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This thread relates to anyone with Accucraft Rubys equipped with balloon stacks still having problems with the burner flame going out when ever the smokebox door is totally closed. In our small group of Steamaholics, we have four Rubys, two with straight stacks and two with balloon stacks. Both the balloon stack equipped locos had been experiencing this burner flame-out problem. The burner appeared to be affected by back-pressure whenever the smoke box door was fully closed. In an attempt to correct the problem, I removed the balloon stack and drilled it out with a 5/16 inch drill using my small lathe. After trying the stack on the loco, without success, I drilled the stack out with a slightly larger (11/32 inch) drill. After again trying the stack on the loco, the burner problem was improved but not solved. I was a bit worried about thinning the stack tube too much, but decided to try one more time with a 3/8 inch drill. This time the burner worked fine with the smokebox door fully closed, and the stack did not appear to be weakened in any way. Now both of our Rubys equipped with balloon stacks have been drilled out to 3/8 inch diameter, and the burners work fine. This "fix" seems to have solved the problem.


emartin187,  SA 360,  Thunder Valley Narrow Gauge


 
 

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emartin187 - question - are the straight stack Rubys also at 3/8" diameter?
or are they built with a different smokebox configuration?
 

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Discussion Starter · #3 ·
The Ruby straight stack inside diameter is about 5/16 inches althought I would have to take one apart to measure it.  I am not sure why the difference between the two stacks, but it may have to do with the longer path of the gases creating a higher back pressure with the balloon stack.

emartin187,  SA 360,  Thunder Valley Narrow Gauge RR.
 

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Sounds like a worthwhile mod.  My Ruby has now gone through most of the burner mods - today I ran with mesh covering the burner, and it definitely helped.  I did notice water (and oil?) bubbling out of the 'chuff' pipe, which reaches to the bottom of the balloon portion while running, and the amount of stuff in the smokebox seems to affect the burner draft.  It may also be realted to the smaller holes in the bottom of the smokebox - see Dave H's old post in the archives.

 

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This was also the problem with the Fort Wilderness locos discussed at length initially. The real issue is that the bottom of the smokebox needs to be openned up to open onto the track..its too enclosed. The steam oil in the smokebox pops and causes back pressure which blows out the burner. Since I didn't want to disassenble the loco to change the saddle, all I did with mine was trim off the top of the copper blast pipe, so that the steam oil would shoot up right out of the stack and not flow back into the smokebox. Gordon put the mesh on the burner too. I run the first lap with the smokebox door open just to allow the loco to clear the cylinders, then close it for the rest of the 20min run. I've run it this way for a couple of years now with no more problems. I usually let her haul two of the FW coaches. I should try her out with the 3rd car sometime!

No more mods are needed on my loco, she's reliable and a good runner now.

David.
 

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You can also increase draft (suction) by running a brass tubing sleeve over the copper exhaust pipe, extending the sleeve up to the top of the balloon. A balloon will slow the velocity of the hot gasses exiting the stack (that was it's purpose in real life - by slowing the velocity, it allowed embers to collect in the stack, rather than shoot out to start trackside fires). I also clip off the crimp on the end of the copper pipe; this shoots more of the condensate and oil out the stack, albeit at the risk of getting a facefull when the loco starts up. However, the removal of the crimp also helps eject priming water (if I happened to over-pump when refilling the boiler thru the Goodall valve); if the priming water is allowed to flow into the smokebox, it will tend to snuff the fire. My friend Phil Crowell added a balloon stack to my Mogul. The hole in the stack is very small, so I sleeved the copper pipe and got good results. I experimented, and found that I did not have to run the tubing sleeve all the way up - ending the tubing below the rim of the stack allows the chuff to reverberate w/in the stack, making for a distinctive sound as the Mogul runs.

W/o a big hole in the bottom of the smokebox, as explained by David above, the gasses may not exit the smokebox quick enough to vent the CO2, etc., thus snuffing the fire. You can open up the drainhole on the bottom of the smokebox, or sleeve the copper exhaust pipe to bring the gasses to the top of the stack, or simply drill out the stack itself, as Emartin suggests.
 

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Posted By David Fletcher on 01/19/2008 3:30 PM
This was also the problem with the Fort Wilderness locos discussed at length initially. The real issue is that the bottom of the smokebox needs to be openned up to open onto the track..its too enclosed. The steam oil in the smokebox pops and causes back pressure which blows out the burner. Since I didn't want to disassenble the loco to change the saddle, all I did with mine was trim off the top of the copper blast pipe, so that the steam oil would shoot up right out of the stack and not flow back into the smokebox. Gordon put the mesh on the burner too. I run the first lap with the smokebox door open just to allow the loco to clear the cylinders, then close it for the rest of the 20min run. I've run it this way for a couple of years now with no more problems. I usually let her haul two of the FW coaches. I should try her out with the 3rd car sometime!

No more mods are needed on my loco, she's reliable and a good runner now.

David.

Here's a photo of the FWRR/Ruby stack orifice - it's 1/4" and that 'chuff' pipe takes up most of the space.  I noted lots of big globules of oil/water being ejected - and those tend to restrict the amount of hot air that can exit from the burner.  The stack (see photo above ) seems similar to the "Ada" version, which is where this thread started.

I concur with Dave that cutting bigger holes in the bottom of the smokebox sounds like a step in the right direction, but I'm reluctant to start tearing the loco down - my experiences with Accucraft's tiny screws is that the threads tend to strip or the heads get corrupted easily. Not to mention the mess I'd make of the paint job.

Ejecting oil & water from an un-crimped pipe will also make a mess, but that may be preferable.  Charles and I were discussing extending the crimped chuff pipe so that ejected crud runs down the side of the stack, not down the pipe and into the flame.  One could bend the chuff pipe slightly to make it favor one side or the other away from the heat.  Might cut down on the big kaboom of oil burning up at the same time.

 
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