Roundhouse Atlantic - Part 1
Peter Rohde and Dave Mees fitted the SCGP1 Summerlands Chuffer to the new Roundhouse Atlantic. This is very complex, and not for the faint hearted or inexperienced! Here are Peter's notes:
"The position of the origional chuff should first be measured From the top rim of the chimney to the top of the Roundhouse chuffer on our example measured 20.5mm.
Now turn the locomotive up side down with the smokebox end towards you. Two sets of pipes can be seen which take the live and exhaust steam to the cylinders. The four nuts on the two tee pieces should now be undone. Note that the seal on these connections is made with four "O" rings.
Now remove the screw holding the front buffer inplace and remove buffer from body. This gives access to the four cap screws that hold the two cylinders to the frame two cap screws per side. These four cap
screws need only be slacked off enough to allow the two cylinder blocks to move out enough to touch the outer valance.
On no account remove the cap screws entirely as the cylinder will touch the valance long before they come out of the cylinder block, they are a pig to put back, you have been warned!
Now comes the technically hard bit.
With two strong hand and two good snipe nosed pliers you now need to remove the top Tee piece from the locomotive. This is done by twisting one or both of the top set of pipes so that the Tee is no longer
captivated between the two pipes. This connection is going to be remade so try to be restrained in your violence, there probably is a trick to this process only it's yet to be discovered (see below!).
Once you have the Tee piece and its soldered pipe out of the loco and on the work bench it now remains to work out where you are going to cut it. Our Tee piece had a bit of pipe that looked very second hand attached to it with multiple kinks in it.
After a lot of discussion and debate we removed 32mm from the top of the original exaust pipe on the grounds that we could take it off but not put more on. This resulted in the new chuff pipe distance of 7mm when re-assembled in our case.
The resulting cut down chuff pipe will now have to be rubbed down so that you new Summerland chuffer is a tight push fit over the pipe.
Our Summerlands Chuffer did not have a slot cut in the top, so you will now have to experiment with the resultant chuff pipe down the Atlantic chimney and by reattaching one of the nuts to the tee to give your
self an idea of the position of the new chuff pipe in the chimney. This has to be off set with the chimney such that the cut out in the chuff is not muffled by the chimney wall. It is a good idea to mark the top of the chuff such that the chuff opening can be ascertained when looking down the chimney from the top. When the position of the pipe is to your satisfaction, reattach the second half of the Tee. Check that this has not moved the chuff pipe position so that the opening is not muffled by the chimney wall. Tighten up the nuts on both tee's, making sure that the "O" ring are still in position. The live steam joints should be tightened up more than the exhaust joints and then the four cap screws that hold the cylinders to the frames.
Finally refit the buffer to the front beam.
You can now steam up you loco and listen to the results."
Roundhouse Atlantic - part 2
Neil Simpson in Canada has added the following which makes it sound a little less daunting:
"Thursday night I fitted the chuffer to the Atlantic with ease, and may have discovered the ‘trick’ that Peter Rohde and Dave Mees referred to in paragraph 5 of their notes. I needed no pliers, the fit is perfect and the sound is excellent. I am running in the Atlantic on static bearings, so am able to put drag on the drivers as the engine is running and the increase in sound and note as it slows down is incredible.
I followed the Peter Rohde and David Mees instructions carefully up to paragraph 4 being sure not to undo the cap screws more than necessary which requires a 2mm allen key. It seemed obvious the tee fitting was not going to come out very easily. I removed the two red screws either side of the front buffer – they hold a retainer which keeps the chassis rails in place. With the chassis rails free it was not hard to ease them apart by hand to release the tee fitting. It is best to release the right side first as the exhaust line sits right of the live steam line. The tee fitting slips off the other side and out it comes.
The next bit requires the most amount of thought. There is a lot of bending in the Roundhouse exhaust as it has to negotiate it’s way around the live steam line and up the chimney. The only part that was straight was the top 43 mm. My original pipe measured 19mm from the top of the chimney. I cut 32.5 mm from the top of that pipe leaving only 10 mm of straight pipe to play with, trying to maintain the original curves. I then cut 13 mm off the brass tube on the bottom of the SCGP1 chuffer, cleaning up both cut ends well. It is important to note the original orientation of the tee pipe and it’s copper tube as it will only go in one way. When re-fitting, there is no side to side movement once the tee nuts are started, but there is front to back movement possible. Therefore, orient the chuffer at 90 deg. to the tee fitting with the opening (and slot) facing the front of the engine, and carefully tap it onto the copper pipe.
Since the new pipe with chuffer is fatter than the original, start it in place from the bottom and turn the engine over to ease it up the chimney with a long thin flat-head screwdriver. Once in place insert the left copper pipe into the tee fitting first, then the right, easing the chassis rails apart again. Start and loose fit the nuts on the tees, replace the two red screws either side of the front buffer, then tighten the cap screws to the cylinders, then tighten the nuts on both the tee fittings (in that order). Before the last step, I made a doughnut of pipe cleaner with a 10mm tail and slid it down the chuffer to hold it dead centre as it was tightened. Refit the buffer and remove the pipe cleaner and you are good to go. The chuffer can be tweaked into position as it is following the original curve of the pipe and the copper is fairly soft. My final position was 4mm from the top of the chimney and a little flat black paint made it blend in nicely.
Steam up and listen to the wonderful sound!”