Fywheels on the Baker engines all had five spokes which makes them a bit hard to hold using my preferred method of the 4-jaw chuck bearing on the inside of the rim, and the 3-jaw fits no better. So I had to go with a faceplate. This is not quite straight forward as there are a couple of protrusions on the spokes which are part of the governor workings. So I had to use a disc of MDF between the faceplate and flywheel with suitable holes to clear these and the hold down bolts.
Here is the first side being done. First, I lightly faced and centre drilled the waste in the middle where there was extra material. The live centre then gave a bit more support while the rim was machined.
I then bored the hole to a nice fit on the crankshaft and also skimmed down the outside of the waste before turning the flywheel over to do the other side
Due to the hold down bolts I was only able to face back the three bosses that take the drive pulley so had to hold the 3-jaw to cut the step that locates the pulley rim, I knew that waste material would come in handy.
The engine is balanced by grooves cut on the inside of the rim with a 7/16 ball ended cutter. These are quite pricey in ‘metrificated’ England so I went with an 11mm one at about 1/3rd the price and I doubt the 0.005" difference will matter. It was a bit hairy using my 6" rotary table with the 9.5" flywheels due to the overhang and backlash, but the cuts turned out OK in the end. The rim is just rubbing on that angle plate to stop it deflecting under the pressure of the cutter.
The castings have some rather rough nuts and bold heads cast into them, rather than try to clean these up I cut them off, filed the face flat and ground a shallow hole. Then I made up some dummy ones from steel with a short spigot on the undersides so they could be bonded into the hole with JB weld, looks like I also made the needle valve that day.
I fabricated the pulley. Starting with some ERW tube and a few off cuts of 1/8" steel suitably shaped (freehand on the belt sander) to the inside curve these were silver soldered together.
The holes were then drilled at the same setting as the ones in the flywheel so they would all line up OK
I then set the flywheel on an expanding mandrel and used that to hold the pulley while it was trued up and the outer face crowned.
The rotary table was centred on the mill spindle and then each mounting lug in turn centred to the mill and rounded over.
And the finished pulley, I've left the inside a bit rough as its supposed to be a cast surface.
The video below is of machining the slightly larger Galloway engine flywheel. It is 10,2” dia and the lathe running at 250 rpm. The Monitor was around 275 rpm with a 0.020” depth of cut and feed of 0.002” per rev.
Part 1 part 2 part 3 Part 4 Part 5 Part 6 Part 7 Part 8 Part 9 Part 10 Part 11
