CP Executive train in Albany

CP Executive train in Albany

Friday, February 1, 2019

BAGRS live steam locomotive (Gauge 1) - Part. 3

I was able to sneak an hour or two in at the workbench recently, which allowed me to press forward on this engine. Previously, I had secured a sprocket to one of the axles and now it was time to connect it up to the motor.

There are four sprockets that tie everything together: one is connected to the end of the motor, which is then chained to a second sprocket on a rotating idler shaft containing a third sprocket, which is then chained to the fourth sprocket on the axle. The sprockets are bored to accept different shaft sizes, and to make up the difference the plans called for K&S brass tubing in telescoping sizes that increase in diameter as necessary Then, the set screws on the sprockets are tightened and compress the tubing together which retains the sprocket. I didn't believe it would work but it did. However, if those joints eventually fail I may just turn a shaft to the proper diameters and skip the tubing bushings altogether.

The idler shaft support is utter simplicity, being a piece of 1/32" brass that was drilled and then bent. Because I wasn't paying attention entirely to what I was doing, I got to make it twice. Drilling slowly and carefully into the thin bronze with the drill press was required; otherwise, the bit would grab and spin the part around. That didn't happen, thankfully. Then, the holes were deburred and the two actual bearing holes were opened slightly with a file. The support bracket was then formed in the vice. I could have used pliers to bend it, but I was concerned that the bends wouldn't be 90-degree and thus the ends wouldn't line up. That is difficult to correct by re-bending without overworking the thin brass, and not wanting to make it a third time I pulled out the vice. A little hammer work and it was done.

Before the idler shaft could be installed in the bracket, I had to make the two chains that connect the sprockets on it to the other sprockets. I bought plenty of extra chain but I still had to be careful to count the links (24 for one, 33 for the other) and then form up the one that joined the new ends together. I tested the chains and found that one bound up at the joint I made so I carefully adjusted the bent-over ends until it ran friction free. (This engine produces so little power than any friction can seriously hamper it). Then, I aligned the sprockets on the bracket over the sprocket on the axle and screwed it down to the deck. I marked the hole locations and pre-drilled them first to prevent the boards from splitting.

The motor is an oscillating cylinder that came with the boiler kit. It has connections for the steam lines in and out, a flywheel on the back (or front, depending on perspective), and a spring to adjust the amount of pressure the cylinder has on the port block. It all came pre-assembled but the screw might need adjustment after testing. The last sprocket attaches to the end of the shaft that also has the flywheel and a chain connects it to a sprocket on the idler shaft. I made sure everything was in perfect alignment, marked the four mounting holes on the floor deck, and then drilled them out. The motor was then screwed down.

The engine utilizes a simple displacement lubricator which is available from Roundhouse Engineering, one of the oldest Gauge 1 live steam companies still in existence. Their locomotives are simple and despite having multiple models all share a family appearance, but they are also bulletproof. I started another scratchbuilt locomotive years ago based on their parts and may someday get back to it. Anyway, a displacement lubricator works by allowing steam into the body of it from one side, the steam converts to water and sinks to the bottom of the body, and oil gets displaced up and out the other side. Simple, but it works.

I am not sure how Roundhouse mounts them but here I needed to screw it to the deck of the engine. No provision was made for that, so I took some of the 1/32" brass that I had left over (from a first failed attempt at an idler shaft support bracket) and cut it to size. I then used my blowtorch to carefully solder it to the bottom of the displacement lubricator. Of course, I first unscrewed and removed the rubber o-rings can caps. I also was careful to not get it too hot as I didn't want it all to fall apart! Some flux was essential, and I used silver bearing solder because I had it on hand. Had I not honed my skills building the Gauge-1 switches, I probably would have soft soldered this.

Finally, once completely cooled I washed it with alcohol to remove all traces of the flux. Then, I laid it out on the deck and drilled holes for the mounting screws. Too close to the edge of the deck and it might break off, but too far inboard and it could interfere with the boiler. Now that I look at these pictures, I wonder if I should have used hex bolts and nuts instead of Philips head screws. They can always be changed later if I want. I still need to connect everything up with silicone tubing but I have that on hand and it shouldn't be too difficult. I am now contemplating whether I want to paint all this stuff or leave it unfinished brass. I am leaning towards not doing anything to it.

1 comment:

  1. Ben- looking good! I work with First FTC robots(google it) and we are using chain and sprockets that look similar to those, and a lot cheaper. I will try to find out where to get them. Keep up the good work!