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Discussion Starter #1
Ran the Mike today, did a little experiment with the chuff pipe to see how it affects stack talk/plumes.
You Tube video here

BIt windy, as you will hear.

First features a modified chuff pipe with a notch cut in it to hopefully let some sound reverberate in the smokebox, pipe extends up out of the smokebox a bit.
Second is just a straight chuff pipe that ends a bit below the top of the smokebox, bit larger in diameter also.
Third is NO chuff pipe, just the nozzle I got from Charles. Best stack talk by far, but no plumes.

I tend to lean towards the first for a good mix. May shorten the pipe a bit to keep the top below the top of the smokebox, may help the 'talk' a little bit more. Any opinions?  Jerry
 

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Jerry,
An effective chuff pipe is one of the things steamers have been experimenting with for a long time with only limited success. At Diamondhead this year, I saw and heard a new design that I think is the most effective. It's a pot belly configuration that replaces the current exhaust pipe. It was installed in a K-27 and is louder than any I’ve heard before. I was told that they are experimenting with two diameters for different size smoke boxes. I was told they are about to make several and release them for sale, so keep your eye out.
 
I too have been experimenting with chuff pipes and after several iterations, I’ve settled on a rectangular one, 3/16 x 5/16 K&S stock. I used a vise to crimp and seal the end, then drilled a #70 hole in it. Its length is so that it goes to the bottom of the smoke box with the crimped top 1 cm below the top of the stack. In my case, the length of the chuff pipe is 12.5 cm. Three cms down the side of the pipe, I filed a slot with sharp edges. The slot is 3 mm deep and 1 cm long. The chuff pipe just slips right over the current exhaust pipe.
 
My rectangular pipe works well at slow speeds and under load, but is not near as loud as the pot belly one I saw at Diamondhead.


 

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Jerry,
When I crimped the end with the vise, there was a rectangular flat place on top. I drilled the small hole there to keep the chuff pipe from flying upward - just enough of a hole to act as a pressure relief.  The steam plume and noise come from the square edged hole in the side. No apparent loss of plume. By the way, my pipe is on a K-27.
Carl
 

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Ive had good sucess with the organ pipe extension. Basically a pipe to slide over the chuff pipe with the arch shaped notch just at the end of the 3mm pipe from the manifold. The 3mm pipe was cut down pretty far say about 1.5" long. I dont have any photos of the thing though. I dont have it installed on my ruby anymore because I changed the stack.
 

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Jerry,
You can see the rectangular hole on the side in the picture. It is 3 cm down from the top and the cut is 1 cm long and 3 mm deep with sharp edges. The # 70 hole is at the top on the crimp.
 

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Jerry
Door #3- allows for each beat to be heard clearly and relief of back pressure for better performance.
 

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The URL for Gordon Watson's design and subsequent discussion is:   http://www.gscalemad.co.uk/forum/index.php?showtopic=8490&hl=chuff+pipe

His design is a basic organ pipe configuration, which has similarities to mine, but is round, is short to hang over the exhaust, and was developed for Roundhouse locomotives. His drawing has been around for some time now and I used it to modify a larger bore pipe for my SR#24 (because it has two exhausts), but Gordon's design did not work on my K-27. I've come to the conclusion that it's a lot of fiddling to find the right combination for a particular locomotive.

Gordon Watson (Argyle Locomotives) Chuff Pipe design
 

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The best results I've ever had were with a straight tube up the stack. This is on an Accucraft Mogul, which was not assembled very carefully. The exhaust nozzle didn't line up wtih the stack and so they didn't screw in the usual 3mm threaded peashooter exhaust pipe. The blast just hit the top of the smokebox and drifted out.

I took a piece of 3/8" brass tubing from my scrap drawer and slid it down the stack so it went over the nozzle and wedged in the stack, ending about halfway up the stack. This engine has the best chuff of any in my roster.

My guess is that the 3/8" tube and the "pot belly" are doing similar things by giving a larger volume to resonate in while keeping the exhaust from mixing with the flue gases and killing the plume.
 

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Discussion Starter #16
Yeah Vance, my second one on the video is just a straight round pipe. First has a notch cut in it , last is just the nozzle that Charles made for me, really gives some awesome sound, reverberating in the smokebox, but NO plumes! These guys are selling a nice 'Cajon' chuff pipe, even have one for the Mike, after the video, look down below and you can hear a Mike with it.

http://www.youtube.com/v/nuUFvKzKqSI&rel=1

You can write Richard here about it: [email protected]

I'm still talking to them, so that's all I know. Jerry
 

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Jerry,
You Tube says the video is no longer available and removed by the user. I told Chris about it and he's gonna check with Richard.
 When it's back, you can find it by putting 'bark box' in You Tube's search engine.
 
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