Fixing valve covers to the valve sleeves - help!

[springcrocus]

Gentlemen,

Before I go charging ahead to press the valve sleeves into the cylinders and end up making a pig's ear of things, I would ask how people would secure the valve covers to the ends of the valve sleeves. The drawing shows just a single 4BA tapped hole in the end of the sleeve and, presumably, is designed to take a grub screw or similar with the intention of screwing down onto the front valve cover with a similar arrangement for the rear cover and slide bar assembly.



Now, I appreciate that there is no steam pressure between the valve covers and the piston, it is only exhaust steam, so the ends won't get blown off but this still seems a pretty flimsy way of fixing things.

Although primarily aimed at any Britannia  or Clan builders, it's probably the same throughout the BR standards so any pictures or descriptions on how you built up your own cylinder assemblies would be helpful, even if it's exactly as per this drawing but works OK anyway.

Thanks in advance

Steve

P.S. Spot the deliberate mistake just above the words "BORE HERE TO".

[Roger]

Hi Steve,
I've used three grub screws with their ends turned to a cone point. The valve covers have a similar shaped Vee groove, but it's offset by a small amount nearer the flange so that the grub screws pull the covers back onto the end face. The valve crosshead is supported like that on my design, so that needed to be really secure.
In my opinion it's bad design not to at least provide a flat or shallow groove where the grub screw bears on the surface. It's bound to throw up a burr which will then make it hard to remove the cover.

[Jim]

Hi Steve, I attached the valve end covers with 4 10BA screws. As you say the cover is only subjected to exhaust pressure which the 4 screws can more than handle plus it makes the cover much more easily removed  for setting the valves as shown here. In the end it really boils down to what suits you best.



Jim.

[springcrocus]

Roger, Jim, thank you both for your replies.

Jim, after looking again through your photos, I thought I had seen some screws but hadn't seen the above photo before. In full-size, these screws are present to hold the covers in place so I will copy your way of fixing them, thank you.

Roger, I agree with you and would use three screws myself if I had chosen to fix them that way. Jim's way is more prototypical and the route I shall follow.

No-one else has chosen to comment so I shall assume this thread is now dead.

Steve