by Barry Say » Mon Jul 04, 2011 10:43 pm
Traffic on this list is slo-o-o-ow, so this is a late reply.
C & B must be taken cum grano salis. It is possibly in the words of the white knight - Something of my own invention.
I always presumed that the idea was that there would be an element of gravity closing the valve. With an angled seat the flap wants to fall onto the seat, whereas with a square face the valve could naturally sit a degree or 2 off closed, requiring bag pressure to achieve a seal. I think this argument is specious.
I learnt my pipemaking predominately with Colin Ross who always uses square ends although I can never remember any discussions on this point.
In my opinion, angled ends lead to difficulty of maintenance. It is certainly inconvenient to use a lathe centre on a piece with an angled face, and the valve flap is more difficult to construct.
If I have a set of pipes through my hands which will go out with my guarantee, I have always squared of the blowpipe seat. Of course I would not do this with a set which had historical significance. I have never found any problem with squared ends.
Any further thoughts anyone?
Barry