Lister D threads

[gerrybongo]

Hi , the more i research this the more confused i get . I want to clean a pulley lock bolt thread out and thought i would get a small tap+die set , But do i get a BSF or BSW , I can find loads about whitworth spanner sizes but that's easy find a spanner that fits but nothing about actual threads unless in contradiction as to which . thanks gerry

[mecman]

Hi Gerry
Re threads, You need to ID the dia of bolt  and check threads per inch using thread gauges if you have some,but basically  they are BSF British Standard fine or BSW British Standard Whitworth. For the same DIA bolt the Whitworth thread will use a larger spanner size than the BSF as it has a more coarse thread (less threads per inch and deeper cut or core DIA).BSF= fine thread. BSW= coarse thread.Hope this is of some help to you.A thread chart is very handy .You can check threads per inch against dia of bolt and it will ID tap or die size for you.
Mecman (Norm) 

[gerrybongo]

Thanks , so the confusion is there is both BSF BSW threads on them so in short need 2 sets ,

[mecman]

Hi gerry.
I think the old listers were mostly BSW(coarse thread) I run a 1960s petters PH2 and its mostly BSF I only buy taps for whatever job its needed for as they are easily available.1/4- 5/16- 3/8 etc very common.EG A 3/8 BSW has 16 TPI. A 3/8 BSF has 20 TPI (threads per inch).I get my taps from JLS Supplies LTD stroud glos, very quick delivery no probs __(www.engineering-supplies.com)If your spanner has 5/16 BSW 3/8 BSF on it_ it fits as it says so check DIA of bolt . OK thats me screwed for now.  
Good luck_ Norm 

[gerrybongo]

Hi Norm , ive just ordered a cheap BSW set for the amount i shall be doing and i will pick the odd BSF taps off the E@@@ , . Decent taps are as much as the set i got , But i will check out engineering supplies for the BSF , and a good tip with the spanner size and count the threads , my spanner days were many years ago its amazing how rusty you become .

[mecman]

Gerry.
I thought my spanner days were over when lord Nelson was a cadet just shows you never know.
Norm.  

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