I see that you've got the design restraint of materials choice for specialty crops..is that the big hurdle here?
Does it work out over the lifetime of the unit to use stainless with all its externalities, with pedal power...or is it better to use replaceable wooden structure, with manufactured motors and electric power.
I know you are designing it with recyclable materials. Do you have any thoughts or calcs on this?
Acorn nuts on drive studs slip occasionally, but do not catch and heave the barrel. Wood frame works well, Hemlock and pine from the local mill. Fixed brackets are used to hold the water distribution pipe, Owner is happy, have requests for more, as they are locally produced, the purchased machine components are very durable and wear parts are easily replaced, sustainable and recyclable. Variable speed drive is essential...could be done with belts, but electronics are easier.
One issue with using a belt drive is that the forces on the drive output shaft will be increased in order to create enough grip. The shaft will have to drive the belt, AND hold enough tension to grip. As long as this is considered, it's a good idea, but too much load on a marginally designed shaft will shorten its life.
We're building this unit now in Maine, and I'll post more info as it unfolds. We expect to be using it mid August. We're going with agricultural chain. The protruding screws and nuts on the original worked ok to engage the chain, but the shape of them was a problem. I think using rounded acorn nuts will keep them from snagging and causing the mentioned problems. We'll soon find out.
The rings can be rolled locally, and the quote I got was $54 each, which is high, but if they're correctly made, they'll run true and last forever.
The locals are timber framers and we've got some locust stock, so this washer might become a real work of art. If I could find a bronze gearbox....
I'd think just the electric motor system would suffice as the basic works. Brakes are inherent when you stop the current, variable speed is a given without a tranny. Electric Wheel chair motors/powertrain are a bit underpowered, but it's an idea for a seeder or a planter or utility rig.
Are used BCS components easy to come by?
The folks up here want a root washer as a shared community tool. I've agreed to put one together and this is the only one I've seen up close to date. It is claimed to work well, with some of the comments above noted.
I also wonder if the materials can be upgraded. This one uses Aluminum channel for the structure...durable, but expensive..non-sustainable. How about a rot resistant local wood like white oak or locust? White pine heartwood is pretty good. Cedar is very good. Using a hardwood would increase cost and weight, but would reduce wear issues from the grit/tumbling parts. Maybe a periodic replacement is part of the design. We've got wood.
A drive wheel would work, but needs trial to see if it slips. Top mounted drive stays reasonably dry, but does not benefit from gravity to maintain friction. Needs further tinkering. A combination conveyor drive and barrel rotator is an idea. Odd angles, tho'.
It looks like the variable speed control is a good thing. Motor and controller as shown is about $550.
I don't know about bristles. Maybe available in strips and secured inside?
Great site and project!
I'm building one, based on an example of a near identical unit as shown here. The one here has a Baldor GP7405 drive with the chain rig. Looks like a 1" pitch ag chain driven by a 14 tooth sprocket. Motor output (variable) is listed as 68 rpm Right, it does snag on the protruding screws. Maybe without those screws it would slip.
A belt could work, with the drive on a pivot base and a spring for tension. V-Belt like a 5V or a C size would be robust and give enough grip under low tension.