Crossheads are always quite fun to make. Silver soldering is a good way of ensuring that at least the piston and inner crocodile are nice and solid. The starting point is a piece of thick metal (0.7mm thick) to fit between the slide bars with a notch at one end to accommodate the 0.5 mm diameter piston. This also benefits from having some flats filed on to it to give a more precise location.
The silver solder was in a paste form and very easy to flash the joint with a little gas flame.
This was then placed in the vice and the socket for the piston filed into the end, rounding off the corners, taking advantage of the safe sided file.
Alignment in the slide bars was then checked: at this point it should be a tight fit.
Followed by a 1mm diameter hole to accommodate the little end of the connecting rod.
This was then opened out rearwards to be able take connecting rod. The outer face of the cross head can also be seen resting against the slide bars.
Making two of anything can be easily achieved by sweating two pieces of metal together and roughing out the shape, just once, then separating them. The little end pivot hole is 0.3mm diameter.
The two components were soldered together using a tapered stainless steel pin to stabilise the outer face by holding it on a charcoal block whilst the inner face was held onto it with downward pressure on the piston. This assembly was joined with electrical, relatively high melting point soft solder, as I didn’t fancy my chances at the whole lot not melting down into a blob if I tried to hard solder it. I normally use steel for valve gear - which would be less likely to melt, but as this is kit is etched nickel silver, that is what I have used here.
A tight but smooth fit is what was aimed for at this stage. Subsequently, the mating surfaces of the cross head slippers were filed using a slotting file to give a running clearance with the groove locating the cross head on the slide bars.
The outer cross head face was filed to represent the prototype and the piston socket dressed to look more convincing. The little end of the connecting rod will have a pin silver soldered to it and the round outer boss of the cross head will be represented by a washer soldered onto this pin to hold it in place.
It never ceases to amaze me what you can do with a phone camera.