I need an education outwith metric training , i've had so far

[Hopefuldave]

the implication is here
The inside diameter has nothing to do with the thread and the thread is not needed in flow calculations, so naming the pipe thread via internal diameter is stupid

It's not the thread it describes, it's the *fitting* for e.g. 1/2" British Standard pipe. The thread sizes are completely different, if I remember right I had to use a 29/64th as a tap drill for a 1/4 BSP *fitting*

Example, to feed some cables through my lathe's casting I used 1/4 BSP *fittings*, which I had to open up a touch (the inner stop ring to prevent the pipe passing through) so I could put a 10mm diameter TUBE (not pipe, which would have been larger OD) thought the fitting to carry the wires.

The BSP threads were conceived because although pipes themselves were standardised (and could be ordered by internal diameter), the fittings used on them weren't - so different manufacturers' fittings for e.g. a 1/2" (internal) pipe wouldn't mate. Hence it's a British Standard Pipe thread and everybody's fittings er... fit.

Interestingly, a close examination of European pipe threads reveals that they're pretty much direct translations from inch to metric sizes, with Very Odd thread pitches and diameters - almost as though the BSI got it right

Dave H. (the other one)

[Alistair Hosie]

Arcane sorry I am a woodworker first the big shop I have is to do with wood, and the smaller shop has to do with metal , so I am not there in the metal workshop every day. Anyway this is the first inkling that a half inch is not 12.5mm it is frankly not the most clever way of doing things you might as well argue an arm is a leg. IN short 12.5mm should be a half inch not three quarter and it is my first time dealing with this sorry you need to chill what I do and have done over fifteen years is good for me and I continue to learn as I need to and am happy to continue in that vain .It seems to be have a go at Alistair week ,so bring it on get it off your chests all of you..Jakko is a good guy in my book also Alistair

[boslab]

From memory there are more strange things going on with wood, board feet, 1/4 is 3", cords and stands, the early Druids were keen woodworkers at a guess, pipes have always been peculiar but there we go, metalworkers concern themselves with the outside and plumbers the inside, bound to get confusing I suppose.
I must admit I was confused when handed a 1/4 BSP tap the first time, I could see the engraving in them days, I was convinced someone was taking the piss.
Mark

[MattiJ]

Gauges are another fancy "unit" of measure. Steel sheet metal gauge is different from aluminum sheet, drill gauge is not same as copper wire gauge or silver wire gauge or hypodermic needle gauge. Or shotgun gauge for that matter.

[Alistair Hosie]

Boslab and other guys. If you get used to using metric from the beginning, then even with wood, life is what it is! I think metric is better all round but then I am not in your shoes and understand that others have been brought up with different methods actually I was brought up with non metric all inches etc. Change came about and I simply went as most did with it . If you wish to be humorous I could remind you all when we struggled on with non metric pounds shillings and pence 240 of them pennies per pound you guys started off showing us the simplicity of cents to the dollar 100 easy peasy. So think about that guys in the meantime old Al loves you all. Alistair

[Paul Alciatore]

Well, you may not like it. I may not like it. But the ID is the way that PIPE diameter is described. And it is not an exact number as the various weights of a given size of pipe will have different IDs. Confusing? Well, yes it is.

But it is the way that pipe and pipe fittings are described. And you and I are stuck with it.

All of this came about many years ago when pipes were a newer idea. I suspect that everyone who was even remotely involved in the process of standardizing the sizes are long dead. So there is on one to really complain to. We are stuck with it. Learn to live with it.

If you want to nominate yourself for the post of King of the World and if you are willing to add No Cracks in the Sidewalks to your official platform along with a sensible re-do of pipe sizes, then you will have my vote. Good luck!

[Magicniner]

Refer to a chart - I always do the first time I cut a thread I haven't used before, there's lots of trite sayings about assumption, unfortunately many are right

[cameron]

Alistair, thanks for pointing out that there are 240 pennies to a pound. I thought I had the lsd thing all sussed out, but never realized just how simple it is.

And if there are 240 p per pound, it's only common sense that there should 120 pounds to a hundredweight, right?

[Alistair Hosie]

Exactly Cameron right again as usual 20 times a shilling which was twelve pence. Please tell me now now what's that got to do with a pound of feathers? Apart from understanding the answer to this question

is a pound of feathers lighter than a pound of lead? and according to your excellent math I.E. ( if there are 240 pennies per pound, it's only common sense that there should 120 pounds to a hundredweight)

so does that make a half hundred weight ten shillings, or half a quid ,or five packs, of twenty cigarettes, now currently near ten pounds or quid a packet of twenty . I know that and yet I don't smoke, unless I work too quickly.
ten shillings was one sixth of an adults daily wages of around three pounds per day, of twelve to fifteen pounds for five and a half days. Now that was back in 1966 when I left school . Then if you earned twenty pounds per week you were well off. My pal worked here for a day had his dinner and went home charged me £200.00 for one day and that was with no materials used so things have changed. Alistair

[Alistair Hosie]

Exactly correct Paul I understand you perfectly the problem was I understand you but did not understand pipe sizes. As for being KING NO thanks I have no time for Royalty but I am being a good boy for my old pal George who is and deserves rest rest and more rest, so no more on that other than to say I and my feelings are in good and numerous company. LOL Alistair