< Crossheads >
Crosshead is built up from a laser-cut 12mm body, laser-cut 3.2mm side plates and a bush.
First the body and the side plates are fixed by annealed brass nails as rivets, and then silver-soldered. Next the bush turned from a steel round bar is push into the body and soldered. After all, nail heads are removed with a file.
The center hole for piston rod is drilled and reamed.
The upper and lower sliding grooves are finished by end mill. To ensure equal distance from the center to both sliding grooves, I prepared a dummy rod and hold the crosshead in the vise as the photo shows.
So as to prevent wear of the grooves, I made slippers from 0.5mm phosphor bronze plates.
The chassis is disassembled here. And then the cylinder blocks are mounted on the frames and drilled through the frames.
The slide bars are cut from steel flat bar and bolted on the cylinder back cover. The motion plates are laser-cut and equipped with steel angles. They are fixed on the frames in the same manner as the cylinder blocks.
The slide bars' ends are fixed to the motion plates with steel angles. The crossheads with the piston rods should travel firmly and smoothly. Actually, the crossheads' vertical play is 0.05mm while the horizontal play is 0.2mm.
The inner motion plate has phosphor bronze bushes for slide valve stems. The bushes are finished loose-fit to the motion plate.
The valve stems consist of 5mm and 8mm round bars screwed each other and fixed with lock nuts. Here the bushes are glued into the inside motion plate with Loctite, ensured the valve stems traveling smoothly.
Leaf spring hook brackets are made from steel flat bars. They consist of bracket plates and spacers. They are drilled one hole in each and fixed on the frame with a bolt and a nut, and then the other holes are drilled through the frame.
The gudgeon pins for the crossheads are made here. It is screwed into the crosshead from front side and secured with a lock nut.
Erection of the cylinder block related components are finished. The cross heads and the piston rods will be fixed with taper pins, after completion of connecting rods.
Cast iron parts are delivered at last. The material is ductile iron. I will start from the wheels next month.