After many years admiring from afar I am now the owner of a 5″ Poly V model engine. This was a completed model made from a kit. It is a tank locomotive with 2-6-0 wheel format. I have had it boiler and hydraulic tested to meet UK requirements. I am still learning how to drive it. It is so embarrassing to have to push it back in from the furthest point in the club track ….
I have made one or two tweaks to the design.
It has an axle pump, injector and hand pump to get water into the boiler when under pressure. The axle pump is quite efficient but needs careful attention to set the bypass valve to ensure it does not flood the boiler and leave no room for steam. (The bypass valve allows you to divert a varying degree of water back round into the water tank rather than flood the boiler). I found the hand wheels on the valves confusing in that you had no idea where they were set and when in motion you could not see the pump output inside the side tank.
I took the hand wheel off each of the cab valves and made small spur handles tapped 9BA which I mounted into the side of the wheels. The Stevenson collet block was ideal for holding the wheels in the VMB while drilling and tapping the holes. The spur handles were made from 2mm brass rod which I tapped in the lathe, parted to length and then used a graver to shape the ends. While I had tapped the ends to hold them in place on the wheel I did a belt and braces and soft soldered them in place using surface mount solder paste. The end result is a set of wheels that I now have a better knowledge of where they are set to.
The lubricator was giving me hassle in that it did not seem to be delivering oil to the steam way. Lots of experimenting and adjusting did not seem to solve the problem but a change to a thinner steam oil has done the trick.
I have recently been experimenting with a Rosebud Grate on the Polly and there is a spreadsheet in the downloads section on the calculations for the hole array for a given grate area.