5/16″ by 26tpi – is this a ME thread?

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5/16″ by 26tpi – is this a ME thread?

This topic has 7 replies, 5 voices, and was last updated 27 January 2010 at 19:40 by mgj.

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27 January 2010 at 17:09 #47939
Doddy
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@doddy
Just making a Stuart 10H for my first kit – The plans show the bottom cylinder cover requires 5/16″ by 26tpi thread for the stuffing box gland and nut. Is this an ME thread? I’ve got 5/16″ BSF and M8 fine (1.00pitch) is it worth buying a set of ME taps and dies ? can I make a brass gland follower with two studs (10BA) ?
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27 January 2010 at 17:09 #4937
Doddy
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@doddy
27 January 2010 at 17:30 #47941
Rob Manley
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@robmanley79788
26tpi is a British standard Brass thread written as BSB and gets quite alot of use within the ME world as it is quite a strong thread, often used for safety valves. BSF is 22tpi and therefore coarser than the brass. 8mm fine is 25.4tpi and is very close to BSB in that respect. Personally I would buy the correct tap and die purely because I do not like to mix thread forms and standards on a single model BUT as 8mm is sooooo close, unless anyone came to make a new gland they would never know.

I would buy a set of ME taps and dies to start with, then during the years and exhibitions pick up the BSF, BSW and more BA taps and dies to complete your set.

Be careful when buying a ‘new’ set of ME taps and dies, alot of the new stuff is pretty poor. From personal experience I would avoid using a firm whose name begins with T & T. Rob.
27 January 2010 at 17:41 #47942
Lambton
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@lambton
5/16″ x 26 tpi is a Brass Thread. You could use the M8 fine thread as this has very similar dimensions.

I bought a set of 32 tpi and 40 tpi model engineers taps and dies from Tracy Tools many years ago (when they were in Isleworth) and have never regreted it. They have been worth every penny over the years, I would not bother with second hand ones as you do not know what use or abuse they have had.
27 January 2010 at 18:09 #47945
mgj
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@mgj
You are going to need a set of ME taps and dies simply because most steam fittings are ME series – if steam is to be your thing. They are 55deg whit form, same as 26 TPI brass is.

This is a stuffing gland which just needs to squeeze a bit of ptfe or hemp or some such. 5/16 x32 ME would be fine.

If I might disagree with Rob, I have a set of x26 taps and dies and have NEVER used them. I’ve use ME a lot. However there is a point, which is that, technically if a boiler to a signed off drawing calls for a particular thread such as x26tpi, then really you are obliged to use it, or declare such to the boiler inspector, and he may or may not accept your choice of alternative. In other words the onus is on you to show that the non-conformity is acceptable.

Still, that rigour only applies to “sealed” drawings, and anywhere else on a model you can do as you wish. Nowadays for general purpose use metric is probably best, (though there are applications where space and scale appearance may dictate otherwise.)

Sort of half agreeing with him, my set of ME taps and dies came from T&T! Not brilliant in steel, but OK in brass, and actually brass and gunmetal is where they see most use. So I’m moderately happy there. Their other stuff like reamers and gear cutters have all been fine.
27 January 2010 at 18:40 #47949
Rob Manley
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@robmanley79788
I have to say that im interested in pretty much everything – clocks, vintage cars & motorbikes, kit cars, full size road loco’s, steam and petrol engine models and i get roped into fixing stuff around the house to earn my keep propa. So I do tend to use pretty much every type of thread out there – im still finding situations where I dont have the right tap for the job. T&T are very good for gear cutters, reamers etc but ive waisted money on their taps – I buy J&L now – Lyndon seem to be spot on.

Of course anyone’s advice given here is with respect to their own experience, this is mine
27 January 2010 at 19:10 #47952
martin leslie
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@martinleslie67699
Its horses for courses isn’t it, you accumulate the tools necessary to assist you in doing what you want to do. Like Rob I tend to get involved in loads of different bits and pieces.

My first purchase was a set of Bscy (cycle) thread taps and dies because I’m a nut for restoring old british motorcycles and most of the threads were cycle, which are all 26tpi untill you get up to the large (bigger than 1/2″) sizes.
27 January 2010 at 19:40 #47954
mgj
Participant
@mgj
Well I did say “if steam is to be your thing”. If its Austin 7s then I think Whit might be first on the list!

Edited By meyrick griffith-jones on 27/01/2010 19:41:27
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