OScale Trains

the tapped hole. Ease the edgesaround the end of the pin.Turn the wheel over and removethe excess threaded length downflush with the back of the wheel.Cut or grind a flat screwdriver slotacross the pin in back of the sparewheel. I use my Dremel tool witha thin cut-off wheel. You can seefrom the photo why we’re using aspare wheel! Using a screwdriver,drive the new crankpin out of thespare driver.This is the finished crankpin. It isready to be attached to your “good”driver. With some practice thesepins will be cranked (!) out andmounted at a rate of less than tenminutes each. The trick is to do allthe burnishing, then all the drilling,tapping, and finishing, for the day’sbatch of pins.To prepare the “good” driver,carefully drill a #6-32 tapping holewhere you want the new crankpin.Tap carefully so as to inflict theleast possible stress on what mightbe some pretty soft zinc or brittle cast iron.Start your new crankpin gently into the new threaded hole.Turn the driver over and, using your screwdriver, “back” thescrew down into the hole, seating it firmly without over-tightening.Check that the exposed end of the pin is completely smooth,with no threads beyond theouter surface of the wheel. Ifthey are out there, remove thepin and slightly countersinkthe hole from the outer surface,reinsert, and snug the pinagain. When you are satisfiedwith the setting of the pin, puta small drop of Locktite or thinCA on the threads at the backof the wheel. The “glue” will wick up the threads into the wheeland hold it with almost no stress on the wheel. A nice hex-headand washer in the crankpin and you’re ready to go.This is a Varney wheel from the 1950s, cast in what appearsto be a good quality zinc alloy. It’s a beautiful wheel, but seemsa little fragile. Its fragility is what led to this crankpin technique.There’s very little distorting stress on the thin casting, and thelarge mating surfaceof the threads disburseswhat stressesthere will be duringoperation.These pins arealso working wellin cast iron wheels,cast iron tendingto brittleness ratherthan softness. Eitherway, less stressis better. Happymodeling. It’s a funhobby!u46 • O Scale Trains - Sept/Oct ’06