Ideas on how to make a 7BA tubular box spanner

[GreensandsParticipant @greensands]

Can anyone suggest a simple way of making up a 7BA tubular box spanner as sold by our various suppliers. My usual technique of making use of a suitable socket headed screw doesn’t apply in this instance as the fit falls between the commonly available 5 and 6mm screw heads.  Any suggestions most welcomed.

[bernard towersParticipant @bernardtowers37738]

Find a socket headed screw of the correct size or very close and fit a handle

[martin haysomParticipant @martinhaysom48469]

buy one from ebay

[BazyleParticipant @bazyle]

File or mill flats on a steel rod to the 7BA AF dimension plus a bit of clearance for say 3/8″ length.
Turn down the last 1/4″ to a taper down to just under 7BA dia.
Then drill a bit of brass rod 7BA clearance right through. Turn the outer dia to about 7BA+60thou for only 1/8″.
If the brass isn’t nice and soft anneal it.
Hammer the steel hex into the brass hole. Then you will need a steel rod or nail to hammer it out again which is why you drilled all through initially.
Harden the brass by heating and quenching.

Alternatively drill with a hex drill, look up drilling square holes.

[howardbParticipant @howardb]

Find and buy a 7 BA long socket 1/4″ square drive?

[John HaineParticipant @johnhaine32865]

Halfords stock 4.5mm a/f 1/4″ drive sockets. 7 ba nout is 4.37mm after so should be a reasonable fit.

[duncan webster 1Participant @duncanwebster1]

You can’t harden brass by heating and quenching, in fact that would soften it.

There is a set of BA sockets on ebay at thd moment for £11

[Paul LousickParticipant @paullousick59116]

Why make one ?? There are lots advertised on ebay.

[Speedy Builder5Participant @speedybuilder5]

I used a bit of telescopic Ariel tube and similar to Bazyle swaged it to fit the 7Ba head. I needed a very thin box spanner as the bolt heads nearly touched each other.

Bob

[noel shelleyParticipant @noelshelley55608]

Use a 7BA brass bolt head as the electrode (cutter ) and spark erode into whatever metal you wish – even carbide ! This will create the socket, now machine away to the outside to the shape you want. Or just buy one ? Noel.

[OldironParticipant @oldiron]

Would an imperial cap screw with a 7/32 socket head be close enough ?

[GreensandsParticipant @greensands]

I would be quite happy to buy a spanner but I have not found the style I am looking for. The photo is of one I picked up at an exhibition some time ago buy have not found a current supplier. Any suggestions as to whom might be worth trying?

[Andy StopfordParticipant @andystopford50521]

Pollymodels do one that’s similar – I don’t know what they’re like.

Beware, many of these now seem to have almost totally unformed ends, I bought a set where all the smaller ones needed a hexagon filing out from what was more or less a round hole in the end.

[Michael GilliganParticipant @michaelgilligan61133]

I have no idea of the quality … but this set might be an investment:

https://www.lasertools.co.uk/Product/6196/BA-Deep-Socket-Set-1-4-inch-drive-9pc

MichaelG.

.

P.S. __ a useful tabulation of BS57 dimensions here:

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

[Greensands]

On Greensands Said:

I would be quite happy to buy a spanner but I have not found the style I am looking for. The photo is of one I picked up at an exhibition some time ago buy have not found a current supplier. Any suggestions as to whom might be worth trying?

Hi Greensands

I have a part set of those spanners (4,5,6 and 7BA) and very good spanners they are too. Sorry but I can’t remember where I obtained them, not that it would be much help, I’ve had them for more than 45 years.

[Andrew CrowParticipant @andrewcrow91475]

I got mine from Reeves when they were in Marston Green, it may be worth checking their website as they might still stock them.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Greensands, EKP, do a set. EKP box spanner set.

If you just want a 7BA Chronos 7BA box spanner

 

Regards Nick.

[GreensandsParticipant @greensands]

I think that Nicholas has come up with the answer i have been looking for. Thanks to all who have contributed. 

[John HaineParticipant @johnhaine32865]

Shame they don’t do metric!

[paul rushmerParticipant @paulrushmer83015]

John I think polly do metric as well, I think they possibly make them themselves.

Paul

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