RODS AND VALVES

The moment of truth came when I fixed the first pair of coupling rods in place. Nice smooth action until suddenly it locked solid. This was no tight spot; far too solid for that. Something really had gone awry. I spent a long time carefully measuring distances between crankpin centres but they were both exactly as they should be at 8 inches. So it could only be that the quartering had slipped. This meant getting the engine back on the bench, turning it on its side and stripping out pipework and pump eccentrics so that the wheels could be dropped out.

I do my quartering in the lathe with a simple jig. Setting up the first axle, I could see it was out. I decided the jig needed to be more rigid and so spent more time doing that. Of course, the hard part is removing a wheel from the axle. Heating it up to break the loctite and then supporting it while thumping it with a lump hammer and a soft block! Eventually it came off and after cleaning, I reassembled and put on the loctite. This time I made sure the wheel couldn't slip by wedging it in place with the tool in the cross-slide until I felt sure the stuff had set. Then I drilled out the pin hole and put in a new pin. The other two axles seemed to be OK.

Getting it back on to the trolley hoist, I was able to try out the first pair of coupling rods in a rolling position. Just one slight tight spot.

I seem to have been short of workshop time this month. I've been side tracked several times. Making the rods for the other side was very time consuming and on top of that, I wanted to get a really good finish. Then after fitting, I lost count of the number of times I had to take off the rods, find witness marks for the high spots, rub them down and try again. I wasn't satisfied until I could push the engine along the rails without any undue effort. Next came the conrods. Each time a component is added, the drag increases until finally all bits are fitted. Needless to say, it is not free enough to push along the rails. I will need to get it running on air for a while to free everything. So before that can happen, I will have to make all the valve gear and set it up.

VALVE GEAR

Some of the valve gear has already been made. The first job was to make the weigh shaft. A simple turning exercise but it had to be supported by brackets either side, which needed to be aligned. A bit of careful filing on the underside of the brackets and the shaft slid between and easily turned. I used a piece of EN1A which I had, but I might change it for stainless as it's not going to be painted and avoid any rust in the future. Next came the return cranks. These are made from a piece of 1 x 1/2 lump of steel. I followed the original drawing, although I'm not sure that they need to be so complicated. I drilled and machined on the mill, as much as possible. Then I stuck them together with super glue and finished shaping them on the sander. Being so thick, the sander does a good job and keeps the sides perfectly flat and at right angles to the plane. A tap with a mallet and they come apart to be finished off. Rust can be seen forming on the inside of the holes, which is where I cooled them in water! The sander generates a lot of frictional heat but the super glue seemed unaffected.

Next is the eccentric rods. The ones on the drawing are awkward to make, so I simplified them. I have, of course, stuck to the critical dimensions. As can be seen in the photo, the bearing block is a solid lump of bronze with a reamed hole. I used superglue to glue on the bottom plate, and then drilled through the bronze. This made sure it all lined up. Then they were finished on the linisher. In the photo they are held together with bolts, but I will be fitting studs and nuts.

This was as far as I could get in the time this month.