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Steam whistle desigh

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Paul Lousick20/06/2019 13:15:05
1496 forum posts
570 photos

Help required for design of the bottom edge of a steam whistle bell .

Some drawings show a bevel on the outer edge (left drawing) of the bell at the bottom while others show it on the inside (right drawing). While others have a square edge and no bevel.

Where should the gap in the base be located in relation to the leading edge of the bell. Aimed at the inside edge, middle or outer edge ?

What width gap for steam discharge in the whistle base is recommended for a 1 1/2" dia whistle ?



Paul Kemp20/06/2019 21:03:32
548 forum posts
18 photos


I struggled big time to make the whistle that came with the bits for my 4" RP whistle! Read loads of stuff on net which to be honest wasn't very helpful or consistent! Edge of the bell on mine is square and ended up with an annular gap of less than 5 thou. The gap seemed to be the critical bit! Profile of the edge of the bell and vertical height of bell above the base much less important. A decent deep tone depends on size of the bell.


Paul Lousick20/06/2019 23:23:04
1496 forum posts
570 photos

Thanks Paul,

I have also searched the web but could not find a good answer. Looks like it will be a bit of trial and error to achieve a successful design.


Jeff Dayman21/06/2019 00:31:42
1853 forum posts
45 photos

Hi Paul, today I opened my just-arrived copy of a US based magazine " Live Steam and Outdoor Railroading" . They are running a serial of Kozo Hiraoka's Rio Grande K-27 locomotive. This month's instalment is covering Kozo's plans for the whistle and how to tune the gap of it and tune the plumbing and valve to get great sound. If you know someone local to you that gets this mag maybe they can scan these pages and send you PDF. As a general guide / approach to whistle building it is a great article.

If you can't find a copy locally please PM me here.

roy entwistle21/06/2019 08:56:09
1224 forum posts

You will find a difference between running it on air and running it on steam

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