Seatpost binder bolt with threads in the frame
- Thread starter Simon Masterson
- Start date
Simon Masterson
Old School Hero
Re:
Thanks all. The 1/4 inch (not sure if fine or coarse) bolt I have does feel like it wants to go, but I’ve ordered a UNC and a UNF for comparison. I think it’s going to have to be tapped...
Thanks all. The 1/4 inch (not sure if fine or coarse) bolt I have does feel like it wants to go, but I’ve ordered a UNC and a UNF for comparison. I think it’s going to have to be tapped...
torqueless
Senior Retro Guru
Re:
Even re-tapping depends on being pretty sure what tpi you have in there to start with. If there is a tpi discrepancy between the tap and the existing thread you just end up with a big ragged hole..
I guess the coarse M7 Metric tap (25.4tpi) is close enough tpi to 1/4" BSF or BSC (26tpi) to leave a functional thread. Not sure what is going on here:
http://www.merciancycles.co.uk/online-s ... r-tap-kit/
An M8 x 1.25 tap maybe? That would be 20.32tpi?
Or M8 x 1 (25.4tpi)?
If your 1/4" bolt has an inch of thread you should be able to count the threads with your thumbnail- 20(BSW or UNC) 26(BSF or BSC) or 28(UNF)
By the same token you could try taking some sort of 'threadprint' of the female frame thread with a matchstick and some plasticene or somesuch.
Even re-tapping depends on being pretty sure what tpi you have in there to start with. If there is a tpi discrepancy between the tap and the existing thread you just end up with a big ragged hole..
I guess the coarse M7 Metric tap (25.4tpi) is close enough tpi to 1/4" BSF or BSC (26tpi) to leave a functional thread. Not sure what is going on here:
http://www.merciancycles.co.uk/online-s ... r-tap-kit/
An M8 x 1.25 tap maybe? That would be 20.32tpi?
Or M8 x 1 (25.4tpi)?
If your 1/4" bolt has an inch of thread you should be able to count the threads with your thumbnail- 20(BSW or UNC) 26(BSF or BSC) or 28(UNF)
By the same token you could try taking some sort of 'threadprint' of the female frame thread with a matchstick and some plasticene or somesuch.
Simon,
This peaked my curiosity. I have a c1968 Claud Butler "Super Torino" that was made to measure and it also has an odd size bolt in integral seat post binder. Lucky at time that it was still in frame when I received from seller in London. I just removed with a 7/32" Allen key and it appears to be a 5/16", 22tpi BSF. (I'm no bolt aficionado.)
https://en.wikipedia.org/wiki/British_Standard_Fine
Also found this site that seems to have the same bolt, even serrations on head although stainless not black. This is same length as mine - 3/4":
https://britishfasteners.com/index.php/ ... -6250.html
Don't have my calipers with me but... Thoughts? Could this be the same as yours?
Doug
This peaked my curiosity. I have a c1968 Claud Butler "Super Torino" that was made to measure and it also has an odd size bolt in integral seat post binder. Lucky at time that it was still in frame when I received from seller in London. I just removed with a 7/32" Allen key and it appears to be a 5/16", 22tpi BSF. (I'm no bolt aficionado.)
https://en.wikipedia.org/wiki/British_Standard_Fine
Also found this site that seems to have the same bolt, even serrations on head although stainless not black. This is same length as mine - 3/4":
https://britishfasteners.com/index.php/ ... -6250.html
Don't have my calipers with me but... Thoughts? Could this be the same as yours?
Doug
Attachments
torqueless
Senior Retro Guru
Re:
Good that you posted, CBguy, otherwise I would still be wrongly thinking that 5/16" BSF is 26tpi, as 1/4" BSF is. BSC thread seems to keep to 26tpi across sizes: http://stevenott.com/ceithreads.htm
BSF of course does not.
I have edited my last post accordingly.
Your bolt housing is not counterbored to take the bolt head as mine is. Could it be that your style (exposed bolt head) are usually 5/16", and my style (recessed bolt head) are usually 1/4"?
I don't think your allen key can be 7/16". Maybe 7/32"?
Dunno if this is helpful- I compiled this list of likely (and unlikely?) thread suspects, from smallest to largest. I think this is right:
ISO 6mm x 1mm (25.4tpi)
BSW: 1/4 x 20tpi
UNC: 1/4 x 20tpi
BSF & BSC: 1/4"x 26tpi
UNF: 1/4 x 28tpi
ISO: 7mm x 1mm (25.4tpi)
BSW & UNC: 5/16 x 18tpi
BSF: 5/16 x 22tpi
UNF: 5/16 x 24tpi
BSC: 5/16 x 26tpi
ISO: 8mm x 1.25mm (20.32tpi)
At any rate, both CBguy and Torqueless seem to have a BSF binder bolt- one in 5/16" and one in 1/4".
Good that you posted, CBguy, otherwise I would still be wrongly thinking that 5/16" BSF is 26tpi, as 1/4" BSF is. BSC thread seems to keep to 26tpi across sizes: http://stevenott.com/ceithreads.htm
BSF of course does not.
I have edited my last post accordingly.
Your bolt housing is not counterbored to take the bolt head as mine is. Could it be that your style (exposed bolt head) are usually 5/16", and my style (recessed bolt head) are usually 1/4"?
I don't think your allen key can be 7/16". Maybe 7/32"?
Dunno if this is helpful- I compiled this list of likely (and unlikely?) thread suspects, from smallest to largest. I think this is right:
ISO 6mm x 1mm (25.4tpi)
BSW: 1/4 x 20tpi
UNC: 1/4 x 20tpi
BSF & BSC: 1/4"x 26tpi
UNF: 1/4 x 28tpi
ISO: 7mm x 1mm (25.4tpi)
BSW & UNC: 5/16 x 18tpi
BSF: 5/16 x 22tpi
UNF: 5/16 x 24tpi
BSC: 5/16 x 26tpi
ISO: 8mm x 1.25mm (20.32tpi)
At any rate, both CBguy and Torqueless seem to have a BSF binder bolt- one in 5/16" and one in 1/4".
Well my mistake - Allen key my bolt takes is indeed 7/32. I'll edit.
Also my 5/16, 22tpi, 3/4" long BSF bolt is recessed. I just didn't screw all the way in as I have seat post out. See pic.
I have read that Holdsworth was criticized for using odd sizes. Also Simon's Ken Bird frame makes me curious if it takes the same bolt. It would be interesting to know what size bolts are in other "shop" builds of same time. Is the Ken Bird built by brother Alec Bird?
Kilgariff says that Alec Bird did build "trade" frames for the Putney shop, although time is uncertain and the same bolt does not make my frame an Alec Bird build!!! Though, being an ex CB employee I have wondered in past if Bird built my made to measure frame for Putney shop. Although on other hand my frame was "supplied" by GW Stratton's shop and Stratton had Bill Gray, another former CB employee, building a lot of his frames.
Also my 5/16, 22tpi, 3/4" long BSF bolt is recessed. I just didn't screw all the way in as I have seat post out. See pic.
I have read that Holdsworth was criticized for using odd sizes. Also Simon's Ken Bird frame makes me curious if it takes the same bolt. It would be interesting to know what size bolts are in other "shop" builds of same time. Is the Ken Bird built by brother Alec Bird?
Kilgariff says that Alec Bird did build "trade" frames for the Putney shop, although time is uncertain and the same bolt does not make my frame an Alec Bird build!!! Though, being an ex CB employee I have wondered in past if Bird built my made to measure frame for Putney shop. Although on other hand my frame was "supplied" by GW Stratton's shop and Stratton had Bill Gray, another former CB employee, building a lot of his frames.
Attachments
torqueless
Senior Retro Guru
Re:
Thanks for clarifying, CBguy, and for 'going the extra mile' in the first place!
Yeah I'm curious about this too. Of course some frames which didn't start out with this sort of binder bolt housing have acquired it as a 'repair' of a failed pressed steel housing/Campag style bolt, or just as a fairly inexpensive upgrade at (p)respray time, possibly before they were five years old.
Does 'odd' = 'BSF'? Makes me wonder who was doing the criticising and where/when? 'Odd' in what context? I think BA/BSW/BSF would have been the default 'general engineering' threads in the UK, from early 20th century probably more or less until the end of the '70s.
It occurs to me that when this style of binder bolt was the 'new thing' in the UK, British industry was still far from metricisation, and high-ish grade BSF bolts (and taps) would probably have been more easily sourced than any alternative.
A telling quote frome here: http://jag-lovers.org/xk-lovers/library ... ystem.html
" In 1965 the British Standards Institution approved a policy statement urging British industry to regard BSW, BSF, and BA as obsolescent, to be gradually replaced by International Standards Organization (ISO) metric thread."
And note that the word is 'obsolescent', which is different from 'obsolete'. The quote fairly reeks of temporising around the no doubt widespread antipathy to 'going metric'- the upheaval of it and questionable utility of it.
..but those who did 'go metric', willingly or not, were bound to criticise those who resisted, and vice versa.
Anyhow, BSF bolts might have proved a PITA when the machines were exported to the USA- perhaps some folk lost the bolt, or wanted to change the bolt to some boutique titanium thing, and found themselves with a tpi/thread form conflict- but at least the USA is 'imperial'.. Imagine me forgetting to pack a 3/16" Allen key and trying to get my saddle height adjusted in Europe- a 5mm Allen key is about 9thou too big across flats..
Thanks for clarifying, CBguy, and for 'going the extra mile' in the first place!
Yeah I'm curious about this too. Of course some frames which didn't start out with this sort of binder bolt housing have acquired it as a 'repair' of a failed pressed steel housing/Campag style bolt, or just as a fairly inexpensive upgrade at (p)respray time, possibly before they were five years old.
Does 'odd' = 'BSF'? Makes me wonder who was doing the criticising and where/when? 'Odd' in what context? I think BA/BSW/BSF would have been the default 'general engineering' threads in the UK, from early 20th century probably more or less until the end of the '70s.
It occurs to me that when this style of binder bolt was the 'new thing' in the UK, British industry was still far from metricisation, and high-ish grade BSF bolts (and taps) would probably have been more easily sourced than any alternative.
A telling quote frome here: http://jag-lovers.org/xk-lovers/library ... ystem.html
" In 1965 the British Standards Institution approved a policy statement urging British industry to regard BSW, BSF, and BA as obsolescent, to be gradually replaced by International Standards Organization (ISO) metric thread."
And note that the word is 'obsolescent', which is different from 'obsolete'. The quote fairly reeks of temporising around the no doubt widespread antipathy to 'going metric'- the upheaval of it and questionable utility of it.
..but those who did 'go metric', willingly or not, were bound to criticise those who resisted, and vice versa.
Anyhow, BSF bolts might have proved a PITA when the machines were exported to the USA- perhaps some folk lost the bolt, or wanted to change the bolt to some boutique titanium thing, and found themselves with a tpi/thread form conflict- but at least the USA is 'imperial'.. Imagine me forgetting to pack a 3/16" Allen key and trying to get my saddle height adjusted in Europe- a 5mm Allen key is about 9thou too big across flats..
