with the task of making a crankshaft and a crankcase.
I’d like to say the
crankcase was easy to fabricate, but it wasn’t. Between it and the crankshaft bearing caps this little half-inch long part consists of 19 parts including six modified 00-90 screws to hold the caps in place. It took a couple of evenings to get everything to stay together while I soldered other parts to it. (Here’s a tip, use mini alligator clips and wooden spring-type clothes pins.) Now, I don’t own a metal lathe, and I don’t have access to one since I’m no longer a high school industrial arts teacher. Normally, when I have to turn parts, I chuck the work piece in my drill press and use needle files to turn stacks, domes, etc. to shape. Due to the small diameter of the crankshaft, I knew I wasn’t going to be able to do this. I’d end up bending the part as I ap- plied a file to it. The work had to be done between centers. Hmm, I won- dered if I could turn the part on my large wood lathe. I bought a drill cen- ter–nothing more than a Jacobs chuck on a Morse taper–to hold a short length of ³₁₆″ diameter brass rod. I already had a ball bearing center for the other end of the part. I have a wide variety of needle files, and I used many of them to shape a crankshaft blank. After using them to file down the shaft to both sides and be- tween the counterweight blanks, I filed them into roughly a pie-shaped profile and then cut a slot down the middle of each one to form the connecting rod journals. There was nothing precise about making the crankshaft. I simply measured how much room I had in the crankcase and eyeballed the crankshaft to fit. To round the connecting rod jour- nals, I gently stroked their edges off with a hacksaw blade.
I used the valve and connecting rods
from the Keystone kit. There wasn’t enough room to put eccentrics on the crankshaft, and I am simply not crazy enough (yet) to try to scratchbuild bearing caps for HO scale connecting rods. It took quite a while to find and eliminate all the binds in the little mechanism.
Connections After attaching universal joints to the rear truck and the rear of the crankshaft and making a suitable slip joint between them I needed a way to make sure
the mechanism worked
properly. I bought a set of Bachmann E-Z Riders–sets of ball bearings on as- semblies you put under locomotive drivers, or in the case of a Shay, the geared trucks. I hooked up the coreless can motor and applied power. Not only were there still binds in the mecha- nism, which I expected, there was
RAILROAD MODEL CRAFTSMAN
19.
19: The Precision Scale Company two-cylinder engine crosshead guides and cylinder heads are on the scratchbuilt crankcase. Note the bearing caps and 00-90 screws with their heads filed square. After getting this far, the author discovered there was not a lot of space between the front U-joint and the front end of the crankshaft. Careful filing to reduce the length of the U-joints remedied the situation. 20: This bottom view shows the firebox and ash pan at- tached. Note that the universals and slip joints are attached to the front and rear line shafts.
20.
enough resistance in it to cause the motor to heat up. I had a small flat can motor with a reduction gearbox that I had gotten in the hope that it would fit the little engine’s fuel bunker/water tank. It was just a bit too long, but since it would drive the Shay much slower because of the gearbox, I hooked it up to run in the mechanism. After lubing everything with a combination of light oil and automotive rubbing compound–especially the universals– I ran it at a slow forward speed for hours on end. The little motor stayed cool all the while, and I could power it down to the point where I could easily count the revolutions of the crank- shaft. (I decided that since that little gearmotor was so nice, I’d cut off the
front of the coal bunker so I could use it–more on motor choices later.) Run- ning it in reverse was a different story; the single line shaft pinion turned by the rear wheel set of the rear truck would occasionally skip a tooth, which I diagnosed as too much clearance be- tween the lineshaft and the bearing cap on the rear wheel set. I attached the front truck without attaching the universals and slip joint between them and found the driven pinion on the front line shaft did the same thing. I had to dissolve the cyanoacrylate adhe- sive holding the bearing caps in place and reduce the clearance by filing down their undersides and shimming the shaft in its bearing surface with some .002″ brass shim stock. On re-
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