Barrel Rider, Community-Cooker


I think im homing in on a useful concept for the semi-industrial cooker.

The basic idea is to scale up the Palestinian cooking utilities, when the peace sets in and hopefully the power returns. This we can do, using SimpleFOC, since the goal here is to make a “stirring device” in order to have larger volumes of eg. Rise-porridge, Dahl, ChickPea-Soup etc. in quantities not possible to stir by hand.

A cylinder with a 50cm radius and a height of 120cm contain 942 Liters.

By making the stator sit on the outside of the vessel, we can make the entire lit and hitherto connected stirring knives/blades spin as the rotor w. permanent magnets attached on the outside where the magnets will be less prone to heating, and we avoid any gears, belts and stuff that might chip or otherwise contaminate the food.

One could call it Direct Drive Lit Stirring ?

Depending on the amount of stator teeth we can create quite a lot of torque. This illustration has 36 stator teeth, each with decent space for windings.

Work in progress.

Creative Commons CC-NC-BY-SA

By making the stator sit on the outside of the vessel, we can make the entire lit and hitherto connected stirring knives/blades spin as the rotor w. permanent magnets attached on the outside

I didn’t really understand this. Wouldn’t the vessel (eventually) get very hot, and demagnetise the magnets?

where the magnets will be less prone to heating, and we avoid any gears, belts and stuff that might chip or otherwise contaminate the food.

While I appreciate the idea of not wanting chips contaminating the food, I think using direct drive to stir is perhaps not the best way to go - there’s no requirement for fine control, precise speed, or anything like that. All mixers I’ve seen so far are uni-directional, not that backlash would be an issue either.
So given the application has basically no requirements at all except that the mixer turn, and some crude level of speed control is possible, I think trying to use direct drive would just require a much bigger motor than if you included some gearing.

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There is the requirement, that it should be able to self clean, like a dishwasher, when a portion is done.

It is a rather large stator and yes the stator may get upwards to :100: Celsius. I suspect the magnets could be kept significantly below boiling degrees, like the handle on a normal lit.

On the upside, it will be rather “easy” to build/assemble/maintain if the basic parts existed, like the stator modules and so on. It does involve a lot of stainless steel.

But you do have a good point about the gears, if kept outside. It could still be the lit turning… :thinking:

Right, induction heating is basically just eddy-current, that is magnetic fields heating a metal eg. Stainless steel (magnetic grade).

That we can work with :face_with_hand_over_mouth:


Imagine this; 17mm pitch or thereabout gear mounted on the outskirts of the lid. The lid will be rolling on bearings attached near the top of the vessel but will also be held in place by bearings rolling in a grove on the gear. So when we attach the gear or gear sections (could be printed in modules) the lid with the stirring-blades “hanging” into the barrel, will sit tight and can only rotate.

There should be openings in the lid of course. The idea is though, to not take of the lid, unless absolutely necessary. If need be, the bottom plate can be taken off for inspection or scrubbing.

By making the bottom plate detachable, we can fit different kind of plates for various purposes. Mainly it should just have a valve (manual or automatic for production line dosing).

The motor mount will be welded to the side of the barrel.

Filling the barrel;

Depending on the final hight of the vessel, it can seam rather daunting to fill numerous gallons of chickens or lentils, washed into it.

This is where the washing, slicing and prepping station comes into the story.

If just a single community-cooker is being used, then one could argue that a person or multiple persons could fill it by walking up and down a rigid ladder/platform.

If on the other hand we find ourselves in a larger production unit with perhaps 10 community-cookers, then some sort of lifting-winch should be in place, transporting the washed beans and other ingredients from the washing/prepping station to the vessel itself.

Regarding the volume;

The US has just promised to provide more than 2 million meals per day, for how long ? Serving what ?

One community-cooker being able to hold, let’s just say 1000 liters, can produce roughly 1000 / 400ml = 2500 meals per half-hour (400ml is a regular can size portion). Ok, let’s use larger buckets :bucket: maybe 10 liters. 10 liters should be possible to carry in a bucket. That’s 200 buckets per hour, per community-cooker.

If the thing is running 24/7 it can produce 2500 meals x 48 half-hours. That’s 120.000 meals.

All this naturally involves access to abundant electricity :zap: if running off-grid on eg. Solar power it will be dependent on the solar farm of course and the storage capacity etc.

How much power can a US navy nuclear class sub provide ?

Can you survive on 400ml per day through?

Consortium foundation;

  1. The principal purpose of the community-cooker-consortium is to provide sustainable basic foods, at scale and competitive, for the people’s of our earth, our home.

  2. The Community-cooker is a large semi-industrial standardized cooking vessel, designed to prepare bulk food suitable for human consumption eg. Chickpeas-soup, lovely-lentil-dish, Dahl etc. at scale. Part of the Community-cooker platform is motorized using the Open-Source SimpleFOC - Field Oriented Control software repository.

  3. The Community-cooker-consortium pledges to create value through healthy meals, not financial value. Our goal is to provide meals as healthy and as affordable as possible. This involves establishing a world wide network of raw-material purchasing and distribution, in collaboration with relevant partners. The main goal is to out-compete unhealthy foods, so as to make the healthy choice the preferred choice both financially and physically. Naturally employees should receive just salary in accordance with local union agreements.

  4. The core values of the Community-cooker-consortium is Christian in nature, taken from the good story of Jesus Christ feeding the masses through humble means, freely. This also entails providing meals for the poor in collaboration with relevant municipalities and state authorities.

  5. The community-cooker-consortium is a social construct, and to underscore the point for our capitalist brothers and sisters, there is no shame in being socially responsible, it is our choice to be so because we love our neighbors indeed we love all members of our societies. We love this earth, our home, and we can see what the unhealthy capitalist exploitation is doing to the environment. This is why we wish to promote sustainable and healthy meals. Too many animals are being slaughtered, the current way of doing business is unsustainable. We have a different vision.

I’m not sure I understand, sorry: the plan is to build a vessel that rotates vertically? If so, there’s no stirring, the food in the rotating pot will simply stay in place, if anything slowly separating like in a centrifuge. And burn where heat is applied. Magnetic stirrer hot plates work differently (a rotating magnet in the base magnetically couples with a non-reactive stirrer bar in the fluid to be stirred)

As someone who was very tangentially involved in industrial food preparation at scale, the problems to solve are incredibly hard: from filling/emptying cooking vessels, to preventing bacterial growth, o sanitizing them, to ensuring every part can be exposed to corrosive and heated fluids, etc. A big vessel full of food weighs too much to be moved, and cannot safely be emptied from the top. Especially when the food is at boiling temperature.

I’m not arguing the technical points of the motor/controller part. I’m asking about how do you envision people using it to cook food safely. And the wisdom (or lack thereof) of a rotating barrel to do so. Unless I completely misunderstand what this is about. When solving an engineering problem, I learned to start from the user scenario, and building back from there. A vision statement should start from “a community needs food, we propose to do x. In order to simplify x, we are building a device that does y”

Also, if the aim is to help feed Palestinians, maybe using Christian religion is not exactly the best way to go :slight_smile: Especially in that part of the world, the last thing people need is more religion.

Yes, the idea is to stir it.

They truly need mercy, forgiveness, peace. I’m not proposing religious indoctrination. I’m proposing true Christian charity. Compassion.

The way forward together


Im thinking something along these lines. A double helical design with a “reverse” center screw. So the outer helical blades pushes the soup/porridge up the edge and the inner screw sends it back down the center. I guess this is a typical industrial method/design.

How fast would you say it should spin? 4-7rpm ?

I’m hoping that a heavy duty stepper (NEMA34/42) will cut it. Depending on rpm and gearing.


Perhaps it is best to continually “scrape” the bottom where the heat will sit?

The idea is to fill it with steaming/boiling water when initiating a new batch. This will significantly reduce overall batch time and the energy required. The bottom heat source “just” have to keep it boiling…

It looks like you never tried cooking a very big pot of lentils. You just don’t dump water and lentils in, then wait. You start by having oil and aromatics, some vegetables and spices added in he right order, and lightly fried/sautéed in the oil, then you add the lentils and a cooking liquid. Pretty much any stew, in order to taste decent, needs more than dumping water and ingredients in. It takes layering of flavors to get a good tasting dish.

My advice: buy a 20 or 40 liters stock pot in a restaurant store, and try making 10-20kg of any stew (lentils are good and cheap) following a simple recipe like this one Lebanese Lentil Soup - A Cedar Spoon or Hearty One-Pot Lentil Stew | The Mediterranean Dish. Try stirring the pot manually and measure the force required. You will discover it takes significantly more force than you think, but also requires much less stirring if you have the right heat source. If you use a jacketed pot, for example, you need no stirring at all. Same with an induction cooker set at around boiling temperature after the initial phase.

Then try properly washing and sanitizing the pot and the stirrer. A stirrer like the one you designed, will be a total nightmare.

And before you say “well, as long as they get calories, who cares”, keep in mind that any culture goes to great lengths making great tasting food, especially when in a hard situation (food as comfort). If calories were all that matters, MREs and protein bars are a solution: easy to transport, easy to distribute, cheap. People must want to cook with your contraption, and produce good food, not slop.

An induction cooker with a controllable heating cycle (hotter for sautéing, 95C - 200F for the liquid phase) will cook a great tasting stew with no stirring required. None. And the pot will be orders of magnitude easier to clean/sanitize. That same induction cooker can also be set in “keep warm mode” to keep the food tasting great for hours, with no bacterial growth, solving yet another problem that your contraption can’t address.

My point is: you are trying to solve a non-problem for something you seem to have no experience with (cooking at scale without getting people sick, I mean). One of my best managers used to say: “when everything else fails, ask the customer what they want” (it was sarcastic: it means that you must always start from solving a customer problem). Find someone who cooks huge batches of food and ask them to spend some time watching them and asking questions. You might then know enough to develop a useful product…

If it were me, I’d build an induction cooker: no moving parts, works much better, easier to clean, great for serving food over extended periods of time. Sure, I could not use SimpleFOC, which I can see it’s a problem if I wanted an excuse to use it :grin:

Those are all good points. I do intend to use induction heating. Could you elaborate on what you mean by induction cooker ?

Why will it not need stirring?

Regarding the frying of onions, garlic, spices etc. that could be part of the process. I made lots of tasty lentil soups also using herbs.

I’m sure you know that the monastic tradition throughout the ages has refined and defined the herbal use for medicine and cooking.

Ps. I did talk with someone with experience in large scale cooking :cook: she told me about the importance of cooling the “product” relatively fast (6-7 hours) before bacteria start growing. I suppose if you serve it straight away, it will not be an issue. Naturally this is super important if storing the stu.

This is seriously off topic for this forum, so this is the last time I answer, to respect other people.

Food sticks to the pot when the pot is hot enough to cause scorching, well above boiling. An induction cooker (Induction cooking - Wikipedia) makes it easy to sense the temperature at the bottom of the pot and regulate power to keep a stable temperature (using a PID or even just a thermostat). As a matter of fact, pretty much any induction cooker these days has temperature control. If the bottom of the pot is at below boiling temperature, there’s no scorching. Heat moves up, so over time all the food in the pot will be at the same temperature.

Any type of food cooks just fine at below boiling temperature. As a matter of fact, as long as there is water in the food, outside of the bottom scorching, the rest of the food cooks at no more than 100C. What it doesn’t happen at below 100C, is the Maillard reaction, responsible for a lot of the flavorful compounds in food. For that you need high temperature (meat “searing”, sautéing, etc) to develop those compounds which then are infused into the stew cooking at lower temperature.

Cooking a stew with the bottom of the pot at 200C or 95C,results in the same flavors and cooking profile, just the former needs constant stirring to avoid sticking and burning, the latter is hands off. I highly recommend to understand why we cook food the way we do. Every recipe is built our of those basic rules, no matter of complex it is.

The problem of induction pots in displaced populations is that it requires electricity, and most of the times it’s easier to have a LPG tank than reliable electricity. But since your solution requires power anyway, might as well use an induction cooker and solve a lot more problems a lot better.

Or, if you want to use gas for cooking, you use a jacketed pot: the way a jacketed pot works, it’s a double walled vessel. You have water in the space between outer and inner layers, and you heat the water or steam. Since water at atmospheric pressure can never be above 100C, the inner surface is never above scorching, and there’s no need to stir. In that case, you’d sauté in a separate pan over the flame, then dump the content into the jacketed pot, add meat/lentils/rice as needed, and walk away until ready.

Electricity or no electricity, there are a lot of better ways to address the original need. You contraption is a waste of time and resources that does not address any real need.

As for "someone with experience in large scale cooking " I hope either you misunderstood what was said, or that person should never be allowed near any food. Yes, if you want to store cooked food at refrigerated temperatures, you need to quickly drop the temperature outside of the "danger zone’ where bacterial growth happens (4C-60C). In 6-7 hours you’d have a bacterial load to kill a small city. You need to use a flash freezer or high speed cooler, and the food should not stay at between 4C and 60 for longer than minutes, not hours. That’s why what that person said would never work outside of an industrial plant where food can be cooled in minutes using powerful coolers. In the field, there’s no way to cool food fast enough to avoid food poisoning due to bacterial growth.

The way to keep food safe for long times, is to keep it hot enough so that bacteria can’t grow (above 60-65C). At those temperatures, food is safe for days (but the food gets mushy after too long). If you are feeding hundreds of people over hours, you must keep it hot all along, there’s no other way. And for that you need an induction cooker, a jacketed pot, or a way to control temperature to avoid scorching.

For more info, see Hazard analysis and critical control points - Wikipedia

…and now I’m signing off

Awesome :clap: thank you for your invaluable insights. The thing is, we can rather easily use SFOC to run an induction heater coil, it’s basic MOSFET switching. So I will argue we are within SFOC topic here, although it is a rather alternative use-case.

I agree with your point about the double helix blades being a pain to clean. One could consider a much simpler stirring design, one that would be easy to rinse off using the dishwasher rotating water-propeller approach.

Perhaps something like this;

30mm Ø bend tupe helix. Reversed inner helix to circulate the mush.

The idea is to mix the matter, while using induction heat, slowly. And since it is made of round pipes, it should be possible to clean it well using some sprinkler system in the top (like a dishwasher).

The round shape minimises fricktion, so less torque is needed.

This is the NEMA34 in comparison. It does look tiny…

This seems like a quite difficult shape to fabricate…

Yes, it seams that way, but actually it is not as difficult as it seams. The difficult part is building the contraption for bending the tube. Once the tubes are bend, it’s like a walk in the park welding everything together. Maybe the diameter can change some places to facilitate a swifter assembly.

Don’t ask me how. It’s some kind of magic :magic_wand:

You do have a point regarding not welding the two double-helixes to the same support. By offsetting the inner double-helix, it becomes somewhat easier to first weld the inner using separate support beams and later the outer double-helix. Perhaps the center beam holes can be laser cut, for faster machine fab.

Regarding the bending of the tubes, I just spoke with a local company and they should be able to fab the helix using 30mm Ø tubes. Maybe 20mm Ø is enough, not sure about that, but it must be cheaper.

Perhaps we don´t need to weld the spiral/helix to the support rod. Maybe some kind of food-grade connector can be molded. Just, I don´t like the idea of small bolts in my soup :stuck_out_tongue:

Regarding the rpm vs. torque vs. gearing etc. I’m starting to think, that it would be nice to have the option at least to really make a vortex in the barrel, in some occasions. On occasions, I think, it is a good thing to mix the content up. Also, in my experience, part of making lentil-soup delicious is smashing the legumes somewhat, to get that creaminess mixed with the spices, oil and herbs :herb: aka whirlpool, eddy, torrent.