[modeleng] Re: Balls - what sort do you have and how do you seat them comfortably?

Welcome aboard Phill & Chas - good to see youse made it.


> Definately use the "light tap" with the brass rod and stainless ball.
> Something to note though, and that is that you need to hit it very
squarely
> onto the seat. To do this use a rod that is a neat sliding fit into the
body
> of the safety, as then the body will act as the guide to keep the rod
> central. Oh, one other thing, put a sall centre in the brass rod and drill
a
> shallow hole 0.7071 times the diameter of the ball in the end. This will
> ensure that you don't bruise the ball, as the contact angle is 45°.
>
> Lapping the seat is not a recomended proceedure, as it rarely gives you an
> even land width all the way around the seat which is the major cause of
> leakage later on, and, it doesn't preharden the seat for you.
>
>
> ----- Original Message -----
> From: "Allen Messer" <al_messer@xxxxxxxxx>
> To: <modeleng@xxxxxxxxxxxxx>
> Sent: Monday, September 27, 2004 10:57 PM
> Subject: [modeleng] Re: Balls - what sort do you have and how do you seat
> them comfortably?
>
>
> > Ye had me worried for 'alf a mo' there, Laddie!
> >
> > I have always used the traditional method--a SS ball a
> > short piece of Brass rod and a tap with a hammer, but
> > you may want to inspect the seat with a strong
> > magnifying glass to make sure there is not a little
> > burr or defect in the seat first.  If there is, your
> > idea of polishing/burnishing may be the best bet.
> >
> > Al Messer
> > --- Peter Sheppard <peter.sheppard@xxxxxxxxxx> wrote:
> >
> > > No it's not a porn site!
> > >
> > >
> > > I have recently been running the Hunslet on air
> > > (albeit briefly as even
> > > with a 50 litre tank it gets through the air at a
> > > phenomenal rate!)
> > >
> > > One thing I have noticed is that one of the safety
> > > valves starts to weep at
> > > around 30 psi, the other has a far sharper opening
> > > at 90psi (the loco is 90
> > > psi working pressure).
> > >
> > > I have inspected the safety valve and it is a
> > > "standard" bronze ball on a
> > > flat seat arrangement (with a spring to give the
> > > pressure on the seat.)  It
> > > is not a Ross Pop type, but a simple "standard"
> > > safety valve.
> > >
> > > Obviously I would like it to seat better, so I have
> > > a number of questions
> > > for the esteemed membership of the list!
> > >
> > > 1. What is better - bronze or stainless balls
> > > 2. Should I reseat by the traditional method of
> > > stainless steel ball, a rod
> > > and a sharp tap; or
> > > 3. Should I lap a ball into the seat (I silver
> > > solder a ball to the end of
> > > a piece of rod and "burnish the seat) - I don't
> > > usually use any form of
> > > paste, just pressure.
> > >
> > > The seat is about 50mm down in the depths of the
> > > safety valve, the only
> > > access is from the top (you can't separate the seat
> > > from the chamber).
> > >
> > > Any thoughts, any personal preferences?
> > >
> > > Cheers
> > >
> > > Peter
> > >
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