After the distractions of a couple of other engines I got back to this one to do the last part which was the water pump. Not only is pumping water the main use for these engines but the water also serves to pump the cooling water around the cylinder before exiting to it's final destination.
Looking at photos of full size and the Patent the 1/4 scale drawings were not quite right externally so I drew mine to hopefully be a bit closer to the original, the most noticeable feature that I added was the flange where the bottom of the pump mounts to the main body though mine is a dummy.
I started by facing and then milling two flats along the length of some 1" brass bar so that I had some ref faces to work with and then drilled, reamed and tapped the long holes using the 4-jaw. Then over to the CNC firstly with an adaptive path to rough out from one side.
Then a couple of finishing paths though the majority was done with a scallop using a 3mm dia ball nose cutter stepping over 0.2mm per pass. After that it was flipped over and the other side cut.
The bottom flange was also machined on the CNC before being "parted off" with a slitting saw
The flange and a piece of flat material were then silver soldered to the body, the flat material milled to final size and thickness then drilled along with a few other cross passages. The remaining parts were just turning and a bit of milling to form the hexagons.
All seems to move as it should once assembled, just got to make the pivot pin to replace the 3mm machine reamer I am using in the photo.
I'm undecided about how much plumbing I will do. I generally run my engines for short periods and therefore don't put water in the hoppers so will not really need any water circulating and there is little point in making and fitting dampers when the engine is not pumping to any head or against the restriction of long pipe runs so may just go with a couple of short stubs of pipe. If that is the case then all is ready to start painting.
