Pedal-powered everything

I spent some time today thinking about next year’s cider-making hardware. Last year’s pedal-powered cider mill (year 3) was a revelation – we found that with a simple, well-designed pedal mill we could grind apples much faster than the previous year, when we used a 3/4hp garbage disposal with supplementary forced-air cooling. The only shortcoming was that the limited precision of fabrication made it difficult to grind the apples quite as fine as the disposal did; this cost us about 5-10% juice yield. This isn’t the end of the world; the pomace makes good compost, and if we had a hog it would put to better use, but it would be nice to have a human-powered cider mill that was in every way superior to the electric version.

First, to address the matter of making finer pulp. I could make a new, more precise version of the grinder box to tighten up the throat, but I think we would still have the issue of the last little bit of apple slipping through more or less unscathed. What I’d like to do is make new cutters for the grinder with serrations milled into the exposed faces, such that they form 1/4″ wide strips rather than full-width slabs. The serrations would alternate between cutters for superior shredding action. Since Holly managed to score a 3/4″ hex broach on Ebay, we might as well take the opportunity to recreate the cutter drum in polyethylene, since the maple drum won’t last forever.
My gut feeling is that this would make a big difference, but might not get us all the way to optimum shreddage. The next step would be to make two more cylindrical drums with shallow teeth (maybe 120 degree angle; presumably I could find a router bit that would do the job in a jig on the wood lathe, or do it on a milling machine with a rotary table setup). These drums would be set up below the grinder to receive the pulp from the primary cutters, and geared counter-rotating with a slight gap between them. The pulp would be pulled into the nip between the rollers and crushed to the dimension of the gap.

Next, the increased speed of shredding last year exposed the limitation of our 12×12″ press, which was the pride of our year 2 effort and gives about 5-6 gallons of cider per stack. Bushel tubs of pulp from the grinder were queued up in front of the press, and we were forced to compromise between speed and squeezing the last few ounces out of each load. Clearly, a faster and more efficient method of pressing is called for, ideally one that continues the pedal-power aesthetic.

It is a general principle of lean manufacturing that batch operations should be replaced by continuous processes wherever possible, and I suspect that cider pressing is no exception. Poking around online it appears that large cider operations indeed use what’s called a belt filter press, basically consisting of a porous cloth belt that’s run between successively tighter rollers to force the juice through the cloth. It would definitely be sweet to build a bicycle-powered belt press, the question is whether the time involved in designing, building, and debugging the thing would be worth it.

The success of the pedal grinder also gets me wondering what other motorized equipment could be easily replaced with pedal-powered equivalents. Power tools with horizontal shafts that operate at modest speeds are the obvious place to start; I’m tempted to get some more 5/8″ shafting and pillow blocks and throw together a pedal-powered tablesaw, just to see how it would work. Of course, you’d need a partner to pedal while you made the cut, and you’d have to take it easy so as not to bog the blade in the cut (since it’s not hard to bog even a 3hp tablesaw in thick hardwood). But, it should be a dramatic improvement over the efficiency of a handsaw. A bandsaw might be even easier, as the necessary speed is somewhat slower and it’s got modest flywheels built in.

A combo sander unit or a bench grinder could be a pretty easy retrofit, but after that it gets trickier – a jointer seems like a much bigger challenge due to the higher speed necessary, and beyond that you start thinking about right-angle gearboxes or janky twist-chain or twist-belt arrangements to get a vertical shaft (for a drill press, shaper, etc)

The sheer practicality of modern power tools is such that actually doing any of this stuff would be more like an art project than truly useful innovation; even if we lost the grid and there was no gas to run gensets, I would be inclined to hook up a bunch of bicycles to the electromagnetic half of an old Honda generator; less viscerally satisfying but probably more effective and less labor-intensive than repowering each tool individually. It might be worth figuring out which among the consumer units have the most efficient generators. Finding one that ran at 1800 rpm instead of the usual 3600 could be very helpful as well.


2 Responses to “Pedal-powered everything”

  1. Brandon Says:

    “It would definitely be sweet to build a bicycle-powered belt press, the question is whether the time involved in designing, building, and debugging the thing would be worth it.”

    Belt press! Sweet! It would be worth it!


  2. Chris - generator dude Says:

    What a great idea for converting a Honda Generator! I’ve always thought how silly it is that I’m running on my elliptical, using electricity, and watching TIVO, using electricity, at the same time. Seems like I should be able to harness that pedal power to run the tube.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: