BA sizes

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BA sizes

This topic has 88 replies, 20 voices, and was last updated 15 May 2021 at 14:46 by Dr. MC Black.

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10 May 2021 at 19:43 #544314
Dr. MC Black
Participant
@dr-mcblack73214
I have nut spinners for 0BA, 2BA and 6BA but I have NOT been able to purchase a nut spinner for 4BA (at a reasonable price).

I have looked at the data, and that suggests that 4BA is very similar to 1/4 inch A/F

Is this a reasonable inference?

MC
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10 May 2021 at 19:43 #10830
Dr. MC Black
Participant
@dr-mcblack73214
Is 4BA the same as 1/4 inch hex?
10 May 2021 at 19:49 #544315
John Haine
Participant
@johnhaine32865
Have you got a caliper? If so measure it.
10 May 2021 at 20:02 #544317
Colin Harwood
Participant
@balljoint
4 BA is 0.248, so near as you can get
10 May 2021 at 20:13 #544319
Mark Rand
Participant
@markrand96270
Across flats for 4BA hexagon is 0.249", so fairly close to 1/4" .
10 May 2021 at 20:14 #544321
Mark Rand
Participant
@markrand96270
Looks like ±1 thou according to sources…
10 May 2021 at 21:14 #544329
Nigel Graham 2
Participant
@nigelgraham2
I'm a bit surprised you could not find BA nut spinners or similar. Have you tried Chronos or ModelFixings? They may have them.
10 May 2021 at 21:18 #544330
Former Member
Participant
@formermember12892
[This posting has been removed]
10 May 2021 at 21:25 #544333
John Haine
Participant
@johnhaine32865
Get an imperial Allan head bolt with 1/4" socket.
11 May 2021 at 00:20 #544346
Michael Gilligan
Participant
@michaelgilligan61133
Posted by John Haine on 10/05/2021 21:25:53:

Get an imperial Allan head bolt with 1/4" socket.

.

… or just use the handle from a 1/4” hex drive screwdriver set

MichaelG.
11 May 2021 at 00:58 #544349
Dr. MC Black
Participant
@dr-mcblack73214
Posted by Nigel Graham 2 on 10/05/2021 21:14:34:

I'm a bit surprised you could not find BA nut spinners or similar. Have you tried Chronos or ModelFixings? They may have them.

I have tried both; Chronos does NOT sell nut drivers and Model Fixings do NOT have BA sizes in their range – only metric.

But Very many thanks for the suggestion.
11 May 2021 at 01:10 #544351
Dr. MC Black
Participant
@dr-mcblack73214
I have tried using a 1/4" screwdriver bit handle but the 4BA nuts do NOT seem to be a consistent size. Some fit but others do not, even though they all have a 4BA thread.

Can anybody tell me what size Cap head screws have a 1/4" socket in the head, please?
11 May 2021 at 02:33 #544352
Bill Phinn
Participant
@billphinn90025
Posted by Dr. MC Black on 11/05/2021 01:10:13:

Can anybody tell me what size Cap head screws have a 1/4" socket in the head, please?

Some 5/16" UNC and UNF have a 1/4".
11 May 2021 at 06:42 #544356
Speedy Builder5
Participant
@speedybuilder5
Make your own up, bit of tube (drilled out to the suit), heat it up and force some steel 4BA nuts down the tube, adjust the fit by hammering to shape. That way, you can make them "deep" to accommodate nuts that are spun onto threaded rod further than the "normal" amount.

I have used car radio Ariel telescopic tube for 8 and 10 BA tubular spanners.

Bob
11 May 2021 at 06:50 #544357
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Dr. MC Black on 11/05/2021 01:10:13:

I have tried using a 1/4" screwdriver bit handle but the 4BA nuts do NOT seem to be a consistent size. Some fit but others do not, even though they all have a 4BA thread.

[…]

.

If some of the hexagons are over-size, then it seems you are ‘on a hiding to nothing’

… You need to find whatever wrongly sized socket happens to fit them.

MichaelG.

.

Edit: __ maybe useful link

https://www.ba-bolts.co.uk/faq.html

Edited By Michael Gilligan on 11/05/2021 06:51:42
11 May 2021 at 07:13 #544359
JasonB
Moderator
@jasonb
Get a 4BA box spanner and Loctite or solder on your own extension handle.

4 BA socket and a 1/4" drive "screwdriver" handle work for me in most cases changing to a box spanner if room is tight.

Edited By JasonB on 11/05/2021 07:15:45
11 May 2021 at 07:59 #544367
Michael Gilligan
Participant
@michaelgilligan61133
Here’s another useful reference page: **LINK**

https://www.fastenerdata.co.uk/fasteners/nuts/hexagon-full/ba/ba-hexagon-full-nut-brass-bs57.html

Note that there is a common theme emerging :

Anything greater than 1/4” AF is not compliant with BS 57:1951 and is therefore ‘out of spec.’

There, of course, is no law against making ‘specials’ … but you must expect to need a special spanner.

MichaelG.

.

Ref: https://shop.bsigroup.com/ProductDetail?pid=000000000000010735

Edited By Michael Gilligan on 11/05/2021 08:11:25
11 May 2021 at 10:04 #544383
Dr. MC Black
Participant
@dr-mcblack73214
Posted by Michael Gilligan on 11/05/2021 06:50:30:

Posted by Dr. MC Black on 11/05/2021 01:10:13:

I have tried using a 1/4" screwdriver bit handle but the 4BA nuts do NOT seem to be a consistent size. Some fit but others do not, even though they all have a 4BA thread.

[…]

.

If some of the hexagons are over-size, then it seems you are ‘on a hiding to nothing’

… You need to find whatever wrongly sized socket happens to fit them.

MichaelG.

.

Edit: __ maybe useful link

**LINK**

Thank you for taking the time to post.

Actually the nuts are smaller than the 1/4 driver.

The BA-bolts data is interesting – on both of the sites for which links are provided, the figures are in inches – but I was told years ago that BA is actually defined in Metric.

When I find useful data, I like to print it, laminate and keep in workshop. Sadly both the tables are NOT in an easily printable format.

With best wishes and thanks again.

MC
11 May 2021 at 13:01 #544414
MadMike
Participant
@madmike
Ebay has plenty of 4BA nut spinners. However if you have hex heads that do not conform then check that you have a genuine BA bolt. You may find that some of todays suppliers fo bolts are using a more readily available metric or Imperial A/F hexagon bar. I have 4BA open ended, ring and box spanners and they all are perfect fits on genuine 4BA hex heads. If you find nut spinners do not fit then try a long reach box spanner which will probably be 4BA one end and 2 BA the other.

BA threads are originally based on the Swiss or Thury thread with a thread included angle of 47 degrees and 30 minutes. Thus the thread depth is less that the 55 degree Whitworth thread form. HTH.
11 May 2021 at 13:11 #544416
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Dr. MC Black on 11/05/2021 10:04:41:

Posted by Michael Gilligan on 11/05/2021 06:50:30:

Posted by Dr. MC Black on 11/05/2021 01:10:13:

[…]

.

Apologies … I misunderstood your “Some fit but others do not …”

It is not uncommon for BA nuts and bolts to be supplied with under-size spanner flats.

As regards the BA system calculations: Yes, the calculation was derived from an existing metric system; but the British Association for the advancement of Science was Imperial to the core !!

MichaelG.

.

P.S. __ BS 57:1951 actually tabulates all the values in both systems of units.

Edit: this is worth a look:

https://en.wikipedia.org/wiki/British_Science_Association

Edited By Michael Gilligan on 11/05/2021 13:19:57
11 May 2021 at 13:31 #544419
elanman
Participant
@elanman
Are some of the nuts made with the one size smaller hex bar to make the nuts look more in scale. So a 4BA nut would be made with a 5BA hex size. Kennions still sell these and also bolts.

Cheers

John
11 May 2021 at 13:32 #544420
Former Member
Participant
@formermember12892
[This posting has been removed]
11 May 2021 at 13:36 #544422
elanman
Participant
@elanman
Are some of the nuts made with the one size smaller hex bar to make the nuts look more in scale. So a 4BA nut would be made with a 5BA hex size. Kennions still sell these and also bolts.

Cheers

John
11 May 2021 at 13:44 #544423
Dr. MC Black
Participant
@dr-mcblack73214
Very many thanks to everybody for their comments

I will manage with a 1/4" Screwdriver Bit handle for the time being.

The cost of postage often makes buying things from Ebay uneconomic – apart from NOT knowing if any descriptions are fair and accurate.

I recently bought a book from an overseas bookseller – although he described it as "Acceptable" many of the pages had been scribbled on and I told him that a fair description would be "Poor". The stress of doing this has convinced me to be VERY cautious about buying anything by Mail Order from anywhere, especially from overseas.
11 May 2021 at 22:07 #544504
bernard towers
Participant
@bernardtowers37738
4ba nut spinner. Come on lads you’ve missed a trick, make it from a socket head with a 1/4 socket.
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