Boiler Cleading Gap ?

[shmbry]

I am working on a 5" Britannia. How much gap would you leave between the boiler and the cleading ?

[millman]

I would have thought it would be governed by the smokebox diameter, usually the cleading diameter is just a little bit under the smokebox diameter.

[shmbry]

Logical.

[92220]

There is a ring around the end of the smokebox where it joins the boiler clothing. On fullsize it is approx 2" greater than the smokebox radius, so 4" greater diameter. Scale 2" for 5" g is 0.177" (1" = 0.0885" scale). You can work out your clothing outside diameter at the smokebox end, as the smokebox diameter plus 2 x 0.177". That is the theoretical O.D. at the smokebox. Hope that helps.

Bob.
Edit.

I forgot to point out that the Brit and 9F have boiler clothing diameters greater than the smokebox diameter, not smaller.

Bob.

[Jim]

Hopefully this may help.

All the photos of Britannias that I have show the cleading as in the drawing and photo, that is the same diameter as the smoke box and getting larger as it accommodates the coned boiler.

 

Jim

[92220]

That's interesting. Looks like I had an out-of-date drawing!!! I have done some searching and have found only one photo that SEEMS to show a difference in diameters but it is not at all clear. It was, I think, an early photo where a new boiler was to be fitted. All the others I have found show the boiler and smokebox the same diameter where they meet. Just goes to show that careful research is needed when working on a scale model, and it is so easy to get things wrong when relying on memory!!!

Bob.

[Nigel Bennett]

The BR Britannias, according to those nice photographs that Mrs Google has in her album, seem to have identical cleading diameters to smokebox diameter where they join. However, taking a peep at her bulky volume of 9F photos, it shows quite clearly that here, the smokebox diameter is a good bit smaller than the adjacent cleading, which has a nice rounded transition to meet it.