A Summerlands Chuffer has now been successfully fitted to a 1:29 scale Aristocraft Mikado by Jerry Barnes. The following notes are based on Jerry's trials and numerous emails. All the photos are also supplied by Jerry.
Although the Mike has a plastic smoke-box and stack, there is a fixed metal inner smoke-box and a removable metal liner inside the plastic stack. This stack tube has sufficient internal diameter (9.9mm) for most small locos, but the Mike has a big boiler and a lot of hot flue gas to clear. Initial trials showed that the burners would not light with a Chuffer inside the stack - so Jerry removed this metal tube and fabricated
a new one from K&S tubing.
Fitting the Chuffer
The stock exhaust pipe looks like this:
To remove it Jerry suggests using a peice of 8mm OD K&S brass tube with a small 1/4" slit in the end and spread apart a little to be an improvised wrench. See top of photo below top left. An alternative would be to use a larger tube, but with the end flattened a bit to grip the nut.
The correct Chuffer is the SCGP2 (a general purpose one which fits a number of different locos) which has a 48mm chuffer and a 25mm brass tube fitted that will be a firm push fit on the cut down stock exhaust. The total length of the fitted Chuffer and exhaust needs to be 83mm and I would suggest that you initially cut 30mm from the crimped end of the exhaust and clean up the cut end with a file. Test how firm it is to push fit - remember that any distortion or bending in the tube will make it very tight.
Now adjust the length by trimming either the exhaust or the Chuffer adapter tube to get the correct length.
The Stack Tube
Two versions of the Aristocraft stack tube are shown on the right. In replacing the tube, the aim is to achieve approx 12mm internal diameter and Jerry achieved this using K&S brass tube. He found it necessary to turn 0.15mm from one end to make it fit and then added a brass ring to prevent it dropping down. Jerry had pointed out that the need for turning down the diameter can be avoided by opening out the hole in the stack just a little with a Dremel or similar (or you could use emery glued to a piece of dowel). Jerry says that it is easy to do - but take great care - just a very little needs to come out! The piece of tubing round the outside stops it dropping in.
Here is the pipe in position: