Cant find the correct screw to hold up my pendants

[Kevstir]

Hi Guys

Having a bit of a problem tracking down some replacement screws for some ceiling pendants, the house is a 1930's build with medal conduit pipes , the screw in the picture is the only one I have , a previous owner decided to hold the pendants up with wood screws lol, she has went and bought some new fancy light shades that are a tad heavy so want to fix the pendants properly with the correct screws, tried everywhere local and all they keep saying is that it’s an imperial thread and i will be lucky to track them down.

I’m pretty sure you electricians will have come across this before, so hoping someone might be able to help, iv compared threads with metric screws, the thread matches an m6 screw but the diameter of the m6 is to big, to me it looks like an m5 diameter screw with an m6 thread..


My mate suggested tapping the holes up to m6 but tbh I scant be arsed with the hassle lol

whats this screw

• Kevstir
• 16 Apr 2011
• 1

Kev

 

[plugwash]

I'll bet it's some imperial size. The problem is there are so bloody many systems.

Could be a 7/32 BSF thread but without getting a proper set of thread gauges on the thread and a set of calipers on the diameter it's hard to tell.

 

[JohnW2]

Could be a 7/32 BSF thread but without getting a proper set of thread gauges on the thread and a set of calipers on the diameter it's hard to tell.

Indeed - and what about 0 BA, which I think is pretty close to 7/32" BSF. BA screws were pretty common in anything electrical.

Kind Regards, John.

 

[plugwash]

0BA seemed too fat to me if his discription of the diameter is anything like accurate. Still worth a try though.

As I said without a set of calipers and thread gauges to measure the screw it's very hard to tell.

 

[Lectrician]

I would say it would be a 2BA thread, they are very common with older electrical items.

And thats the key here - older electrics. Are these conduit boxes in place with the existing wiring? The money spent on these fancy lights may be better spent by putting it towards a rewire!

Any chance of some pics?

Have a look around this site...
http://www.wdsltd.co.uk/products/St...21-Countersunk-Socket-Screws-Imperial-BA-894/

 

[Adam_151]

Its 2BA for imperial BESA boxes, I was told an M5 will just about fit, but it'll be tight as its slightly larger diameter and the head won't sit square as the thread angle is different

Think you can still buy 2BA machine screws on ebay though, as people still need them for older cars etc

You'll probably find the conduit is the earth so if fitting fancy fittings, make sure you soundly lug a bit of 1.5mm single earth onto the hole in the back of the box. Also consider having a perioidic inspection done, the conduit does tend to go high resistance across the joints over the years

 

[wingcoax]

The problem being that the screws are normally brass and break off over the years. I have done a good few replacement lights over the last three years and all the screws were 2ba, i am able to scource from a local tool shack(NOT B&Q) so a good merchants should be able to help.

 

[TicklyT]

A traditional ironmonger may have BA screws in stock, usually the even number sizes, as will many screw and fastener specialists.

I have seen what are labelled as 2, 4 and 6BA screws hanging up in little plastic bags in Wilkinsons stores, but they also have 6mm pan head screws labelled as 1/4"BSW, so I have my doubts....

BA sizes are still popular with model builders, so model shops may have some.

http://www.chronos.ltd.uk/acatalog/Steel_BA_Countersunk_Head_Screws.html may be able to help.

If all else fails, get yourself an appropriate sized thread tap, probably 4 or 5mm. Just a taper tap will do the job. Re-thread the holes to take more common metric screws - much nicer than trying to mash a metric screw into the wrong size thread, shearing it off in the process, and leaving an unusable lug.
http://www.chronos.ltd.uk/acatalog/M5x0-8-Carbon-taps.html

 

[londonboy]

Send me a PM and I'll send you some, I've got loads of 2BA's.

 

[MrTinker]

and what about 0 BA, which I think is pretty close to 7/32" BSF. BA screws were pretty common in anything electrical.

If it was 0 BA a M6 bolt would go in, as 0 BA has a major diameter of 5.99948mm and a pitch of 1.00076mm, although the form angle is different, it will fit no problem.

It could be 7/32 BSF however the pitch of the threads is closer to M5 than M6

If the pitch of the threads is close to M6 but a smaller diameter I would say it's 7/32 Whitworth(BSW).

BSW & BSF machine screws are readily available, try eBay or a local engineering supplier

 

[foxhole]

Loop a thin wire thru the holes and use wood screw or self tapper.

 

[holmslaw]

..

 

[ricicle]

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=4829029

Edited for the correct product.

 

[holmslaw]

..

 

[ricicle]

Ooops - cheers Holmy I have now corrected the link.