pappaecho
Well-Known Member
I have a 1/2 inch stainless bolt which connects the rudder post to the tiller handle. It is 12.7 mm so definetely genuine half inch. There are 16 TPI anybody any idea which nut I need? AF, UNF, Whitworth ?
Which thread?
- Thread starter pappaecho
- Start date
srp
Well-Known Member
1/2" BSF has 16 tpi
1/2" BSW has 12 tpi
1/2" UNC has a 0.07962" pitch (12.56 tpi)
1/2" UNF has 0.05" pitch (20 tpi)
12mm metric coarse thread has a 1.75mm pitch (equivalent to about 14.5 tpi)
1/2" BSW has 12 tpi
1/2" UNC has a 0.07962" pitch (12.56 tpi)
1/2" UNF has 0.05" pitch (20 tpi)
12mm metric coarse thread has a 1.75mm pitch (equivalent to about 14.5 tpi)
old_salt
Well-Known Member
Yep 12.7 is 0.500 ins 16 tpi there is no AF, UNC, or Met at this tpi the only Wht is 3/8" so it leaves B.S.F. you have a choice 1/2" or 9/16"as you say it is 12.7 this leaves the only solution to be 1/2"B.S.F. The other factors are:- 1/2" B.S.F. core dia .4200 Pitch .0625" depth of thread .0400" radius .0086" and effect .4600".
OK this is a lode of Eng tech jargon.
Just go for 1/2" B.S.F.
All this can be found in the ZEUS Precision Data Charts & reference tables £1,20 from most good engineering shops or Wholesalers.
OK this is a lode of Eng tech jargon.
Just go for 1/2" B.S.F.
All this can be found in the ZEUS Precision Data Charts & reference tables £1,20 from most good engineering shops or Wholesalers.
paul_williams
Well-Known Member
have you tried BSP? couldn't swear to the dimesions, but last time I had a thread that was close but one knew what it was, it was bsp. (making a Tillerpilot extension rod)
paul_williams
Well-Known Member
sorry, forgot to say 3/8 bsp. you didn't say where the boat came from. the americans have some very strange threads that are close to bsp.
FullCircle
Well-Known Member
If its for the Beneteau in your profile, it will almost certainly be a Metric thread form.
If it is attached or attaching to American equipment then probably UNJF or similar, but nothing matching that TPI.
If its British and from Post War to about 1970, it could be just about anything. But likely 1/2 BSF.
Of course, the bolt may have been replaced in the past with something that fitted, but of indeterminate parentage.
For replacement:
If you go slightly larger (0.518 ins) then 1/4 BSP Straight or tapered would do it. Happy Hunting.
Slightly smaller, then (0.4724 ins) then M12 Coarse or fine would do it. Easy Peasy.
Little bit smaller still (0,4375 ins) gives you 7/16 UNC, UNF American or 7/16 BSW or BSF. Easier to find, but not a doddle.
If it is attached or attaching to American equipment then probably UNJF or similar, but nothing matching that TPI.
If its British and from Post War to about 1970, it could be just about anything. But likely 1/2 BSF.
Of course, the bolt may have been replaced in the past with something that fitted, but of indeterminate parentage.
For replacement:
If you go slightly larger (0.518 ins) then 1/4 BSP Straight or tapered would do it. Happy Hunting.
Slightly smaller, then (0.4724 ins) then M12 Coarse or fine would do it. Easy Peasy.
Little bit smaller still (0,4375 ins) gives you 7/16 UNC, UNF American or 7/16 BSW or BSF. Easier to find, but not a doddle.
old_salt
Well-Known Member
1/4" BSP is 19 TPI. OD .518"
3/8" BSP is 19 TPI. OD.656 =3/16" of an inch bigger that would be no good.
No unf or anf or equivalent matches 16 TPI only 1/2" or 9/16" BSF.
Just if there is any confusion the ZEUS Precision Data Charts & reference tables are £1-20p
3/8" BSP is 19 TPI. OD.656 =3/16" of an inch bigger that would be no good.
No unf or anf or equivalent matches 16 TPI only 1/2" or 9/16" BSF.
Just if there is any confusion the ZEUS Precision Data Charts & reference tables are £1-20p
pappaecho
Well-Known Member
Yup is certainly is 1/2 inch BSF. Looked on the Net and British cars in the 1940's to 60's used BSF bolts..
Contacted a local Morris Minor enthusiast who confirmed that his nuts ( so to speak...) fitted.
So where do I get a stainless version of the nut?
Contacted a local Morris Minor enthusiast who confirmed that his nuts ( so to speak...) fitted.
So where do I get a stainless version of the nut?
VicS
Well-Known Member
[ QUOTE ]
So where do I get a stainless version of the nut?
[/ QUOTE ]
Get a local engineering firm to make one if you can't make one yourself.
Sorry I cant help as I don't have any BSF taps that size and my screw cutting abilities are not good enough It's the sort of thing my father would have made without being asked a second time!
So where do I get a stainless version of the nut?
[/ QUOTE ]
Get a local engineering firm to make one if you can't make one yourself.
Sorry I cant help as I don't have any BSF taps that size and my screw cutting abilities are not good enough It's the sort of thing my father would have made without being asked a second time!
Heckler
Well-Known Member
Is it a beneteau bit?
stu
stu
old_salt
Well-Known Member
You should be able to find a fastenings supplier in your area or an engineers wholesaler the nut needs to A4 or 316 stainless. Swindlers should have them. also ebay has lots of peeps selling packs of mixed SS but you will need to be sure you get a pack with BSF in it and not just all metric. Worth it just to have an assortment of sizes. I hope this helps.
VicS
Well-Known Member
I think it will be difficult to find one of these which is why I suggested finding someone who could make one. For use where you say either A2 or A4 will be equally satisfactory.
It might be worth calling into Sea Teach in Emsworth as they do have a good range and you can buy just one when that is all you need and they are in your area.
If it is just to fit on a bolt why not replace the bolt as well with a readily available size M12 will be a bit small but you should be able to find ½" UNF. I think Sea Screw list them. Or drill out the holes to take the next metric size.
It might be worth calling into Sea Teach in Emsworth as they do have a good range and you can buy just one when that is all you need and they are in your area.
If it is just to fit on a bolt why not replace the bolt as well with a readily available size M12 will be a bit small but you should be able to find ½" UNF. I think Sea Screw list them. Or drill out the holes to take the next metric size.
