Building a chain drive version of this Huller

Colin Caissie · Apr 21, 2017

New to the forum. Maybe this isn't the exact place to discuss the design challenge, but at least you get to look at a cool machine. Should I post elsewhere?
It is a two man hand powered rice huller from Japan, and is impossible to find anymore. There are copies manufactured in India, but the cost to import them is crazy.
The Maine Rice Project has queried me to build 10 units, and right away I figure the crux will be the drive train which is cast gearing...prohibitive cost for a run of ten units. My specific query involves the limits of chain speed.
The main hand crank input is about 75 rpm, raised by the first combo (112:17) to about 500 and final combo (96:17) to hit 2800. Planning on #40 chain.

Other than 120 degree wrap on the small sprockets, increased center distance of the sprockets and the notion to use a tensioner on the final chain combo, any impressions?

I figure chain will give me the efficiency I need without the high cost of custom gears. Looking for alternate ideas, also.

Any impressions?

Chip Chester · Apr 21, 2017

Don't overlook the flywheel effect of the big gears... even if rpm is low.
Consider adding one to keep the flow going.

Also, leg muscles are bigger -- consider pedal instead of arm power. Consider Shimano sponsorship, too...

Finally, big gears don't always have to be cast, from iron. Is your photo one you can make patterns from? Is a production machine, or museum demonstration? You could CNC the large gear out of ply, or certain plastics, phenolic, etc. if you can cheaply replace them at the end of the season. Or machine gear segments that mount on a toothless carrier.

The smaller gears are probably cost-effective to buy.

It looks like the "manual" for the machine (cast in the side of the large gear) shows direction of rotation and a target RPM of 46.
Chip

Colin Caissie · Apr 21, 2017

Thanks for looking at it. There is a significant increase in effort when a load of grain is dumped in...Ask me how I know? Perhaps more mass added could be effective. Will build a #1 prototype.
I also think pedal power, but the boss thinks the two man arrangement is somehow spirit building...if you've ever run a two man crosscut, you know what I mean..can be some hair pulling.

The original is about 40:1 increase, 75 rpm is where the best hulling occurs. Maybe buckwheat or other grain can be done more slowly.

most of the unit is pretty simple...the interesting part is the impeller and the conical impact ring which imparts unimaginable torque and accelerations to the grains, splitting the hull off.

Illinoyance · Apr 21, 2017

Look up Martin Sprockets and download their gear catalog. Also, check out Boston Gear.

DDoug · Apr 21, 2017

Illinoyance said:
Look up Martin Sprockets and download their gear catalog. Also, check out Boston Gear.

Yup, those gears look plain 'ole right from the catalog.

excello · Apr 21, 2017

Any chance of seeing the impeller and conical impact ring ? Sounds pretty interesting. The machine is pretty neat looking overall.

Actually this whole "Maine Rice Project" thing sounds rather interesting - and a little different !! If you could elaborate it would be appreciated. If you can't, or don't have time for that, I totally understand.

excello

Chip Chester · Apr 21, 2017

I'm thinkin' two-man pedal power. And work out the phase of the drive mechanism so there isn't a dead spot like there is at 3:00 and 9:00 on the original.

Two rowing mechanisms would get all there is to get out of your 'volunteers'.

Maine Rice Project | Indiegogo

Chip

Colin Caissie · Apr 28, 2017

The basic idea of the "conical impact ring is seen in the Forsberg patent #3,098,515, which is a vertical spindle unit, with the addition of a blower to winnow the husks. The Cecoco unit is horizontal spindle, and is hand powered. If a unit was designed along the Forsberg patent, it would need extra power for the winnowing function.

The unit in operation. Cecoco rice huller operating, no load. - YouTube
CeCoCo Rice Huller showing mill end, impeller, and impact ring assembly. - YouTube

Johnny SolidWorks · Apr 28, 2017

Keep us updated on the project - it looks to be interesting, if for no other reason than I've never seen anyone make a man-powered rice huller before

If you want any engineering assistance (I'm a BSME who works as a machine designer) feel free to reach out via private message - seems like a cool, fun project (as long as I don't have to directly interact with the hippies

)

Erich · May 5, 2017

Use flat plate. Have a water jet cut the gear teeth. For this application, the jet will make gear teeth that are accurate enough.

Colin Caissie · Jun 7, 2017

Update:

Gears are too expensive. Boston Gear stock was about $500 for the big one. Bought USTsubaki sprockets and cheap chain online. Was under the impression that chain was less efficient than gear, but not a lot.

Problem...Compared to the original unit, the amount of force to run the chain drive system is much higher. I worked through chain tension, alignment and possible shaft binding, etc. I experienced drag and figured it would maybe work out, but it's much stiffer than the gear version, which spins freely and has a nice flywheel effect.

Maybe you can't get the same efficiency when OVERDRIVING i.e. speed increase, but really? Since this unit is a hand powered one, it really matters.

This arrangement with chain may not work. Any impressions?

CalG · Jun 7, 2017

Colin Caissie said:
Update:

Gears are too expensive. Boston Gear stock was about $500 for the big one. Bought USTsubaki sprockets and cheap chain online. Was under the impression that chain was less efficient than gear, but not a lot.

Problem...Compared to the original unit, the amount of force to run the chain drive system is much higher. I worked through chain tension, alignment and possible shaft binding, etc. I experienced drag and figured it would maybe work out, but it's much stiffer than the gear version, which spins freely and has a nice flywheel effect.

Maybe you can't get the same efficiency when OVERDRIVING i.e. speed increase, but really? Since this unit is a hand powered one, it really matters.

This arrangement with chain may not work. Any impressions?View attachment 200558 View attachment 200559

Yes,

Put a motor on it! Electric or internal combustion. Your program effort is described as education, not physical fitness. This is not the third world,

Don't make eating rice a primitive, it will not taste any better.

eta

A tractor pto drive with a two belt pulley speed increase would be ideal. Tractor engine speed could be used to optimize huller performance.

Chip Chester · Jun 7, 2017

I would think more slack would help, with a floating tensioning device, like a 10-speed bike. Create the flywheel effect by installing weights on your large sprockets around the periphery... assuming they get going at a good clip.

Chip

Colin Caissie · Jun 30, 2017

Well, project moving ahead. The increased effort using chain may work out. The user of the original unit was doing about 75 rpm by my timing, which resulted in a final impeller speed of about 2800. The "recommended" final speed would have been 1700 rpm.

I suspect the extra force required may come from the small sprockets (17T) being overdriven ...just an instinctive hunch. Almost no data available for efficiency in such a system.

I may throw a 21-24T or other less drastic ratio in there to see if it helps.

I had looked at lighter chain, but there are no stock #25 pitch sprockets in the sizes I need...100T or so. Water jet cutting.... and on and on...

Yes, pedal power, and my final hole card is a motor. The idea was to have an interactive manual type of machine, a locally produced small grain grower sized machine, and a functional rice huller. Pick any TWO.

lely1103 · Jul 3, 2017

I would think more slack would help, with a floating tensioning device, like a 10-speed bike.
The idea was to have an interactive manual type of machine, a locally produced small grain grower sized machine, and a functional rice huller.

trevj · Jul 7, 2017

CalG said:
Yes,

Put a motor on it! Electric or internal combustion. Your program effort is described as education, not physical fitness. This is not the third world,

Don't make eating rice a primitive, it will not taste any better.

eta

A tractor pto drive with a two belt pulley speed increase would be ideal. Tractor engine speed could be used to optimize huller performance.

LOL!

All the third world cell phone vids I have watched, which is a BUNCH, as I was looking to see what was available in small scale affordable grain harvesting equipment, showed the use of either a beat-up tractor, or a even more beat-up gasoline or diesel one cylinder engine as the motive power.

About the only folks still using own power are the wanna-be Amish imitators that think somehow that food tastes better if you were hot sweaty, dusty and miserable several times while it was harvested and processed. Pretty sure even the Amish wouldn't bother, and, like as not, if they ever saw them at it, would point out all the other available sources of power available, like animals, water, compressed air, etc.

Cheers
Trev

Colin Caissie · Aug 8, 2017

lely1103 said:
I would think more slack would help, with a floating tensioning device, like a 10-speed bike.
The idea was to have an interactive manual type of machine, a locally produced small grain grower sized machine, and a functional rice huller.

We tested the unit and it requires more force than the gear unit. Also the hulling action is not as good. I have chosen a higher durometer lining for the impact ring and this helps a bit, but not as good as the original unit.

The customer says that they have a seed separator that they purchased that was very hard to spin initially, but has become easier as the chain and sprockets have more time on them. I'll put a motor on these and run the chain for a bunch of hours to see if the chain load reduces.

You think keeping the chain slack would help? Can you explain? I'm willing to try anything if it makes sense.

Peter from Holland · Aug 8, 2017

How about multi V-belts The big wheel needs no grooves with that ratio
And they can handle a much bigger ratio Perhaps its possible in one step
The bigger mass should be on the high speed side as its more effective there So put a flywheel on the last shaft

Peter

Joe Michaels · Aug 8, 2017

Why not consider using timing (cogged, or toothed) belts ?

Harley Davidson has had great success using a timing belt (or variant of it) for the final drive on many of their motorcycles. Using a stock H-D final drive pulley and possibly machining or purchasing a smaller timing pulley, as well as using stock belts might be a way to get the speed multiplication. Aftermarket H-D final drive pulleys are not expensive and readily adaptable to other uses. H-D claims the final drive belts, under reasonable conditions, should last 100,000 miles. On something like a human powered rice huller, timing belts may well outlast the people using the hullers. The other plus to a timing belt is no lubrication is needed, and it does not need to have as much tension as a vee belt.

Another idea, since you are aiming these devices at underdeveloped regions with little or no money and resources: how about using flywheels from junked truck or tractor engines ? These will have a ring gear which the starting motor drove, and will also have plenty of mass. Making a shaft with a flange and "pilot" to mate up to the flywheel should not be a problem for a shop with minimal tools.
Using a pinion gear off a starter motor (if buying gears proves too expensive) would give a real high gear ratio.

Using something like junked automobile, truck or tractor engine parts may be a way to get the gearing and rotating mass you need.

Tony Quiring · Aug 8, 2017

Beat me to it...

Self service wrecking yards are full of engines.

And they use a big claw to rip the engine out before crushing so you may be able to get one to allow you yo go digging.

Manual shift cars will have the correct type of flywheel but then consider front wheel drive where there is gearing similar to yours between engine and tranny.

We also were going to suggest flywheel at high speed but using additional step up from final shaft to have flywheel both moving faster and more power available back to working shaft.

If you try to do too much gain in rpm in a single step via the tiny gear it requires too much power due to tiny leverage.

There are frictions in every interface and this is harder to overcome via the smaller moment that the tiny gear has.

The engineer above likely will state me wrong (just a home shop thinkineer) or maybe provide general or optimal ratios that would be more effective.

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