1/4 " odd thread

[morrisman]

hi

I am making the dial indicator accessories set as in Harold HAlls Workshop projects book.

He says to use this thread on the clamping bolt: 1/4" X 40 ME

Is this a peculiar thread for dial metrology accessories ?

Mike

[Michael G]

Not that I've heard of (although that does not mean much). There are constant pitch series of threads - I think the 26tpi series are called bicycle threads (because they were common on ________). The 40tpi series are called Model engineer threads, presumably because they were common in model engineering.
Can't help with a 1/4 by 40tpi but do have a 5/16 by 40tpi tap and die if that is any use. Other than that if it is just for a clamp any fine pitch thread will probably do.

Michael

[morrisman]

Not that I've heard of (although that does not mean much). There are constant pitch series of threads - I think the 26tpi series are called bicycle threads (because they were common on ________). The 40tpi series are called Model engineer threads, presumably because they were common in model engineering.
Can't help with a 1/4 by 40tpi but do have a 5/16 by 40tpi tap and die if that is any use. Other than that if it is just for a clamp any fine pitch thread will probably do.

Michael

Thank you

I was not sure what the "ME" stood for . Model engineer of course

Mike

[jhovel]

Here is an idea: since there are a few 'odd' threads we only use 'once in a lifetime', perhaps we could have a thread where we can register our unusual threading tools.
I've loaned out an apparently non-existent M4x.75mm tap and die on one occasion and have a few unusual thread siizes in either tap or die or both.
I have a 1/2"x40TPi (ME) tap and die, as well as both M7x1 and M9x1.25 taps and dies.
I'd be happy to loan any of these for one or two off threads to members.
For some loan rules, I propose that if you need to make -say- five or more threads in any of the sizes for loan, you need to find and buy your own.

What do others think about such a scheme?

[Toggy]

Hi Joe,

those small taps are scary to use. I would much prefer to find my own or use something alternative like metric fine. It is annoying enough to snap your own; but somebody elses in an unobtainium size?

Ken

[pipeclay]

Such a plan would have merit.

Not sure how you could be sure as to how many times a particular tool would be used.

Arrangements would need to be in place for forward and return postage,as well as suitable packaging.

A deposit system would also need to be in place,preferably held by a 3rd party.

Rules governing amount of deposit would have to be worked out,possibly based on ease of replacement.

I would think that items of a particular type or rarity would require a deposit of new replacement cost.

You would probably have to supply a detailed description of how you want the tool used.

[RayG]

Here you go.

M E 1 4 X 40 TPI TAP SET INC Taper Intermaite Plug | eBay


Ray

[Uncle Al]

Not that I've heard of (although that does not mean much). There are constant pitch series of threads - I think the 26tpi series are called bicycle threads (because they were common on ________).

26tpi threads are referred to as "brass threads" for some reason, and were common in electrical fittings, particularly in lighting assemblies. The thread on switched sockets as used in reading lamps is 5/16" or 3/8"x 26tpi, and sometimes used on ceiling sweep fans when they have an inbuilt light.

The following link has a short explanation - British Standard Brass Thread

Hope this is of interest.

Alan...

[jhovel]

Here you go.

M E 1 4 X 40 TPI TAP SET INC Taper Intermaite Plug | eBay


Ray

That is a very reasonable price - especially from LPR.

40TPI gives you an advance of 25 thou per revolution - a good pitch to make 250 division dials for 1/10 (0.0001") feed per division. I suspect that's why Harold Hall used that fine thread.
An alternative would be the common 20TPI 1/4" threads (W and UNC) for 50 thou feed per turn - a 250 division dial would then of course give you 2/10th....

[texx]

there are a few aussie suppliers that sell that stuff here is a link to one of them .

Taps and Dies

[franco]

26tpi threads are referred to as "brass threads" for some reason, and were common in electrical fittings, particularly in lighting assemblies. The thread on switched sockets as used in reading lamps is 5/16" or 3/8"x 26tpi, and sometimes used on ceiling sweep fans when they have an inbuilt light.

The following link has a short explanation - British Standard Brass Thread

Hope this is of interest.

Alan...

Alan,

The 26 TPI Brass (BSB) thread and the 26TPI Cycle (BSC) thread mentioned by Michael G are two different animals. The brass thread is of Whitworth form, with a 55 degree thread angle, and - heaven knows why these two British thread systems should have been developed and in use at the same time - the cycle thread uses a 60 degree thread angle, and a thread form similar to the ISO metric one. Maybe two different trades protecting their own territories?

FWIW 1/4 BSB and 1/4 BSF threads are identical, so the same taps and dies can be used for both these threads.

Regards,

Frank.

[Oldneweng]

26tpi threads are referred to as "brass threads" for some reason, and were common in electrical fittings, particularly in lighting assemblies. The thread on switched sockets as used in reading lamps is 5/16" or 3/8"x 26tpi, and sometimes used on ceiling sweep fans when they have an inbuilt light.

The following link has a short explanation - British Standard Brass Thread

Hope this is of interest.

Alan...

I replaced the switched sockets on our bedside lamps a year or 2 ago. Old size was 3/8 x 26tpi (I guess). New size was 10mm x 1mm pitch. All came from the light shop my step daughter works for. Tube was ordered by her in a 1 m length. It was threaded all along. Just cut to size. I had to order some nuts from UK so I got a few while I was at it. It all became quite an exercise in frustration, but the lamps were treasured by SWMBO. Marble and brass castings and she made the shades.

Dean

[cba_melbourne]

Thank you

I was not sure what the "ME" stood for . Model engineer of course

Mike

Harold Hall probably used an ME thread, because he would have assumed that everyone reading his books would also be a model engineer and hence automatically stock ME taps.

As it is, I believe these ME taps are mainly popular in the UK. I at least did covert all ME threads into common metric threads when building my first Stuart steam engine, simply because I had Metric taps and did not want to order special ME taps and dies from the UK. which would then only be of exlusive use for homemade bolts and homemade nuts used in scale looking homemade steam engines and nothing else. Also I only had metric lathes to begin with, that could not cut proper imperial pitches.

If I was you, I would substitute a common metric thread for that indicator clamp. Chris

[Uncle Al]

The 26 TPI Brass (BSB) thread and the 26TPI Cycle (BSC) thread mentioned by Michael G are two different animals. The brass thread is of Whitworth form, with a 55 degree thread angle, and - heaven knows why these two British thread systems should have been developed and in use at the same time - the cycle thread uses a 60 degree thread angle, and a thread form similar to the ISO metric one. Maybe two different trades protecting their own territories?

FWIW 1/4 BSB and 1/4 BSF threads are identical, so the same taps and dies can be used for both these threads.

Regards,

Frank.

Wouldn't life be so much easier if there was only one standard for threads, be it metric, UNC & UNF etc. All this mucking around with 55 degree and 60 degree angles, UNC and BSW almost the same (55 Vs 60 degree) except for 1/2" (12 tp1 and 13tpi) can drive a bloke nuts.

Alan...

[fxst]

easy to do if you don't do model engineering but even then there are metric threads that can be substituted for most modelling. I use mainly BA or metric and I believe BA is 60degree thread like metric, unc and unf. I buy the odd one to replace in my old sets when they get blunt.
Pete