Thread identification help please.

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DrPhill

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We have an old hand-made chest of drawers. One of the nuts holding a handle on has disappeared. I need to identify the thread in order to replace it.

The fitting has a threaded bar which goes from the outside to the inside of the drawer front. I have measured the thread of the bar (male thread). I get diameter 4mm (high confidence), and five threads to four mm (medium confidence) so pitch is 0.8mm.

Is there a site where I can look up the official size/name?

All help gratefully received.
 
Could be M4 coarse (that's 0.7mm pitch). M4 fine is 0.5mm pitch. But if it's old and British (or US) then it'll probably be a UN or BSW thread.

EDIT: An 8-32 UNC thread has 32 TPI (0.794mm pitch) and an external diameter very close to 4mm, so it could be that too. 5/32" BSW is the same (albeit a very slightly different thread form). Try getting some M4 coarse nuts, and if it's tight then either an 8-32 UNC or 5/32" BSW nut should work.
 
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Assuming it's British made, the thread will be 5/32" BSW, which was used for drawer handles (I still have some). It's the same thread as originally used for Meccano, so if you still have some of that lying around you can swipe one of the nuts. There were never enough Meccano nuts anyway, so one less won't notice. The pitch of 5/32" BSW is 32 tpi which converts to 0.8 mm, so if you force an M4 x 0.7 mm nut on to it you will graunch the thread.

By the way, some drawer handles used 1/8" BSW. I have some of those too.

Les
 
Thanks for that both of you.
The chest of drawers was British made. Probably 20 to 30 years ago. I’m going to guess it’s an imperial (non metric) thread. So I will order some 5/32 BSW.
But I won’t force it……
 
For the sake of accuracy, the British Standard BS84-1956 which covers BSW & BSF threads does not list 5/32 in either series. In fact there are no '32nds' listed in BSW but, oddly, 7/32 & 9/32 are listed in BSF though they are non-prefered and (to be honest) add little to this discussion.

There ARE 3rd party thread tables which do list 5, 7 & 9 /32 diameters but not BS84.

I would be a little surprised - though not incredulous - to find something made even 30 years ago - in the UK - to have anything other than Metric threads - - - though I am not familiar with the intricacies of cabinet fittings, so there may well be some 'historic' reason that Whitworth threads were/are still in use in that field.
 
I would be a little surprised - though not incredulous - to find something made even 30 years ago - in the UK - to have anything other than Metric threads - - - though I am not familiar with the intricacies of cabinet fittings, so there may well be some 'historic' reason that Whitworth threads were/are still in use in that field.

I was just thinking exactly the same thing as J-G......Highly unlikely to be an imperial thread if the chest is only 20 or 30 years old!
Unless the handles are off an older cabinet and repurposed on this chest of drawers?
 
Thanks everyone who has commented. I am still not sure what nuts I need, but it seems the most useful and cost effective approach is to get a small set of m4/5/6/8 from the global tat-bazaar. Even if the nut I want is not m4 the rest are most likely to be useful. If I buy imperial and require metric then I have some useless nuts.

I checked with my wife (who knows more of the provenance of the piece) and it was hand made maybe thirty years ago by a retired carpenter. I could argue for or against imperial sizes based on this information. He might have had left-over stock to use up, or he might have had enough turnover to have run out of old stock.
 
Thanks everyone who has commented. I am still not sure what nuts I need, but it seems the most useful and cost effective approach is to get a small set of m4/5/6/8 from the global tat-bazaar. Even if the nut I want is not m4 the rest are most likely to be useful. If I buy imperial and require metric then I have some useless nuts.

I checked with my wife (who knows more of the provenance of the piece) and it was hand made maybe thirty years ago by a retired carpenter. I could argue for or against imperial sizes based on this information. He might have had left-over stock to use up, or he might have had enough turnover to have run out of old stock.
OK, so its not M4 coarse..... :(
What do you reckon I should try next........ 5/32 BSW?
 
Not really a serious suggestion but it would work. Use a square of Oak with a hole in it that matches the bolt under the threads. If you wanted uniformity you could do it to them all.
I’m presuming you have tried removing another nut or the handle and taking it to a good hardware shop?
Ian
 
Not really a serious suggestion but it would work. Use a square of Oak with a hole in it that matches the bolt under the threads. If you wanted uniformity you could do it to them all.
I’m presuming you have tried removing another nut or the handle and taking it to a good hardware shop?
Ian
Not a bad idea Ian. I have some hardwood scraps. That will give me something to do during the speech tomorrow.
as for ’a good hardware shop’ - I am not sure where I would find one of those. The last time I was in a good hardware shop was fifteen years or so ago in Ross on Wye. I now live in south Devon.
 
Possibly even BA screws - 3BA is close.

When tracking down replacement tuner screws for an old British made banjo I eventually found they were 6BA - I have metric, UNF and BSF similar sizes as a by-product.

Ebay vendors seem to have 6 or 10 packs of every possibility for a pound or two each.
 
As has been mentioned 5/32 BSW was very common for handles of all sorts going back way before the 1956 BS was published and were commonly still used into the 1960s.
As for not enough Meccano nuts, I don’t seem to have a problem…..
IMG_9693.jpeg
 
It's such a "joy" trying to work out Imperial threads. I rebuilt a couple of old Startrite saws a few years ago and there was a wonderful mix of metric, BSW, BSF, and BA hardware, and the main spindle (if I recall correctly) has Imperial threads but used metric bearings.

Restoring continental machinery is almost dull by comparison 😄
 
I now have a wooden nut. A 4mm hole (wood bit was too loose. I used a 3mm drill and got some good bite. So a temporary fix while I try to identify the thread. That means that I don’t risk losing the other small parts in the meantime. Thanks Ian.
 
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