Just use same dimensions for everything except the packing groove. Allow
about 10 thou for the ring to roll in the groove (doubles the life of the o
ring!), and make the depth of the groove a few thou less than the ring dia,
usually 70 thou. There are tables for fitting o rings, the old Reeves book
did have the tables at the back. If you remind me the pump ram dia, I will
check the sizes for you.
Simon
ps, Ted B wont be happy, he hates o rings! I think they make model steamers
worth building.

----- Original Message -----
From: david_steam <no_reply@...>
To: <halfinchlivesteamforum@...>
Sent: Monday, July 21, 2003 10:02 PM
Subject: [Half inch live steam forum] USA Austerity


> I am making a loco pump for my USA austerity loco, looking at the
> drawings it is the same as Austere Ada (amongst others I guess).
> My question is, if I wish to use O rings as opposed to loose packing,
> where can I find a suitable drawing and dimensions for the ram and
> body size?