pedal powered Wondermill Jr

I got a Wondermill Jr back before Christmas. Just for fun. Ground some red wheat, some barley (that was a flop - we called it "Barely Bread".) My 9yo can turn it but not enough to do much. It's not horrible but I have to change hands a few times to get enough for a loaf. My wife hates this machine, and doesn't like it in her house. So this is about 2/3 making a stand for it to keep it out of the kitchen and have a  more stable platform to grind (our countertops don't work with the edge thingy), and 1/3 about using feet instead of hands (feet are more used to repetitive motion) - so my 9yo can help more.

So I was thinking about a treadle power, but came up with the idea based on a band saw I saw - to use a bicycle freewheel. A treadle is a fixed linkage, and if you're out of sync it'll slow down or kick back. My kid got dad's spastic nerdiness, so I figured the freewheel would be safer than a treadle for him. I was planning to use the bicycle wheel for a flywheel but it just made the whole contraption too big. (Did I mention my wife hates this thing). My neighbor suggested brake rotors and I had a couple laying around rusting - so boom.  Most of my parts are here now - still waiting on a few things. I originally wanted to run the chain through a hole in the top, but I have a bunch of 1/2" plywood laying around from another project and it was ripped smaller than I wanted - so I decided to just move the sprockets off the left side of the table. I'm using pocket screws, 1/2" ply and 2x2 legs.

It's currently tiny - I'm wondering if it needs to be bigger for more stability once you get to jacking it up and down, but I had this stuff on hand, and small is better when it's not in use. I didn't model the chain path in CAD - a lot of work for show, but I'm undecided between using an open loop on an idler like the bandsaw, or just using a closed loop between the pedal and the freewheel and a separate return spring (leaning towards the latter).   I got my adapter plate drilled to bolt the flywheel to the axle, going to weld a pulley sheave axle hub adapter to that, and bolt it to the rotor.  My freewheel mounts to an adapter I bought of ebay but they were drilled oversized, and it lacks a key - haven't decided how to fix that yet. Return it and buy undersized and drill, or try to shim it.

Gaah. Slight problem. My freewheel and the freewheel adapter lucked out both being an odd size (M34.7x1.0) - which is a nonstandard size here (I think it's a french standard). It's not the standard 24tpi. The hole in the adapter has no keyway and it's almost a full 20mm (it was billed as 3/4' / 19.5mm - so I should've known it'd be sloppy but not this sloppy. ) I can't seem to find adapters in this thread from anywhere else. I could just buy another adapter AND freewheel, but I think I might just drill the adapter through twice to give it four set screws so I can center and then solder. Solder in the keyway could be difficult to remove though, but I don't think it'll be an issue.  The same seller has them in 5/8 - so I could get that, dril it to a true 3/4" and then sweat it on for grip.

One my rotor drive plates came out perfect, I screwed the other up marking my holes.  The other side is really just to line things up during assembly and keep the bolts straight that clamp the two together. A bit of a rabbit trail, but it gave me an excuse to get the printer working again while I wait on more parts

I bought a Kreg micro jig for 1/2" ply as I had a bunch, then found it doesn't work without the holder. (Internet lied). That's arriving Monday, snow permitting. I can start making the cabinet then. Also the rest of my chain and sprockets are arriving then.

Decided to order a 5/8 freewheel adapter and drill it out. I may still solder it on rather than cut a keyway but not until it's finished.

50lbs if wheat and 50lbs of oat groats also coming same day. Let's get cracking.. er milling?

Cut the axle shafts to length (impatient and maybe dumb, but I needed at least one short piece for alignment of the holes I drilled). Drilled the adapter plate and drilled/tapped existing holes in the hub adapter shaft bushing. They're way oversized but my drill press can't put metal back and I screwed up on what was a clearance hole and was was a tap hole. I'm honestly surprised I got a 3/8-16 in the skinny flange. But I had to tap the part and the screws will be blind to do it. No space for a nut on the outside. I guess there's nothing saying I can't put it inside. Hmmm

I knew I would regret cutting both shafts. Forgot I changed my design. One needs to be 2-3" longer and I have no pieces long enough.

I think I'm going to try to solder a 3/4" pipe nipple around the shaft in the space between the rotors.

3/4 pipe is way too sloppy for alignment but I found a 1/2" female threaded union and drilled it out to 3/4 (just skimming threads), screwed my pillow blocks down to make an alignment jig. The threads might even help solder wick in there.

I think I'm going to have to redrill the center hole on the plate after bolting the axle shaft adapter. It's just too tight to drive without hammering. since it's bolted from the inside I put loctite red on it.

FYI - do not beat on the ends of shafts. Use a brass punch. DAMHIK. It doesn't take much to swell it enough to not slide through the pillow blocks and sprockets.  I filed a 1" key down enough to slide it through the pillow blocks, got it all lined up, tired of filing now. Will wait until tomorrow to sweat it and take the jig back apart.

Got the carcass screwed together. I was going to glue it and just dry fit it now but since it's so small it makes pocket screws a pitb. So it's assembled.

I had to move the main axle down and still had to inlet the crossbar to fit the flywheel. The mill is on the front for the pic. It goes on the left with the sprocket, but I couldn't mount it without the top.

Oh yeah. Soldering the shafts... The solid 3/4" axles and 1/2" threaded union just scoffed at my little propane torch. It's long enough to go through the blocks and then just enough that I can fasten the sprocket. I think I can make this work without a shaft 1-2" longer, but I suppose if I need it I'll either have to buy a new shaft. It's not much different than an actual rigid shaft coupler in price.

Your assembly looks fantastic (and sound)! Keep up the great work. And there seems to be an excellent transfer of power from foot to grinder in all the examples I've seen.

When it comes to pedal power, what kind of setup do you envision? Do you have a recumbent bicycle on hand, or a way to manipulate your pedal arrangement so that you can be in more of a reclined posture as opposed to a typical, upright bicycle seat? Most of the pedal-powered versions I've seen have a recumbent cycle or some other kind of "legs-forward" design for the human (AKA the "powered unit").

Any thoughts or plans on this you can share at the moment?

Thanks! Got the pedal axle bolted up and flipped the freewheel so it drives in the correct direction.

The pedal is to be a bar that spins on the pedal axle and has its own loop of chain driving the freewheel, with a spring return. It's a one foot standing operation, like the bandsaw or a grinder. It doesn't need gobs of power, you can do it by hand, but I get tired of it, and my 9yo can barely spin the hand crank a few times.

I had intended for it to barely stick out the front, but with the new smaller size, i found while mocking things up today that's going to be a foot/knee banger. Im probably going to lose the "fold up into the machine footprint" idea  but I think it's necessary.

Still need to make the top, but it fits neatly into this little cubby space beside a cube storage shelf.

I think now that the pedal axle is unnecessary. I have to get the entire pedal outside of the footprint. I think I'm going to 3D print a part to grab the sprocket on the freewheel and clamp that to a lever arm and just drive the freewheel directly.

Nathan Stewart wrote:I think now that the pedal axle is unnecessary. I have to get the entire pedal outside of the footprint. I think I'm going to 3D print a part to grab the sprocket on the freewheel and clamp that to a lever arm and just drive the freewheel directly.

Scratch that. I think a simpler and more robust idea is to take the idea from a bicycle chain strap wrench. I'm not just relying on metal to keep plastic from destroying it self that way.

Got the top on. Discovered what was wrong with my table saw fence that had me ready to chuck it in the trash and had me limping along with various skillsaw jigs. Also discovered my chain breaker is for 420 chain and doesn't fit bike chain.

My pedal is basically a chain strap wrench, with some 3d printed spacer parts to hold it square. I'll see how that goes.

The chain will be welded to the bar, the plastic is just to provide some twist resistance and may not be necessary. I got the fits ok now but without some sort of keeper I'm not sure how much good it's doing.

Now that it's almost ready (need to either shim the mount or get an offset master link (in 510, not 410. ) My helper was lamenting loss of the hand crank.

The obvious answer is tell him to suck it up and quit whining but this kid is HFA/Asperger's and anything even close to reasonable that gets willing participation is worth considering.

I plan to proceed as planned and then think about a retrofit. He might still change his mind. But I also thought about using a treadle on the foot pedal and moving the freewheel to the hand crank. That way I could pump and he could spin to his hearts delight. Even if the thing is clicking away (meaning he's not providing power) if it gets him helping it'll be a win.
Hmmm

This is amazing. You know that your wife won't like it anyways, right? But hey, we're loving it.

I'm curious why not using just a bigger handwheel like those old grinder machines?

Thanks for the feedback. I was starting to feel like it wasn't of general interest.

Sourcing s bigger wheel was one reason. Also feet are more acclimated to repetitive motion than hands, in addition to more power available.

Nathan Stewart wrote:The chain will be welded to the bar, the plastic is just to provide some twist resistance and may not be necessary. I got the fits ok now but without some sort of keeper I'm not sure how much good it's doing.

Maybe the plastic can assist with a low-maintenance method of applying lubrication? Or a brush to clean off dust/grains? Not sure how over-engineered you want this to be, but it's possible and just might be very useful.

I'm very interested in this, but I also don't know any of the terminologies you're using, nor have I developed a schema for mechanical problems. So at this point I'll just grab some popcorn and enjoy the show

The pedal is locked to the freewheel. It's internally lubricated, and the table top should keep dust out.

I have an idea for a 2nd freewheel for the crank, but between the pillow block, freewheel & shaft adapter it'd be another $30 on a project that's already a bit over my initial projected cost. Still.. this is partly about a backup plan for feeding a picky eater, and his participation is a big deal to me.

We're sorta just dipping a toe in the hobby prepper thing. I'm not super worried about my fat self starving/Venezuela stuff yet, but this kid literally eats about 6-10 foods, and I worry that even one or two things being hard to find for a few weeks could leave him malnourished. Old timers like to say "if they get hungry enough they'll eat" but for ASD kids who are picky eaters they can literally refuse food to the point where medical intervention is required.

Really proud of this one. Drew this up in Freecad and printed it. It's a snap fit for an eBay freewheel sprocket. Absolutely tickled pink that it fits so snug - I wasn't sure I had enough mastery of Freecad to do the gear that tight.

I did end up taking the 2nd set of pillow blocks off. I'm going to use one and another freewheel as a chain tensioner/hand crank.  This part mounts the crank handle to the freewheel sprocket.

Nathan Stewart wrote:Really proud of this one. [...] Absolutely tickled pink that it fits so snug - I wasn't sure I had enough mastery of Freecad to do the gear that tight.

Looks like professional-quality work to me! You should be very pleased with your final result (and your bread) once this is all done.

The other half of the freewheel crank.  Got a fit close enough to slide in but can hold the weight of the freewheel without falling out.

Broke out the welder for the first time in ages. Mig outdoors blows... literally. Had to crank the flow way up, sun was behind me and it was tough to see the puddle. Plus I'm a duffer and really can't justify the space the machine takes up in my garage, but I didn't make any welds that didn't look ok after enough grinding.

Also cut and drilled another piece of tubing for the new hand crank (was easier to make a new hand crank than try to adapt to the trilobal shaft). A second freewheel is on the way for the hand crank. I also realized today that I need to plan on a chain tensioner. I'd sort of envisioned the crank doing that, but tensioners have to be able to move or else you're just trying to get another exact length match. Still - I have the chain, I might be able to drill it in a location that allows it.

I didn't weld the chain/strap wrench part of the pedal today, and my son was wanting me to hang out with him some more - so I didn't drag the welder back up. Printing another part tonight to hold the pedal. I think it's got enough geometry to hold up, but if not, I'll go back to the welded chain idea.

So close today. I don't have a return spring or tensioner yet, and I needed to grind some flour, so I put the handle back on and.. found out a few things.

The table is too small. It's perfect front to back, but could use some more width.

With that width, I should add the brake rotors that just came off my car this week. I don't yet know if the flywheel needs it, but the cabinet needs some more mass down low. I should probably also swap the felt feet for rubber.

I might need to go back to the separate pedal axle so I can gear up the pedal to flywheel. The actual stroke length is super short - you probably only get about 1/8 turn and that's generous. It's spinning rather leisurely with no load cranking the pedal by hand (since no return spring.)

The mill needs to be closer to the edge for the handle. I cut the corners off the table for clearance and still had to move it to just use the two outer holes .

I think the return spring is going to have to be very stout, and I'm not sure my sloppy fit table can take it. Fortunately I figured out my table saw fence adjustment since I built it and can cut tight fitting parts now on the table saw instead of using the kreg track thingy. It's fine for what it is but it's no table saw substitute.

How is this project coming along?  Very interested in seeing this in action!  Been following for some time but no recent posts!

Yeah, I'd love to read more too!