The Z3 ran in the Northwest servicing the areas around Couer d' Alenes lake in Idaho in the fifties. This area produced wealth in silver and gold exceeding the famed Comstock Lode of Nevada.
I love doing these standard gauge compounds. Although they can be tricky, when they are running correctly, they are a thing of beauty and awesome power.
The photo below shows the size of the low pressure cylinder on the Z3
And here is the whole engine in operation
The only drawing I was able to find is this from the NW Historical Society which doesn't show much detail so I will need to rely on photos for most of my detail. There were a couple of HO models of the engine and they are usually pretty good about detail but if they had to go by the same info I have there could some discrepancies.
I have the wheels on order and Dennis is cutting out the frame rails on the CNC mill. So I start with the cylinders.
A trip to the metal yard gets me started on the job.
The cylinder is machined from square stock. The bores will be .750" and 1". The LP cylinder used slide valves so the valve ports are in the cylinder block Wood wedges are cut to hold the block at the right angle while the ports are drilled out. The drill bit shows the path the drill will take. Note the wide valve ports needed for the LP cylinder
The LP cyl has a piston rod extension. I duplicate a non-functioning one and make a cylinder cover that covers the cylinder head.
The HP cylinders had piston valves. I am using slide valves with a cross port plate. To duplicate the piston valve appearance, I first make my cylinder and valve covers from aluminum stock. The cylinder cover fits over the cylinder head which is 1" in diameter. I then cut a 1" hole in a .032" brass sheet with a step drill and spray it with layout dye. I place it over the head and scribe the outline.
And on the band saw and 1" belt sander I trim it to fit and cut and shape on the belt sander Poplar strips which are taped on for fitting.
Finally, a side cover is rivet embossed, annealed, and bent to shape and soldered on to the front sheet.
And here are the two engines as they will appear on the frames.
I love doing these standard gauge compounds. Although they can be tricky, when they are running correctly, they are a thing of beauty and awesome power.
The photo below shows the size of the low pressure cylinder on the Z3
And here is the whole engine in operation
The only drawing I was able to find is this from the NW Historical Society which doesn't show much detail so I will need to rely on photos for most of my detail. There were a couple of HO models of the engine and they are usually pretty good about detail but if they had to go by the same info I have there could some discrepancies.
I have the wheels on order and Dennis is cutting out the frame rails on the CNC mill. So I start with the cylinders.
A trip to the metal yard gets me started on the job.
The cylinder is machined from square stock. The bores will be .750" and 1". The LP cylinder used slide valves so the valve ports are in the cylinder block Wood wedges are cut to hold the block at the right angle while the ports are drilled out. The drill bit shows the path the drill will take. Note the wide valve ports needed for the LP cylinder
The LP cyl has a piston rod extension. I duplicate a non-functioning one and make a cylinder cover that covers the cylinder head.
The HP cylinders had piston valves. I am using slide valves with a cross port plate. To duplicate the piston valve appearance, I first make my cylinder and valve covers from aluminum stock. The cylinder cover fits over the cylinder head which is 1" in diameter. I then cut a 1" hole in a .032" brass sheet with a step drill and spray it with layout dye. I place it over the head and scribe the outline.
And on the band saw and 1" belt sander I trim it to fit and cut and shape on the belt sander Poplar strips which are taped on for fitting.
Finally, a side cover is rivet embossed, annealed, and bent to shape and soldered on to the front sheet.
And here are the two engines as they will appear on the frames.