ME nuts and bolts

[Peter Simpson 2Participant @petersimpson2]

Just about completed the hornblocks and axle boxes on my 5″ gauge “Speedy” . The original plans call for several threades in ME sizes, ie 1/4″x 40, 5/32″ x 40. etc

As I cannot find a supplier of fixings in ME sizes what is the best solution.

1, Convert to the nearest BA size.

2. Purchase Hex bar and fabricate all of the fixings to ME sizes.

 

Peter

 

[Peter Simpson 2Participant @petersimpson2]

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi PS2 ,

 

I’m not quite understanding your enquiry . Nuts and bolts in ME thread sizes have almost never been available from suppliers and were very rarely called for on drawings .

 

For pins and various made parts taps and dies are readily available in ME sizes .

 

For common fixings BA is certainly adequate and in most drawings pre metrication was almost always used . BA nuts and bolts are still readily available .

 

MW

 

 

[JasonBModerator @jasonb]

I’d change all the fixings to BA and keep the ME for steam fittings, boiler bushes etc.

 

There are a few ME nuts available off the shelf but not a vast range, the only ones I can think of are from Steam Fittings and intended for use on fittings like back nuts on bulkhead fittings not as general fixings.

 

If you want you could make all the fixings but life is too short, having said that I’ve just made all the nuts, bolts and screws for an engine as they were non standard head sizes and there were only a couple of dozen total to make in various sizes.

 

J

[DAVID POWELL 4Participant @davidpowell4]

Peter,

 

I understand your question perfectly and one might wonder why these threads were invented. Guess they have lots of threads per inch for better fixing?

 

As far as I know nuts and bolts in ME threads has never been available commercialy.

So you can if you wish spend a great deal of time generating expensive swarf

 

Pesonaly I use BA for the smaller sizes and metric for the larger. 6mm is about the same as 0BA. BUT Jason has a point with steam fittings. If you buy them they come with ME threads, so you will have to buy at least one ME tap to fix them to the boiler.

 

Hope this helps

 

 

 

 

 

 

[Ian S CParticipant @iansc]

The model engineering thread is an extra fine Whitworth, the American version is a extra fine version of UNF, UNEF, these threads are used for fine adjustments. The ME thread has been adopted by model engineers, and is less used in industry, there proberbly is a metric one to, I know that in the larger sizes there is the .75 mm pitch series of threads.   Did BA take ove from EF Whitworth?     Ian S C

Edited By Ian S C on 13/02/2012 00:59:35

[David LittlewoodParticipant @davidlittlewood51847]

The 0 BA thread is exactly 6 mm x 1.0 mm pitch. It does though have a different thread form from ISO metric (47.5 degrees thread angle and 60 degrees respectively, and a few detail differences in shape).

 

ME threads have the advantage that they are easy to screwcut with a lathe with an imperial (or dual) gearbox. BA threads are a total pain in this respect, almost all of them have pitches which are not round numbers, each one being 90% of the one before it.

 

David

[Richard ParsonsParticipant @richardparsons61721]

Peter The origins of M.E. threads are a bit of a mystery. There are TWO variants available today these are the 40 TPI and the 32 TPI. Both are in the Whitworth thread form.

They were designed for simplicity of manufacture and for use in thin materials. Most model engineer’s lathes of the pre-war period had 8TPI lead screws. With a 40 or a 32 TPI threads you can ‘drop in’ anywhere. There may have been a coarser thread of 24 TPI but it may have been lost. For ME size bolts from ¼” up I use BSF (as I have the taps and dies). Foe smaller than ¼” (6mm downwards I tend to use the now illegal BAs.

The third set of threads, called ME are the 26 TPI threads. These are the ‘Brass’ or ‘Birmingham Brass’ threads. These are used on most boiler fittings. The 26TPI ‘Birmingham Brass’, which are again in the Whitworth thread form, should not be confused with the old 26TPI Standard Bicycle threads which have a different thread form. I will not go into them here, except to say that taps and dies of this series are marked with a letter ‘C’.

Finally The BA series threads which were introduced at the turn of the last centenary. Here the sizes run from the largest ‘0’ BA down to ‘24’ BA. They are said by the authorities to be inch standard and therefore forbidden in The EU. BA threads are not inch standard. The starting size ‘0’Ba is 6mm with a 1mm pitch with a 47.5° angle. The smaller sizes have a pitch which is 90% of the size larger so, 1BA has a pitch of 0.9mm, 2BA 0.89mm and so on down to 25 BA which has bar diameter of 0.25mm. If you want more look here.

Do not let your local authority know you have BA sizes they will do their nuts according to them (even now) all Non metric threads are illegal!! You try to tell them that and unless you have several £1000 to throw away they will throw the book at you.

[Richard ParsonsParticipant @richardparsons61721]

Aaaag!! Made an error 2 BA has a pitch of 0.81mm NOT 0.89mm

Rdgs

Dick

 

[JasonBModerator @jasonb]

Don’y agree with your last paragraph, plenty of companies selling Imperial fixings and taps & dies non of who are breaking the law.

 

Imperial (BSP) is still the industry standard on plumbing fittings, thousands used each day.

 

J

[KWILParticipant @kwil]

BSP is a world standard, even if it has been given metric dimensions. I do not know of any UK local authority that would even know what a BA thread is.

[Terry LaneParticipant @terrylane]

Begs the question, dunnit! Just how do you make an imperial thread illegal? Around 30 odd years since we ‘went metric’ here and the whitworth bolt is still the hardware store standard.

[Ian S CParticipant @iansc]

Whitworth, and BSF are getting more difficult, as are UNC/UNF, general hardwear stores have mainly metric. Ian S C

[Peter Simpson 2Participant @petersimpson2]

Hi Guy’s

Thanks for the feedback, I have decided to change the ME threads to BA. As for the statement by Michael Williams that “ME threads were very rarely called for” This is my fiirst attempt at a Loco. The Drawings of “Speedy” are littered with fixings with ME threads!

 

Peter

[DMBParticipant @dmb]

Hi all,

Nobody mentioned ME60t. Some years ago it was possible to buy sets of 32/40/60tpi ME taps `n` dies. Not seen 60 for sometime now, though. Just thought I would mention it as reading preceding posts, it reads like only 32/40 ever existed.

John

[JasonBModerator @jasonb]

Tracy tools will still sell you 60tpi taps & dies.

 

J

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