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Fat head BSW screws

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Jelly

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I may have some in the workshop that you're welcome to, I'll need to have a look in the gigantic bag of mixed BSF/BSW fixings to find them though.

They can still be bought, although if "Fat Head" means you want the larger pre-war head dimensions that will be hard to source.

I'd try UK Fixings on Shepcote Lane in Tinsley if I was in your shoes, they've been able to help me out in the past with BSW items despite not listing them on the website, phone number is 0114 243 8080.
 

Taul Paul

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Ta
I can ride past there on mi way home. I guess they are pre war. They are smaller AF but taller (fat). They are off this vice that I'd like to date as near as.

Thanks
Paul in Sheffield
 

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Jelly

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Ta
I can ride past there on mi way home. I guess they are pre war. They are smaller AF but taller (fat). They are off this vice that I'd like to date as near as.

Thanks
Paul in Sheffield
Effectively, during and after the war everything went to the BSF head size, effectively shrinking all the heads of BSW bolts by one size, (pre-war BSF 5/16 would have the same AF as BSW 1/4), so it should be easy enough to tell by comparison with a chart or bsf labeled spanner.

If you don't have any luck with UK Fixings let me know and I'll see if I can look you any out.
 

Cheshirechappie

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For 5/16" BSW bolts and setscrews, the standard head dimensions are as follows;

Precision hexagon bolts and setscrews to BS1083:1951 -

Width across flats 0.525 max 0.518 min.
Head thickness 0.22 max 0.21 min

Bright hexagon bolts and setscrews, old standard BS190:1924 -

Width across flats 0.600 max 0.595 min
Head thickness 0.27 max 0.26 min

Black bolts BS916:1953

Width across flats 0.525 max 0.515 min
Head thickness 0.218 max 0.198 min

Black bolts, old standard BS28

Width across flats 0.600 max 0.580 min
Head thickness 0.29 max 0.27 min

All dimensions are in inches. Info taken from Machinery's Screw Thread Book, 19th edition, 1965.

If the dimensions don't accord with any of the above, they're specials.
 

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