Here are a few more pictures of Frog and also the "back of an envelope" drawings I used when builiding Frog. A number of people have asked about the bolier and there is a reasonable drawing showing the boiler construction.
Photos:- Click on the thumbnails for a bigger picture.
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Drawings are jpg files. Click the links below:-
Whistke and blower valve sketch
The boiler drawing shows a vertical tube through the bottom of the firebox. I put this in so I could try meths firing if coal firing failed. It is now blocked off without any adverse effect on steaming.
I use domestic smokeless fuel rather than coal, Homefire brand. This burns with a hot flame and leaves very little ash and no clinker. I have not had so much success with anthracite or steam coal.
It is essential to test boilers before use. This boiler normally operates at about 50 psi, with safety valve set to 70 psi. I have tested it hydraulically to 200 psi. Normal practice for larger model engineering size boilers is firstly a hydraulic test to confirm the construction is safe. This is followed by a steam test which ensures the safety valve(s) is correctly set and will pass sufficient steam. Please note: this boiler design does not conform to generally accepted designs for 16mm scale locomotives so would not get a 16mm Narrow Gauge Association boiler test certificate.
