Building the Stuart boiler feed pump part 1

I had always been fascinated by the boiler feed pumps that were used to top up boilers used in mills and factories, they seemed to me to be the unsung heroes, gently pumping away while all the attention was focused on the engine. There are other ways of getting water into boilers: engine driven pumps, injectors, hand pumps (on small boilers). But none appeal as much as the steam pump.

There are several casting sets/kits available to build pumps in different sizes, I have a small (4") vertical boiler (GLR) which I built years ago and had done nothing with. I thought that a small feed pump would be a good centre piece in a steam plant, which I could then use to power small stationary engines.

Boiler feed pumps are self starting irrespective of whether they are single or twin cylinder. Two cylinder pumps are perhaps a little easier to build as they use a simpler steam valve arrangement whereas the single cylinder ones use a shuttle piston in the valve chest to control the steam.

After some research it became apparent that the only candidate was the Stuart Models version. It is tiny, only 6" long with a 1/2" bore and stroke of 3/4". These little pumps have a reputation for being difficult to build and set up. I was told by several "experts" that they were almost impossible to build as the steam passages are all very close together and even if one succeeds in this trying to get everything steam tight would be a challenge. Stuart Models say that "The Steam Boiler Feed Pump is a most interesting model to build requiring good workmanship". How hard can it be? You can find out as the blog continues.........