Where can I get a 3/6" CEI tap ?

[Ixion]

Indeed, CEI taps and dies generally. Y'know the ones, Cycle Engineers Institue, same as BSF, but finer thread and a different thread angle. The very fine bolts used on Triumphs and such like.

All the silly young twits in the engineers merchants seem never even to have HEARD of CEI threads (dunno WHAT they teach them in school now) and try to tell me that bicycles have metric threads. Which they do, of course, but DIDN'T, if you follow me.

Anyway , anyone know a good source?

(I'll swear I have one, but I'm buggered if I can find it)

EDIT: Should have said - plug tap. EDITY EDIT - Arggh. It should be 3/8" of course. Serves me right for typing late at night, and I can't change the title. Grrr.

[Madness]

I was a silly young twit working for different Engineers merchants for 15 years. I have never heard of this thread form either.

Try Trade Tools if you haven't already. They are pretty much the only people importing non-bog-standard-sell-10-a-day threading tools. Most Engineers merchants end up buying from Trade Tools at some stage for this (only) very reason. British Spares might be worth a phone call/email too. Other than that try Tardme?, might sound silly, but there's bound to be a few in sheds, other than that & it's overseas.

Patience & Nicholson in Kaiapoi, now owned by Sutton Tools of Australia used to manufacture all manner of HSS taps. Since the Sutton purchase a few years ago they have been concentrating on Drills for export to Oz. They have ties with F.E.W in South Africa, Trade Tools buy from them also but very rarely are they able to source s.f.a in the way of specials.

[Motu]

I think I had one once - I made the mistake of thinking those square icecream containers would be a good way of storing all my odd taps and dies that don't have a home.However in one of my many moves it must of got a little rain water in there.I think it may be part of the formation in the upper left hand corner.....

[stanko]

Is 3/6" the same as 1/2" ?
How many holes do you need to tap, you could make one or have one made. Or post a question on the Practical machinist website, or the Home Shop machinist site http://bbs.homeshopmachinist.net/ plenty of clever cookies on there

[Ixion]

It should have read 3/8. Too late at night, and I can't edit the title.

I COULD make one I suppose, I can cut CEI threads (They're sometimes called BSC threads) in the lathe, but getting the hardness correct? No, probably not.

Theya re still available in the UK , I was hoping for a local supplier. Trade Tools used to have them when I was into Triumphs, but you had to get the counter guy to get the old guy from the back , he knew what you were talking about. But when I went into Trade Tools to enquire a week ago (they've MOVED, that buggers, not in Federal St any more, always the way, turn y' head and places disappear , Shroffs seem to be the only ones left in the city) the young guy had never heard of CEI or BSC or the old guy either, dunno what happened to him, I guess he didn't want to move.

[sels1]

might have one in our misc taps & dies drawer at work....will have a look...know we have BA and BSF

[imdying]

If you hassle me, I will look in 'the very old workshop'. There's an interesting collection of old taps. 3/8", how many TPI?

[Paul in NZ]

Do you mean British Cycle Thread....

[Motu]

You could use one of my ''tricks of the trade'' if you like....this one is a freebee.If you find a bolt that has a thread pitch pretty close you can just wind it in there - this has a self locking function like Loctite,but better.

[GSVR]

Only cycle thread that I'm aware of is BSC where everything is 26TPI. Must have been back in the days when lathes had change wheels to get the pitch so a one pitch does all appoach would have made alot of sense.


http://www.britishtool.com/bscchart.htm

Do you have a Thread pitch gauge or just count them against a rule? BSC should be pretty easy to get hold of.

[Ixion]

Yes. Also known as BSC (British Standard Cycle) or SCT (Standard Cycle Thread). 26 tpi up till about 3/4" , then drops to 20. But its a different thread angle to BSF - either 55 or 60 , whichever BSF isn't.

The 1/4" is the same number of threads as BSF, and the two are very easily confused. The BSF nuts more or less go on the CEI bolts and vice versa (only for 1/4" of course), but they strip easily cos the thread flanks aren't in good contact.

Show me a Meridan Triumph, and it'll be 99% certain that the 1/4" CEI threads will have BSF nuts/bolts jammed onto/into them.

So 3/8" CEI is 26 tpi . 60 degree thread form (I just looked it up)

The difference between CEI and BSC is that BSC only had a limited subset of the CEI sizes. Same thread, but CEI had big ones (like the steering stem ). BSC was just the small ones. Spanner sizes are the same a BSW/BSF

Used to be lots of good threads. BSW BSF BA UNC UNF SAE BSB BSG BSP BSTP BSM. Not many people know what BSM was (may still be for all I know).

Incidentally am I the only one who gets pissed off when folk on Tardme and such like refer to SAE/UNF/UNC as "imperial". They're not they're US. Imperial is Whitworth, BSxxx. Spanners are different and all .

BA was a funny thread too, it was a metric Imperial thread. True.

[vifferman]

Imperial sux.

Mind you, I discovered years ago that there's metric, and metric.

[Paul in NZ]

BA was a funny thread too, it was a metric Imperial thread. True.

Used on the old pom telephone exchange gear too - quite a coarse thread from memory!

From mid to late 60's the poms started 'unifing' the threads on british bikes but you are right - it can be a nightmare! 'Cycle' threads were not that common though but used in wierd places. I had a mare getting a replacement clutch hub nut for an old AJS once because of the 26 tpi thing. Solved with a nut from the old mans box of bits

[GSVR]

I don't understand how they arrived at 47.5 degrees for the thread angle for BA.

As for all other threads make all mine metric.
Working out the tapping drill size in metric you can do in your head. And as I don't often work with Imperial except BSP I don't have anything commited to memory and have to look it up.

If any thread is closest to metric in imperial measurements it would have to be Unified I reacon.

[Ixion]

Beezers used them a lot. Prolly cos BSA started out making bicycles, so when some eager dude first got the notion of bolting one of them newfangled infernal combustifcation thingies into one, he just grabbed a handful of nuts and bolts from the cycle assembly line. And then each time they refined the design of the new (Wotcha gonna kawl hit, Bill . Wodda abart a muddabark, eh) muddabark, they just grabbed another handful. So pretty soon, Brits being Brits, it was sort of a cast iron law of the universe that they HAD to use cycle bolts and nuts. Quite a good thread actually , except for the confusion of it all.