Bicycles,angle grinders, and flexible shafts...

I would like to create a pedal or treadle powered flywheel, and power a leaf grinder/chaff cutter off of it.
One issue I anticipate is translating rotation from one plane to another.
I've recently stumble on two ideas.

While looking around at other pedal powered devices I saw a propeller build that used the linkage from a junk angle grinder.
This kind of blew my mind!
Not only will it change the plane of rotation, it also  has a 1to2 or 3 gearing ratio.

The other idea was to use a flexible shaft grinder attachment.
This would change the plane of rotation and also allow the rotation energy to be placed 3 or 4 feet from the point of origin.

With these solutions in mind, I am encouraged to design the treadle and flywheel portions of the chaff cutter.

I am pretty certain the device should be used from a standing position,  but I'm not sure how portable,it needs to be.
Making one for each garden I'm liable want one in seems reasonable, right now.

I can't wait to see what you come up with.

A belt and pulley system can twist 90 degrees and would be easy to change ratios if you have some pulleys on hand.

William Bronson wrote:I am pretty certain the device should be used from a standing position,  but I'm not sure how portable,it needs to be.
Making one for each garden I'm liable want one in seems reasonable, right now.

I'd suggest you base your machine off a recumbent cycle. From what I understand, it's easier for most people to pedal leaning back in the chair instead of balanced on a bicycle seat. This may be even more apparent when you start using that machine for long periods of time (in excess of 15 minutes).

Good luck! This seems like an exciting project. :)

 I am inspired by the manual chaff cutters I've seen that are basically steel flywheels with blades for spokes.
One person feeds the machine and another spins the wheel.
 I am designing for single person operation.
To feed the machine, standing is preferable.
That makes pedaling impractical.
A treadle driving a flywheel will hopefully make it possible to keep the blades spinning by pumping intermittently.

You can still have more than one person operating the machine, in fact I'm hoping that the standing position will let people swap back and forth easily.

I've been doodling designs today and I'm starting to think the parts retained from the bicycle will be minimal.

I think the freewheeling axel that most bikes have is the key to what I want.
You know how you can pedal in reverse, without engaging the bicycles gears, then pedal forward again?
That's the important thing I'm trying to capture.
Freewheeling lathes using bike parts were a thing.
They used a flywheel, a treadle and were operated from a standing position.


I'd suspected I would discard the spokes and maybe the rim of the bike wheel, and cast a flywheel around the hub.
Now I'm thinking I should cast one wheel,  spokes and all, in concrete, and have it inline with a separate freewheeling hub.

I need to go play with the parts hands on, to get any further.

This Permies thread and specifically, video expose' might provide you with more insight and inspiration.

https://permies.com/t/7535/tech/manual-flour-mill-attached-stationary#159700

Also, there's another thread where someone wanted to build an upright/standing grain grinder, called a Wondermill Jr. This thread may also be useful.

https://permies.com/t/174412/pedal-powered-Wondermill-Jr

I always point people in the direction of the Grain Bikes for pedal powered farm mech, just to see a fairly sophisticated pedal powered machine with a lot of linkages going different directions: https://projects.sare.org/sare_project/one16-277/

I agree that an angle grinder gearbox would work fine, or perhaps a worm-drive gear out of a dead skillsaw. However, pretty much every dead grinder or saw that i've ever seen had died due to the gearbox failing, so it might be hit or miss tearing apart tools.

Maybe easier than hacking old tools would just be to get a new 90 degree gearbox or two: https://www.mcmaster.com/90-degree-gear-boxes/

I've never had good luck with flexi-shaft power transmission, but I'm sure there are ways to make them work great.

Your point about going from pedals > freewheel > flywheel is absolutely necessary because you want to be able to stop pedaling without the pedals tearing your legs off.

There are also the right angle drill attachments that you can buy. This one is made in America and they sell all of the replacement parts.

Tight Fit Tools Right Angle Drill Attachment

The ones from Harbor Freight use a standard drill chuck. But Tight Fit's either use a threaded shaft for their own bits or a hex chuck.

Lots of great links for me to follow-up on!
Here's a freewheel powered bandsaw that is close to what I'm aiming for:

https://www.mortiseandtenonmag.com/blogs/blog/the-human-powered-bandsaw

The "pedal powered Wondermill Jr" is almost exactly what I'm trying to do, only I don't know how to machine or weld, cant afford proper materials, and I also don't know the proper terminology!

To make up for those deficits I'm gonna stick to building with junk so I can afford to learn as I go.
This is preferable really.
I am motivated to build things that are reproducible with minimal tools and materials, in the hopes that it will someday make a difference for someone else.