Onward with cider equipment upgrades

Holly and I spent this morning in the machine shop, fabricating parts to upgrade the pedal-powered apple grinder. We want the power of two cyclists to operate the grinder, but the technique we used last year was not satisfactory – coupling a tandem bike to the grinder by the fork led to dramatic vibrations, and the setup was marginally stable, leading to a precarious sensation for the pedalers. From an ergonomic and aesthetic standpoint, it would be much better if the two pedalers were side-by-side, and if they could each independently drive the mill. So that’s what we’re implementing.

In the basic pedal mill design, the main grinder drum runs on a 5/8″ shaft, and it’s driven by bike chain from a jackshaft with a ~4:1 increase in speed. The jackshaft had a crude adapter that we made by brazing a steel shaft collar onto the threaded bearing cup of a bottom bracket, which is the same thread as a standard freewheel. So we threaded a freewheel onto the adapter, and drove the freewheel (again with a ~3:1 increase in speed) from the large front chainring of a bike, which bolts on via the front fork. In the modified design, the jackshaft remains, but it is pulled back toward the pedalers and outside of the plywood grinder box, so it can be extended out to the left. We machined a heavy bar of aluminum to support the pillow block that carries the left end of the shaft, and machined a longer 5/8″ jackshaft from a ground stainless rod. Holly turned two aluminum freewheel adapters with a 1.375-24 thread on the OD for the freewheels, and a 5/8″ reamed bore on the ID. As soon as I can find somebody with a suitable 0.1875″ keyway broach I’m going to broach the freewheel adapters and the drive sprocket, so the whole thing can carry serious power without slipping and tearing up the shafts. I’ll post pics as soon as I get it provisionally assembled.

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