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BA sizes

Is 4BA the same as 1/4 inch hex?

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Dr. MC Black10/05/2021 19:43:48
234 forum posts
1 photos

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

John Haine10/05/2021 19:49:53
4086 forum posts
241 photos

Have you got a caliper? If so measure it.

Balljoint10/05/2021 20:02:34
37 forum posts
12 photos

4 BA is 0.248, so near as you can get

Mark Rand10/05/2021 20:13:25
1050 forum posts
11 photos

Across flats for 4BA hexagon is 0.249", so fairly close to 1/4" cheeky.

Mark Rand10/05/2021 20:14:59
1050 forum posts
11 photos

Looks like ±1 thou according to sources...

Nigel Graham 210/05/2021 21:14:34
1661 forum posts
20 photos

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

br10/05/2021 21:18:43
697 forum posts
3 photos

Loads on EBAY

example

Vintage Steadfast Long Reach 4BA Nut Spinner

£2.50  0 bids

or Best Offer

+ £2.45 postage

John Haine10/05/2021 21:25:53
4086 forum posts
241 photos

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

Michael Gilligan11/05/2021 00:20:16
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18698 forum posts
912 photos
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.

Dr. MC Black11/05/2021 00:58:03
234 forum posts
1 photos
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.

Dr. MC Black11/05/2021 01:10:13
234 forum posts
1 photos

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?

Bill Phinn11/05/2021 02:33:45
559 forum posts
86 photos
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".

Speedy Builder511/05/2021 06:42:43
2383 forum posts
181 photos

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

Michael Gilligan11/05/2021 06:50:30
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18698 forum posts
912 photos
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

JasonB11/05/2021 07:13:47
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Moderator
21284 forum posts
2416 photos
1 articles

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

Michael Gilligan11/05/2021 07:59:43
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18698 forum posts
912 photos

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

Dr. MC Black11/05/2021 10:04:41
234 forum posts
1 photos
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

MadMike11/05/2021 13:01:31
223 forum posts
4 photos

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.

Michael Gilligan11/05/2021 13:11:42
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18698 forum posts
912 photos
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

elanman11/05/2021 13:31:07
36 forum posts
3 photos

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

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