Seeking a nut for my dad's old tool

[DrPhill]

I had a use for one of my dad's old tools the other day and noticed that it was missing a nut. What are the chances of identifying and replacing it? Anyone know how I would go about this? Any good web sites?

Yes I know it is old, bent and not digital..... but it was handy when evening out my walking stick shaft. (And it doesn't need batteries)

Any help gratefully received.

 

[Alpha-Dave]

I’m certain I have a set of callipers like that that I’ve not seen in ages, I will have a look later to see if they are the same. However, this is also a good opportunity for you to add to you tool kit.

You can buy folding thread gauges from eBay of banggood for a couple of £ that will tell you the exact thread pitch you want whether metric or imperial, then just check the diameter and order a couple of whatever size you need from one of the many eBay sellers that supply singles of obscure nuts and bolts. If it turns out to be m3 or m4, buy a 50 pack from Screwfix or Toolstation for the same cost.

Given that the picture shows it to be about 2mm in diameter, there is a reasonable chance it is a m2 metric screw thread.

 

[Trevanion]

Being that old there’s almost nil chance of it being metric. I would assume it’s either a BA or BSF thread. Have you got a way of accurately measuring the diameter of the thread and how many threads per inch there is?

 

[CHJ]

Can you measure the diameter reasonably accurately and the thread count Phill.
Some of us have an accumulation of BA and odd ball threads squirreled away over the years.

Pity you are not a bit neared Gloucestershire you could waste an hour sifting through some or possibly making a replacement.

 

[whatknot]

I assume you do not have jars/boxes/drawers full of myriads of nuts as most blokes seem to hoard (guilty)

So why not just change the whole bolt and nut ?

 

[Trevanion]

I’ve got a similar calliper to hand so I checked the thread of that which worked out to be 8ba. Whether that’s the same as yours I wouldn’t know for certain.

 

[Sheffield Tony]

Measuring from the posted image, 8BA is the closest match I agree - unless it is something obscure like Whitworth instrument thread, in which case you have a problem.

 

[AES]

I have one very similar to the one shown above. As the OP says, they're great because not only do they not need any batteries but also because they don't need to "measure" (in numbers) anything at all - in most cases you just set the jaws to be a nice sliding fit over your "master" and transfer that "space" to the job.

Very useful bits of kit. I have 2 actually, one about 6 inches long, the other about 9 or 10 inches long. Both are yonks old (I inherited them from my Dad), one is CK Jens brand, the other unknown/unmarked/worn off. Both mine have 8 BA lock nuts.

Like CHJ, I've got quite a few in my "BA nuts & bolts box" (I bet his and mine came from very similar places!) so if, as sounds likely, yours is 8BA too, then send me a PM with your full postal address and I'll pop a couple in the post for you.

 

[CHJ]

 

[DrPhill]

You can buy folding thread gauges from eBay of banggood for a couple of £ that will tell you the exact thread pitch you want whether metric or imperial

It is almost certainly imperial (none of your metric stuff on the measuring side - just good old inches and parts. Not even tenths of an inch. The thread gauges on eBay seem to be whit worth/metric - would these be what I want? Not sure if I could justify a purchase though - into my seventh decade and this is the first time I have thought I might use one.

For the relative costs I think I would rather speculatively purchase some 8BA nuts, and if I am wrong donate the lot to some collector on here.

I have one very similar to the one shown above. As the OP says, they're great because not only do they not need any batteries but also because they don't need to "measure" (in numbers) anything at all - in most cases you just set the jaws to be a nice sliding fit over your "master" and transfer that "space" to the job.

Exactly - I have a thing that I call 'natural measurement', though there is probably an official name for it. If I possibly can I measure one thing against the other directly. Or in this case adjust the calliper and use the calliper. Converting to an approx measurement in numbers and back again seems to be asking for errors. I will often cut a piece deliberately over (if necessary) then offer it up to transcribe the measurement directly onto the thing to be cut. I tend to avoid mils or sixteenths or whatever.

I assume you do not have jars/boxes/drawers full of myriads of nuts as most blokes seem to hoard (guilty)

So why not just change the whole bolt and nut ?

....oops, I am letting down the gender stereotypes here.

 

[sunnybob]

This might help;
https://www.ba-bolts.co.uk/faq.html

 

[Myfordman]

Being that old there’s almost nil chance of it being metric. I would assume it’s either a BA or BSF thread. Have you got a way of accurately measuring the diameter of the thread and how many threads per inch there is?

Of course ba threads are metric based. The pitch is 0.9 mm raised to the power of the ba number. Eg 2ba is 0.81 mm pitch and so on.

 

[Trevanion]

Of course ba threads are metric based. The pitch is 0.9 mm raised to the power of the ba number. Eg 2ba is 0.81 mm pitch and so on.

Huh, the more you know! I always thought they were a really early imperial thread for very precise instruments and the like but I've never really looked into it too much.

 

[AES]

They were Myfordman, "designed" mainly for instruments as you say, and also (especially when made of brass) for domestic electrical gear. But Trevanion is also right, the BA series of nuts and bolts is indeed sort of metric based, with a specific "decimal relationship" between each diameter and pitch. The series was originally designed (for the British Association would you believe!) by the National Technical High School ("ETH" in Swiss German) who are (still) based in Zurich.

Just to avoid any doubts, that job was done just a few years before I moved to Switzerland in 1990 (I think ETH did the job in about 1870!)

There's still a fair bit of BA stuff to be found around today, but especially in domestic electrical fittings etc, over here anyway, it's been largely superceded by stuff like 2.0, 2.5, and 3.0 mm (all Metric Fine threads). BA equivalents of those 3 are 8, 6, & 4 BA.

 

[profchris]

BA is the thread on 1920s Windsor banjos - I think it was a forum member who put me on the track of the 6BA machine screws I needed.

Be reassured that all the wrong size screws I bought have been thrown into a jar without any labelling, thus preserving the bloke stereotype.

 

[DrPhill]

Thank you Chas, all sorted now.

The supplied screw/nuts were slightly larger than the existing screw.... but a small amount of filing enlarged two of the three of holes and I replaced the old screw as well. The increase in tension on the spring improved the 'feel' and the locknut means it won't loosen.

Again, thanks. Another favour to pay forward, though after many years of this it has become an attitude of mind rather than an accounting excercise.