Author Topic: 26 tpi threads  (Read 451 times)

Offline roadrocket

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26 tpi threads
« on: 12.07. 2016 14:30 »
1/4'' BSF and 1/4'' BSCY are both 26 tpi. What's the difference?
Otto in Denmark

Online Billybream

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Re: 26 tpi threads
« Reply #1 on: 12.07. 2016 14:58 »
Its the thread angle, hard to distinguish with the naked eye, but thread gauges would identify.
1960 Super Rocket, owned since 1966, back on the road 2012 after being laid up for 29yrs.

Offline roadrocket

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Re: 26 tpi threads
« Reply #2 on: 12.07. 2016 15:08 »
Thanks! Maybe a stupid question, but would a nut from any of the two fit the other bolt?
Otto in Denmark

Offline rocker21

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Re: 26 tpi threads
« Reply #3 on: 12.07. 2016 15:24 »
yes, the difference is so small, for all practical purpose's they will fit,  there are other 1/4 x26 tpi threads that would be difficult to use like BSB (british standard brass) but they are not very common now. the thread angle and the form is different and it would be a tight fit.

Online chaterlea25

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Re: 26 tpi threads
« Reply #4 on: 12.07. 2016 22:55 »
Hi RR
Enough info here to keep you busy for a while  *eek*

http://www.gewinde-normen.de/en/index.html

John
1961 Super Rocket
1963 RGS (ongoing)

Online BSA_54A10

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Re: 26 tpi threads
« Reply #5 on: 13.07. 2016 08:53 »
The trouble is that in place of the threads contacting on their entire face they make a point contact.
Which ever is the harder will deform the weaker and from then on you have what feels like a worn out thread.
It is similar to trying to fit a garden gate galvanised nut onto an electroplated bolt ( and we have all done it at least once ).
Because it is only 1/4 " diameter heavy handed Hank can force the nut to run, once.
Bike Beesa
Trevor