5″ Butch -some steaming issues

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5″ Butch -some steaming issues

This topic has 3 replies, 3 voices, and was last updated 30 June 2015 at 00:42 by Ady1.

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11 December 2011 at 20:02 #1058
Ianmac
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@ianmac
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11 December 2011 at 20:02 #79722
Ianmac
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@ianmac
A 5″ Butch was my first steam loco completed mid 2010.

It run well on compressed air and off track steam. First track tests in early 2011 were a disappointment. My club track is a high level 1/4 mile circuit, with gradient.

From initial steam up one got one circuit then one had to stop to allow pressure to rise. This degraded to a half to a third of the circuit till eventually one gave up. Usually some boiler tubes were clogged.

I chased all the usual suggestions, change the grate,use smaller coal ,use anthracite. tweak the blast nozzle, check your valves, etc to no avail. All I was doing was going down culdesacs and wasting a lot of time.

I eventually went back to the theory books and read all the bits I had earlier glossed over, since they contained formula, thinking I wouldn’t need that !

I calculated the the correct throat dia for the Chimney from the actual grate area using two formula . This came to 0.85 ” against the drawing 1.125″.

I turned up an insert for the existing chimney with a throat of 0.8″ and a taper of 4 degree included between throat and chimney top and peticoat radius approximating throat. From the chimney throat position I reset the blast nozzle height, having to make a blast pipe end 1 1/2″ longer than that in the drawing, at the same time I made the blast nozzle detachable and the pipe end was turned to accept a new fixed position blower jet holder with 3 jets rather than the unsupported circle of copper pipe in the original design. Blast nozzle aperture and Blower jet aperture were taken from the tables in Greenly’s Model Steam Loco.

This transformed Butch, steams from startup on blower fan then its own blower takes over at 20 psi . Circuits the track 3 times + without issue and no clogged tubes. Next season I will be trying a lower grade coal.The only major drawing error I found was the running board aperture for the valve chest was too large.

Sorting the above out took some 4 months so hopefully this note may save a prospective Butch builder some time. I keep thinking that perhaps as a beginner I was at fault in trusting the original drawings.?

With anything I look now with steaming problems or start a new build, I run through the above calculations.

Ianmac
29 June 2015 at 17:56 #195359
Peter Jones 14
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@peterjones14
Hi I've got exactly same problem you had is there any way you can give me a sketch of the chimney and petticoat mods and formulas you used and any other useful info
30 June 2015 at 00:42 #195391
Ady1
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@ady1
Well done you. Gives you a boost to get it sorted like that
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