[modeleng] Re: Juliet boiler question

Gents,

Under our miniature copper boiler code, the minimum ligament between tubes 
is 3mm. All plates are measured before assembly by the boiler inspectors. 
LBSC, when he designed the boiler, uses only 1/16 ligaments for most tubes, 
and 93 thou' on the larger spacings. I can probably drop the height a bit, 
by widening the tube spacing. This should present few problems, as there 
seems to be more than enough space in the front tube plate..... and the 
firebox tube plate.

Ok done that, and there is now only 92 thou' extra height to the crown. The 
firebox tubeplate is now the same dimensions as the orriginal, except for 
the extra 92 thou' extra length.

Next question......

Now I know, that those so called superheaters, don't do much more than act 
as dryers (only slightly) and no more. In some ways I would be better of 
without them. Easier tube cleaning etc.... I could replace the 2 superheater 
flues with 4 of 3/8" tubes and have the same heating surface. Infact I could 
have an extra 3 of 3/8" tubes above what would replace the superheater 
flues, if I put in 2 actual rows of flues. The crown would then come down 
lower than the original design, and provide an extra 23% heating surface in 
the tube department.

Can someone please point out reason why I should leave the superheaters in?


Cheers,

Phill.


----- Original Message ----- 
From: "Alan Stepney" <alan@xxxxxxxxxxxxxxxx>
To: <modeleng@xxxxxxxxxxxxx>
Sent: Sunday, May 24, 2009 1:20 AM
Subject: [modeleng] Re: Juliet boiler question


>I wouldnt be happy with 1/4" change (Ok, 0.222" but thats close enough!)
> 1/8" wouldnt concern me, so why not slightly reduce the tube-to-tube 
> spacing
> so that you only alter the crown height be !/8" or less.
> That boiler steams well, so the difference shouldnt affect it.
>
> All the other items you mention can be fitted in, and as long as the 
> bottom
> nut on the guage glass is well over the crown sheet, there should be no
> problem.
>
> Alan
>
>
> ----- Original Message ----- 
> From: "Phill Smith" <steam@xxxxxxxxxxxxxxxxxxxxxx>
> To: <modeleng@xxxxxxxxxxxxx>
> Sent: Saturday, May 23, 2009 4:10 PM
> Subject: [modeleng] Re: Juliet boiler question
>
>
> G'Day Gents,
>
> Sorry to bother you all with my questions. Again.....
>
> I have just been going through the boiler design as per the book, and
> redrawing it to meet our boiler code. To fit the tubes into the boiler 
> with
> the correct size ligaments between the tubes, (and keeping the same number
> and sizes of tubes) I found that the crown plate will rise 222 thou'. Can
> anyone see any problems with this happening?
>
> The problems I can see are as follows;
>
> Bottom cock on water gauge lifting same amount and hence reducing gauge
> glass length.
> Less safety margin for beginners to play with in the water level.
> Distance between longitudal stays and firetubes reduced. (though they can 
> be
> moved a bit as well, maybe)
>
> Anyone else see any other problems? (Especially you Alan, as you have 
> built
> one!!!!)
>
> Cheers,
>
> Phill.
>
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