bsf thread

1/ 4 BSF should have an across flats measurment of 0.445" or 11.303mm. for practical purposes it is probably close enough as most bolt heads measure a shade under size.(assuming you have hex bar)

Mike

Edited By Michael Poole on 17/08/2016 12:26:03

Edited By Michael Poole on 17/08/2016 12:27:12

Not sure what material you want to make the screws from but as far as I know steel is made in a wide range of diameters but not usually described as 'metric equivalent'. You can buy 12mm, 13mm and I have once seen 12.5mm but none are exactly 1/2".

No idea what nuts and screws you got for £2 but as BSF is not a preferred size it could be a good deal.

What has BT wifi got to do with bar diameter?

Ian P

If you are making from round stock then you need a shade over 13mm dia to be able to get the right hex (13.048mm) but in practice 13mm bar will do.

Good old BSF I have just tried to purchase some 3/8 bsf studding for a mod on my Tom Senior, guess how much???

£75.00 for a metre and this was with my company discount at J & L. So a piece of 3/8 bar out of the stores a old 3/8 die and my 6" long studs were made in 10 minutes FOC.

So remember BSF = Better Start Foraging!!!

It's simple enough to buy 1/2" steel round bar. My (commercial) steel stockholder has a variety of grades varying from £3.21p to £4.38p (plus VAT) for 3m lengths. I've also bought 1/4" BSF fasteners, and they were nothing like the prices mentioned? Although it is best to avoid those companies serving the vehicle restoration market, as they seem to have 'how much?' pricing for imperial fasteners.

When I made my own 1/4" BSF nuts (and bolts) I used 11mm AF hex; conveniently I had a 11mm hex collet:

Andrew

Senior - try Cromwell - they have it listed at a tenth of that price, unless what you're after is very exotic.

Nice nuts Andrew. I never knew that BSF/BSW was so rare that you had to make em. Although, I appreciate that yours are a bit fuller than normal and the others "half nuts" ? or lock nuts. Last time I visited Oz, BSF/BSW were quite common alongside metric. I also went to an outboard repair shop, and he had the lot including UNF/UNC, but I suppose Oz is a bit far to go.
BobH

Funny old world! Last week a colleague asked me to make a 3/8 BSF hex head bolt for his brother's old motor (don't know any more than that). They had tried to find one that did not require the purchase of lots of them. I found one that was too long but had a long enough plain section to cut more thread on. Cut off the excess then cut the thread on the lathe and polished the finish with a die nut. He was very happy and at some point I am sure he will be helping me with something I need.

Martin

Hi,

Retired farmer in our village sells almost every thread profile you are ever likely to need BSF - BSW, Metric coarse and fine, UNC/UNF and whatever else you might need. Might not do more exotic threads - cycle etc but has met my needs when ever required.

If you are in need just pm me and I can provide contact details. - he is not on the web.

JD

If you want screws and bolts of either type to be near on size these days buy precision versions. They tend to cost and may only be available in high tensile socket screws of various types.

John

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Thanks Bob, but they're not rare, it's just that the commercial ones don't come anywhere near the standard I expect. I did buy some cheap commercial 1/4" BSF bolts and nuts but they simply didn't 'measure' up. They're now relegated to jigs and fixtures. The nuts, and locknuts, are based on the old Whitworth standards, although the AF dimension was determined by the hex collets I have, and in the case of the 5/16" BSF nuts the available space on the cylinder casting.

Of course having a repetition lathe helps, once set up it is easy to churn out parts quickly. All the nuts shown only took a few hours over a few evenings. And all done with freehand ground HSS tooling, not a jig in sight.

I've also made my own BSF studs and bolts. These are all highly visible parts of the engine, on the cylinder block and motion work, so I want them to stand out. And it allows you to get one over on the rivet counters.

Andrew

Hi Keith, Cromwell are still searching for a length of 3/8 bsf after sending me M10 length twice. Cromwells nice brochure no stock!! Looking forward to fitting my 4" spacer on to my Tom Senior

Cheers

A few years back the compressor at a local engineering shop broke down, a 3/8" castellated BSF nut on part of the valve gear had stripped, they could not find another nut, or a BSF tap(neither could I), so I went home and made a nut and threaded it in the lathe. When I took it back, they were amazed, their lathe operator didn't think it possible, I don't know if he had any qualifications, he definitely had a better lathe than mine, and plenty of tools, I had to make one to do the job, I think that took longer than the job its self. Whitworth, and BSF are not as easy to find as metric, anf UNF/ UNC in NZ, alright if you are in a city, but when you get rural, no go.

Ian S C