James Wilkinson Sword wrote:

On Wed, 15 Mar 2017 16:42:42 -0000, harry wrote:

On Wednesday, 15 March 2017 13:03:46 UTC, James Wilkinson Sword wrote:
On Wed, 15 Mar 2017 01:18:10 -0000, Roger Hayter
wrote:

James Wilkinson Sword wrote:

On Tue, 14 Mar 2017 20:10:11 -0000, Roger Hayter
wrote: snip The calipers said 14mm, reading the outer diameter of
the thread of what used to be in it. BTW, your adapter is M to
F increasing, is it? M to F reducing is commoner and won't help
you! Yes, I selected the female and male sizes seperately from
drop down boxes.

Should all work then! Copious PTFE tape should work for the taper
one, the other may need tape, fibre washer *and* sealant if both
threads are parallel.

I know about PTFE tape, but there is something else I can do if the
male is 14mm and the female is 15mm?

Pipe threads are taper cut,

I've never noticed that. Must be a very gradual taper.

Sealant on the thread is squeezed out as the pipe is screed into the
fitting.

Larger pipes are cut with adjustable dies so whatever thread size deemed
appropiate can be cut.

Traditionally "Boss White" and hemp was used with water/steam. And"Stag"
with petrol/oil.

So what do you suggest I do with a thread that's 1mm too small?

If they screw up tight but feel a bit sloppy before tightening then you
need sealant. If they won't screw tight at all then most likely they
are different thread families. If they just fit inside without
touching then the female thread must be 3/8" BSP and not 1/4".

--

Roger Hayter