn]

Cheers chris... i'll have a look at them as well.

 

[Hitch]

I was going to suggest Chronos, theyve got the die (carbon) for about £15 delivered

 

[aametalmaster]

http://www.antiquelampsupply.com/

 

[JOHN MANTOVA]

I'm trying to find out the thread size on a bulb holder for a domestic lamp. The bit where the holder screws on to the lamp stand.

It's 1/2" inch diameter female thread and only about 5 - 10mm long so i'm finding it difficult to "read" the thread gauge.
It seems to come somewhere between 27 and 28 tpi, but i'm finding it difficult to pin it down exactly as the difference is so small.

The packet it came in said 1/2" BC. From what i can find out the BC refers to the bayonnet fitting.

The closest thread i can find is 1/2" British cycle thread (26 tpi). Or is that what the BC on the packet is refering to ?

Any ideas welcome.

Wyn.

Buy one of the brass or steel male threads made to attach to the top of a standard lamp from any electrical spares shop. Then weld braze or solder as appropriate to your conduit. I know this is an old thread but it may help someone. The fitting is much cheaper

 

[Tiggy_dorset]

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