It’s a water pump which is what these engines were typically used for, quite often pumping from a well or bore hole up into a storage cistern in the roof of a large house so there was water available at the taps under gravity flow.

It also doubled to keep the power cylinder cool as the water passes from the pump around the water jacket then off to it’s intended use. I was just using air to keep it cool in my video.

The water jacket started much like the furnace with the tube being held by it’s finished OD so it could be bored out but leaving a smaller diameter at the far end but a similar locating spigot at the top.

Some 5mm plate was bored out a little undersize and then a larger counterbore was machined to accommodate the spigot on the tube

There is a flat down one side of the jacket and rather than cut this from solid which would have been a big lump to heat up for silver soldering I opted to weld two pieces of angle iron together. This shot shows the weld being machined flat though final machning will be done after soldering.

I then used the boring head to cut the other side to a curve to match the jacket, also did the block that the water pump fits to at the same setting.

After soldering and a pickle the assembled parts were then treated much like you would a casting, here the top plate has been bored to size and the bottom end 0.2mm smaller so that the liner will drop in most of the way before it becomes tight. The plate was also faced to bring the overall length to finished size.

The bottom just needed drilling and tapping for some bolts that will hold the hot cap in place

With the jacket firmly held between two angle plates the flat side was milled down to the correct offset from the ctr of the jacket, six holes tapped to attach it to the frame and I have just milled out the clearance slot for the flywheel with a 6mm cutter with 1mm corner radius to leave an internal fillet for that cast look.

The block for the pump was also milled down to the final projection, drilled and tapped and the water passage was also drilled and counterbored for a sealing O ring.

A bit more drilling and tapping on the top surface finishes the jacket off, this time they will hold the beam pivot bracket in place.

The hot cap started life as a short length of stainless steel exhaust pipe which can be had in many different sizes on ebay. A disc of stainless sheet was Sif brazed to the bottom and a steel ring silver soldered to the top to form the mounting flange. After soldering the flange was skimmed down to final thickness ensuring it’s face was then true to the axis of the tube.

The flywheel was machined from a slice of 140mm diameter cast iron, here the first side has been faced, the OD finished and the hole bored for the crankshaft.

It was then reversed in the chuck, set to run true and brought down to final thickness.

It was then over to the CNC to give it a bit of shape. I’ve done quite a few flywheels now and the method I have found to work the best is to mount the ER32 Collet with backplate onto the table and hold a piece of suitably sized drill rod in that which keeps the location of the ctr of the flywheel. I can then mill one side and flip it over to do the other and only need ensure that the rim of the flywheel lines up to a mark to index the rotation.

The flywheel is packed up on a couple of 1-2-3 blocks and clamped down. I use the clamps the opposite way round which reduces the height they stand up above the flywheel which means I can run shorter tool stick out with out risking the collet chuck hitting a clamp.

While I was at the CNC I machined the bearing pedestal tops and bottoms from aluminium Then screwed them together to drill and ream the holes on the manual mill

The bracket that the beam pivots on is a “u” shape which I fabricated by milling the inverted tee section and then silver soldering two end pieces to.

The holes for the bronze bearings could then be drilled and reamed, the vertical ends shaped and a notch milled out to clear the flywheel.

A quick trial assembly to see how it looks so far, next will be all those links and levers.

It’s getting close. I have about 140mm in the Y axis add to that 6mm for cutter diameter takes me to 146mm. If I do a similar flywheel where I don’t mill the outer face or outer edges then something like 160mm dia would be my limit.

Though I could do it in segments if I indexed the blank around so something like 300mm dia would be possible doing it that way.

The next thing to be done was the beam that ties everything together. I started with some 2″ x 1/2″ aluminium flat bar and drilled & counterbored some mounting holes in it so it could be held to a machining plate. I also drilled in from the sides for some of the pivot pins while it was a nice easy shape to hold. With it then bolted down to the CNC’s table I removed the majority of the waste from one side with an adaptive tool path, this leaves quite noticeable steps much like the contour lines on a map except these were ar 1mm height increments.

Changing to a 4mm diameter ball nose 4-flute cutter a “scallop” tool path was used to refine the shape, the tool stepping over 0.2mm per pass leaves very little handwork to complete.

The material was then turned over and two similar paths used to machine the opposite side.

Back to the manual mill and with a 6mm cutter the material that had been used to hold the part was separated leaving just 0.25mm thickness at the bottom of the cuts which could be cut through and the surface cleaned up with a file.

A bit of rounding over of the right hand end and that was another part crossed off the list.

The last shapely link required was the one from the end of the beam to the top of the pump rod. I milled a piece of brass to size, reamed two holes and slotted the ends manually before using a similar process to the beam to shape the ends and fish bellied central section.

Thanks, all the bits could be carved out manually but the CNC does help to simplify things once you have learnt how to use it and come up with teh CAD in the first place.

The piston started life as some 45mm continuous cast bar, I turned the OD to fit the previously machined liner and cut a groove where the piston packing goes leaving material beyond that to form the upper link lugs from. Like the Heinrici rather than trying to hollow out the piston from above I removed most of the material from below and created a shallow recess that a disc of cast iron could be pressed into to form the bottom of the piston.

The CNC was then taken advantage of to machine the top flange of the piston with its two flats and leave the lugs standing proud. I also did the eight holes that are used to hold the packing retaining right at the same time though they were tapped by hand. After this photo the lugs were drilled and tapped for pivot pins and then the ends rounded over.

The packing retaining ring is just a simple turned steel “washer” with some holes. I’m not sure whether I will bother with any form of piston ring/packing as if the piston fit is good I’d rather have the lower friction and just run iron on iron. I will decide after test running.

As the displacer rod has to pass through the power piston it needs a sleeve and gland, this is the sleeve being turned, the diameter closest to the tailstock ctr will have a fine thread cut onto it which will hold the sleeve’s flange against the bottom of the piston with a lock nut the other end will be opened out and threaded for the gland nut. There is a 4mm dia reamed hole through the whole length. Again may not need any gland packing.

The gland nut is straightforward turning, threading drilling, reaming then mill the hex before parting off.

The displacer started out as some brass waste pipe, something like 0.35mm wall (0.015″) so I turned a scrap of maple to a tight fit and used that to support the tube while I held it in the 3-jaw to square off the ends. I also held it like this to Emery Coth the chrome off.

The bottom was just a piece of 1mm brass Sif Brazed in place but the top needed to be thicker to accommodate two grub screws so it’s position on the rod could be adjusted. To keep the weight down I hollowed out most of this part just leaving two ribs where the grub screws would go.

After silver soldering the top on it was given a clean up and the two holes for the grub screws drilled and tapped

The yoke that lifts the displacer via two smaller rods that come up from the Tee shaped arms was turned and then held in the indexer to mill the ends to rectangular section and add some holes. After that the ends were rounded over and slotted so the outer bolts can be used to clamp the yoke to the rods.

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.

No I’m not that organised, just try to keep my 3D CAD upto date with anything that gets changed during construction so that if I come back to it the sizes for the next part will be right.

Lube is just a small amount of clock oil which is very thin and light so minimal drag. There is supposed to be a piston seal (ring) but it seems to run well enough without so I have not got that fitted at the moment, just iron piston on iron liner.