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[dennisw100]

What exactly are 'BA' bolts?

Read a lot about them on here and other things regarding models and obviously they're small nuts and bolts, but what's BA all about? I mean bolts are normally just in mm, like 3mm bolts?

I mean 14BA is obviously tiny, but where does the 14 come from? 1/14 of an inch or something?

[anmo]

Oh dear, oh dear. I'm guessing that you're fairly new to this game. BA stands for British Association, and though a bit 'old fashioned' is still very widely used where small fine threads are needed. Although metric threads of various kinds dominate today, there are many other types of screw thread still in widespread use in 2006. BA (British Association), BSF (British Standard Fine), BSC (British Standard Cycle Thread), CEI (Cycle Engineers Institute), ISO (International Standards Organisation) Metric Coarse, Fine, and Special Pitch, UNF (Unified Fine Thread), UNC (Unified Coarse Thread), and Whitworth Threads. I do use metric threads, but for modelling use have found BA and UNF to be the most suitable.

[dennisw100]

Yeah fairly new, hence the question. Knew about most of the other thread types through my automotive experience.

So BA is another thread type, no problem.

How do the sizings work? Higher the number smaller they are?

I'll have to pop to my local fixings place, they keep every variation of thread, material and tool fitting upto 72mm nuts and bolts in stock! Will have to see what they can get me.

[anmo]

I think you'd be lucky to find small BA stuff at most fixings suppliers Dennis, but most decent model shops, or even better model engineers' suppliers should have them, look in your Yellow Pages. A lot of small BA nuts & bolts are available in brass, which is good for boats, as it does away with the rust problem. Try to find a supplier who doesn't sell them in tiny pre-packaged quantities though, as that makes them expensive.

[Shipmate60]

Blimey, are you still using BSF, must be on old equipment then!!!

Bob

[RickF]

I can unreservedly recomend these guys - Folkestone Engineering Supplies - no minimum quantity and a return of post service. http://www.metal2models.btinternet.co.uk/index.htm

Rick

[Made it to 80 (25p Richer now)]

The fact that Ammo is still useing stuff that old must surely be a tribute to the system ..............he said whilst looking for his pension book
                         Cheers
                              Bob B ::) ::)

[dennisw100]

I think you'd be lucky to find small BA stuff at most fixings suppliers Dennis

Well they might not keep it in stock but they can get pretty much anything, even have obscure stuff made if you want it bad enough.

They have a display under their counter with a whole line of bolts from those so small you can barely see them to some as thick as your arm. Then the same with nuts, if you dropped the smallest nut, you'll never see it again, if you dropped the biggest, you need a new floor.

point taken though.

[colin-stevens]

try getting realy small metric sizes. there is no equivelent to a 14ba or 16ba for example, a size that is realy usefull at rhe scales we tend to work in.
bring back the steam engine.

[chromedome]

i thought that B.A.stood for British Admiralty (fine).No? :-\

[dennisw100]

there is no equivelent to a 14ba or 16ba for example

So what size are 14 and 16ba? they must have a measurement, metric or imperial.
I mean how do you know what size you need?

Like if you had a ba bolt of unknown size and needed a nut for it you could measure it with a micrometer or similar and that'll tell you the size in mm's or as a fraction of an inch. so how would you translate that to a ba size?

[Daryl]

WH Smith stock a wonderful booklet called Zeus Precision Data and Measurement Charts. Mine is a bit old and tatty but in there it lists BA sizes from 0 to 12 along with tapping and clearance drills. It has a black and yellow cover and costs around ?5. I find indespensable as it is full of useful information.

Hope this helps
Daryl

[Tug]

A 16 BA is about the thickness of a needle, ?try turning that on your lathe
2 BA is nearly 5mm 4 BA is along the lines of 4mm then 6, 8, 10, 12, totally left the mm's behind allready,

I remember when I dropped a nut and could find it again, would have to be a 1/2" whit. now to even stand a chance.

[maninthestreet]

some more detailed info on thread types:

http://www.boltscience.com/pages/screw1.htm

[anmo]

That's a useful website MITS, though I didn't like the bit about BA threads being 'redundant'. I have an old handbook similar to darryl's, and that's where I got some of the info in my first post from, like I said I rarely use anything other than metric or UNF threads, with BA for all the small stuff. I'm not anti-metric, but I have stocks of BA as well as taps & dies, and as it works really well for modelling applications, I've just kept on using it. The fact that the 'redundant' BA thread is still so widely used, proves that an awful lot of others agree with me on that score.

[dennisw100]

A 16 BA is about the thickness of a needle, ?try turning that on your lathe
2 BA is nearly 5mm 4 BA is along the lines of 4mm then 6, 8, 10, 12, totally left the mm's behind allready,

I remember when I dropped a nut and could find it again, would have to be a 1/2" whit. now to even stand a chance.

Ahh right so the larger the number the smaller the fitting.

then 6, 8, 10, 12, totally left the mm's behind allready

well you can just go into decimals.

The Zeus precision data book sounds like a plan.

[Daryl]

if WH Smith has not got a copy you could try, Maplin, Farnell, RS Components or any engineering supplies store.

Good hunting I am sure you will find it very useful like tables for centreing holes etc.

Daryl

[wideawake]

Rather late finding this thread I know but in case anyone is still set to notify - BA stands for Brirish Association and there is a list of dimensions here

http://homepages.tesco.net/~A10bsa/bago.htm

Cheers

Guy

[Tug]

Good on yer Guy,

looking for a nut for the motor adjusting stud on lathe dismantled for moving, can't find nuts and bolts for re-assembly and going daft.

where over here [France] (postage)  do I get whitworth bolts,

but the 22 tpi @ 5/16" really getting to me, non found, (its BSF) perhaps modified many years ago
the amount of bolts I peered at with glass to count threads making me gozzy,- and groggy.

[wideawake]

Hi Tug

Yes I see the problem.   You could screw cut one on the lathe but you can't do that 'til you reassemble the lathe for which you need the nut   Chicken and egg!

Is the postage really extortionate to France?

Cheers

Guy

[BarryM]

As most of my small taps/dies are still BA, I use BA when possible and avoid the expense of converting to metric. Someday I may have to but not yet. BA nuts, bolts, washers, studding and most socket head screws are still readily available except for 8BA socket head. The latter are like hens' teeth and it was only by chance that I acquired a supply; the current project wouild have been seriously hit if I had not. Matbe I'll have to rethink metric.

Barry M

[Bee]

Few things not been said yet:
BA threads were declared obsolescent back in about 1953 but people wouldn't stop using them so they tried again in the sixties and still we won't obey.

These threads are METRIC even though it is a British standard. That's why no dimension is a nice round imperial number.They were adopted from a Swiss clock making series and all the BA did was formalise the specification and the name stuck.

0BA is very close to M6x1 metric though not exactly and the form is different.

Each size thread pitch is the size above/0.9  and the diameter is a constant factor of the pitch which I can't remember. Now I might have got that slightly wrong but it means the table of threads in one of the sites above is several thou out but I think there is a regular rounding effect applied as when it was standardised I doubt they expected people to do the calculations in excel.

Lots of old electrical equipment uses BA throughout the world. Large numbers of things from China and India still use BA which probably means its use is actually increasing rather than decreasing.
Suprising that an automotive engineer hadn's come across them - The insides of alternators in Rover group products were BA up to 10 years ago and maybe beyond but that's my newest vehicle.

[Bee]

Sad person that I am I found a few pages of BS 93:1951  in my records.
Threads are defined up to 25 BA
starting with 0 BA pitch (p) 1mm,

each numbered (n) thread in the series  p = 0.9^n rounded to 2 places in mm
diameter = 6*p^1.2
so the website is a bit out.

anyone got a 25BA tap : diameter 10 thou, 363 tpi.

[catengineman]

If I had I would not even be able to see it  :'(

I have a few BA  taps and fewer dies mainly from dear old dads tool box though I have kept them just in case I need them ? ::)

R,   

[chingdevil]

I have taps and dies from 0 down to 12 BA but have not used them for many years. 25BA blimey , that is a hair with a twist in it.


Brian