Adding a Water Level Gauge to the Saddle Tank

This modification is one of those that may not be really necessary but which makes the drivers life much simpler because you can see at a glance how much water remains in the saddle tank without having to get off and lift the tank cover.  What made it even better was that I had enough material in my scrap box to make it, although the main plate did have to be made from two lengths of brass flat silver soldered together.  The 8 mm diameter glass tube was purchased from R A Barker (see the links page) at the same time as the whistle.
Stafford Steam Locomotive - Saddle Tank Water GaugeThere is nothing very difficult in building this water gauge other than connecting it into the existing saddle tank plumbing and all the parts can be made on a small lathe or using hand tools.  The glass sight tube is mounted using an 'O' ring at either end; the bottom ring being compressed by the gland nut while the top ring simply fits in a groove inside the detachable top block.  To stop sloshing of the water in the saddle tank from affecting the level in the gauge the bulkhead adaptor fitting at the bottom of the gauge that bolts through the cab was only drilled with a 1 mm diameter hole for the water to pass through.  The fun part came in calibrating the gauge because the scale is non linear due to the curving shape of the saddle tank, so an hour or two was spent playing with water and measuring jugs.  To save any of you building the gauge having to do the same I have included the calibration figures below.  They are all referenced to the top edge of the beading that runs around the cab sides.
Full      =  + 36 mm
3/4      =  -- 38 mm
1/2      =  -- 84 mm
Empty = --141 mm

The connection to the saddle tank was made using normal copper tube and cones, but the difficult bit was setting the connector on the saddle tank balance pipe in exactly the rightStafford Steam Locomotive - Tank water gauge plumbing place.  The position on the balance pipe was marked with the pipe still fitted to the loco, and then the pipe was removed and placed flat on the pillar drill table.  A 1/16 inch was then drilled in the correct position.  The pipe union was made with the its 1/8 inch bore not drilled all the way through, but drilled through with a 1/16 inch hole.  A short length of 1/16 inch brass rod was then put through the holes to locate the union exactly on the balance pipe while the joint was silver soldered, after which the union bore was drilled through into the balance pipe using the 1/8 inch drill.  If you do this, make sure that you remove all the swarf from inside the pipes before refitting.

For those of you who have CAD on your computer you can download my CAD drawing in .dwg format by right clicking on the link below and then saving the file on your computer.  Please note that the drawing is predominantly metric and is drawn full size.  Gentoo's Journals provides the drawing "for guidance only" and does not guarantee its accuracy or completeness.

Right click here for the CAD .dwg file.