At last I am in the final stretch for finishing my boiler project. This phase of the build will wrap up the steam engine series nicely with a self contained steam plant system that should last for many years. I am really excited to see if my pump idea will work with my engine so lets get building!!!!!
The feed pump casting I have chosen won’t work as is because the connecting rod will be at a inclined angle to the eccentric crank. This means that the pump housing must also be angled to line up with the crank angle. This is why I decided to remove the existing mounting base from the pump housing so a new angled base could be attached to the pump housing. The base was easily removed with a bandsaw.....
To make a new pump base I will be using some 1-1/4” x 1/8” angle iron...
I cut the new base to reflect a 12° incline for the pump housing....
Holes were also drilled to accommodate the 10-24 stainless hardware that will attach the housing to the base.....
Using some of the 3/8 piston rod material I was able to check the pump housing angle and set the pump mounting position as seen below....
A 5/16” brass connecting rod was cut to about 4.75” long and threaded for use with the new eccentric & connecting rod yokes.....
Before assembly of the parts I decided to paint the pump housing, base and eccentric parts with the green enamel paint used before on the engine....
Once the paint dried I was able to assemble the pump and base. I used two 10-24 stainless screws and nuts to secure the base to the housing...
The next step was to install the pump fittings. I am incorporating a bypass valve to the pump system so that the amount of water being pumped into the boiler can be metered. When this valve is properly adjusted it will force just the right amount of water into the boiler to compensate for water usage....
I used a 1/16” NPT angled globe valve for the bypass valve as seen below. I will just have to connect the suction side of the pump with the pressure side (globe valve) via a 5/32” bypass tube....
I could now install the eccentric hub on the crankshaft as well as the connecting rod parts and such. I positioned the hub’s top dead center to be at bottom dead center of the crankshaft (78° offset). This will push the pump piston when the engine’s piston is on the down stroke. I chose the down stroke instead of the up stroke as the engine has a little more power on the down stroke due to the volumetric loss of the piston rod side of the piston. I adjusted the connecting rod so the throw of the pump’s piston was perfect.....
I used some 5/32” copper tube to make the bypass tube. This tube was bent with the aid of filling it with molten lead (used as a mandrel). Once the tube was shaped correctly the lead was melted and removed from the tube. This method was used to prevent the thin walled tube from kinking during the bending process....
I wanted the existing hand pump to still be a part of the system so I plumbed the new water pump through the existing pump allowing it to work as a backup pump. This is also helpful as the hand pump can still be used to hydrostatically test the boiler from time to time......
I tested the system for leaks and then ran compressed air through the engine to see if the pump would move water (not shown). Sure enough the pump was filling the boiler with no problem. The only thing to do now was to test the pump under full boiler pressure......
I fired up the boiler for a live steam test and got the engine up to operating temperature (with the bypass valve opened). I slowly closed the bypass valve until I could hear the engine working a little harder. I then monitored the boiler sight glass for changes in water level. Without hardly any effort the pump could keep up with the water usage of the boiler :0) I could tell that the pump was working by pushing on the manual pump’s handle and feeling the engine pump’s pressure pushing back. I closed the bypass valve completely and noticed that the pump could overcome the water usage easily and fill up the sight glass in only a few minutes. In fact I did a little research and found that the pump can move about 4.5 oz of water a minute at 150 RPM. The boiler uses about 1.2 to 1.4 ounces of water per minute so the pump can easily keep up with the demand. If I set the bypass valve very carefully the boiler water level needs very little attention with the exception of watching the sight glass to be sure. I am super “stoked” at this addition to my boiler system :0)
I have since ran the engine for several hours using the boiler feed pump and have found it’s performance to be rock solid. Not only does it make the boilers operation easier it beautifies the engine quite a bit. The eccentric cranks really look cool when they oppose each other as the the engine chugs away :0)
With the completion of this project I am more confident in my machining skills which puts me a bit closer to taking on a scale locomotive project one day. However I may choose to be retired before I take on a project like that. Hopefully my son will take an interest in the hobby and help me in the shop when I tackle that build :0)
Overall I really enjoyed this project and I expect to be able to enjoy this engine for many years. I hope to pass it on to my son one day and maybe he will pass it on to his son one day too :0) Thanks so much for joining me on this journey and for your supportive comments to the site. I am honored to be able to entertain my readers and I hope to keep doing so in the future. So now the big question is what’s next?????
Till then take care my friends and keep on building!!!
Sincerely, Don R. Giandomenico - author - rcdon.com
