THE SUMMERLANDS CHUFFER

Accucraft 4-4-0

Larry Green in the US has fitted a Chuffer to his Accucraft 4-4-0 which is supplied with two different types of stack. The diamond stack (on Col. Boone) should work fine as the chuffer is inside the tube at the base of the stack. The full balloon stack (the Rushton?) requires a tube to be fitted inside to give the resonance.
Here are Larry's notes from MyLargeScale.com and Llyn Rice's photos:

"With the temp here at 39 degrees and no sun, I steamed the 4-4-0 outside with a load today. The first run was disappointing, with some increase in volume, but no sharp beat like with my 2-6-2. The 4-4-0 has a hollow tapered stack (Rushton?), so I figured the sound was being lost as exhaust swirled around inside before exiting.

After taking measurements of the inside base of the stack, a 2 7/8" long piece of 1/2" OD X 7/16" ID brass tubing, pressed into a .785 dia. bushing with a milled notch to clear a stack assembly screw, was dropped in place. With another test run,that modifiction produced the nice exhaust beat and volume from the Chuffer.

When checking another similar stack from Accucraft, I found the internal design at the base to be quite different from the one installed on my engine, so the sleeve design will have to be determined for each engine.

I'm very satisfied with both installations of the Chuffer on my engines."

 Larry added the following comments in a second post:

"I would expect the inside dimensions at the base of all of these to be different, as found with the two I have. The tubing I used was in my collection of materials, but a suitable tube should be available from K&S Metals at a hobby supplier.

One possible "universal" bushing for the base could be to pour JB Weld high-temp epoxy around the outside of the tube bottom, but this is semi-permanent and might turn off some owners. I can think of some other solutions easier than what I did, but the dimensions for each stack design must be determined first before deciding."

Larry Green's solution - see text. There may be simpler ways of achieving this as Larry suggests.