Steve,
Ive had afair bit of practise building US 4-4-0s and offer the
following ,
[1] Frames .laser cut in 3/16 steel,, the main problem is the long thin
front portion which carries the cylinders it will finish up about 1/4 inch
deep if you keep scale proportion, but is ok once you bolt up the cylinder
assembly to the boiler and frame..
[2] in 1:20 scale there is plenty of room for a 2 inch boiler inside a
cosmetic shell/casing and because the firebox area is deep and long coal
should be easy, its also ideal for alcohol firing.
[3] Proper stephenson valve gear is fine because therse plenty of space in
front of the main drivers.
[4] Drive wheels are something of a problem now as Locosteam no,longer
exist and we got our castings from them..you want 12 or 13 spoke and around
55 to 60 mm diameter, the segmental balance wieghts can be brass glued on
and filled with epoxy .
[4] we can still cast ,Smokebox fronts, and pilots, and saddles for 1870s
Baldwins in bronze[lost wax].
[5] axle pumps need to under the cab floor, therse no room on the drive
axle.[
[6] Wieght distribution is a problem, the front end is heavy ni models , I
find its best to have the front truck , unsprung on a bearing pad[but with
side control] and just the drivers sprung, this way you can "set" the ride
hieght with the truck and get the adhesion from sprung drivers also a good
ride for youe engineer!.
Maybe we could have a session at Diamonhead in January? over beer of
course.
Gordon Watson.
