Theme 3: Evans

Welcome to — your final invention.

Franklin gave you circuits and sensors. Bushnell gave you sub-systems and specialization. This week you put both to work on the most ambitious idea in the workshop: moving stuff without ever touching it.

By the end of the week, your pair owns one machine in a fully working automated mill. The class together has the whole flow.

Theme 3 of 3

Oliver Evans — The Automated Mill

In 1785, a 30-year-old self-taught engineer in Delaware named Oliver Evans did something nobody on Earth had done before: he built a factory that didn't need humans. His flour mill ran on five connected machines — a bucket elevator, a horizontal conveyor, a hopper, a grinder, and a sifter — that together could take whole grain in at one end and produce sacks of finished flour at the other, without a single person touching the grain. One operator could run the whole thing.

He patented it in 1790 — only the third U.S. patent ever issued, signed by George Washington himself. The American flour industry adopted his design and exported flour across the world. Evans went on to design a high-pressure steam engine and predicted, decades early, that one day there would be steam-powered carriages running on iron roads across the country. People mocked him. They were wrong.

This week, you build a piece of his mill.

🌾 Flow

Today's challenge starts simple and gets hard fast.

History spotlight

Before Evans's mill, every step of grinding grain into flour required workers physically moving grain from one machine to the next — carrying sacks, shoveling, spreading flour out to dry. Hot, dirty, exhausting work. Evans saw that if you could just connect the machines so grain flowed automatically from one to the next, you'd save the muscle for something else. Same idea powers every factory on Earth today.

Instructions

Part I: The challenge

The mission: Move 30 dried beans from the cup at one end of your table to the cup at the other end. You cannot touch the beans with any part of your body. You have 25 minutes. Build whatever you need to from the materials at your table.

Materials at your table

Cardboard (sheets, strips, scraps)
Dowels and craft sticks
String and rubber bands
Small paper cups
Tape and scissors
2 cups + 30 dried beans (the cargo)

No rules about how — gravity, paddles, conveyors, drops, slides, whatever you can think of. Just two rules: no touching the beans, and they have to end up in the destination cup.

Instructions

Part II: Run it

When time's up, run your contraption. Count the beans that make it to the destination cup. Note the ones that fly off, get stuck, or never move.

In your 📓 Inventor's Notebook, record: how many beans made it, how many didn't, where the failures happened.

Instructions

Part III: The lesson

Walk around. Look at what other pairs built. Steal what worked. Notice what didn't.

Talk with your pair:

What's actually hard about moving material without hands?
If you had to build a real factory to do this, what would you specialize in?
Where in your contraption did beans get stuck? What part of a real factory would have the same problem?

Tomorrow, every pair picks one piece of Evans's mill to master.

🌾 Mill Stations

Evans's mill had five machines. Each one did one job. Together, no humans needed.

Today you pick which one to own.

Instructions

Part I: Pick your machine

Read all five. Pick one with your pair.

🪣 Bucket Elevator

Your job: lift beans from a low place to a high place. A loop of buckets on a belt that turns when you crank it. Beans go up.

Real-world: grain silos, parking structures, baggage handling. Materials: string belt, small paper cups (the buckets), dowels for axles.

🛤️ Conveyor

Your job: move beans horizontally along a flat or angled path. Belt, slide, or rolling system — beans cross the distance under their own momentum or your crank's power.

Real-world: airport baggage, factory floors, grocery checkouts. Materials: cardboard chute, dowels, string belt, paddle wheels.

🌾 Hopper

Your job: hold a pile of beans and release them at a controlled rate. A funnel with a gate. Open the gate a little, beans trickle. Open it more, beans pour. The point is precision.

Real-world: salt shaker, gumball machine, gravel pit dispensers. Materials: paper cup with a hole, sliding gate, funnel shape.

⚙️ Grinder / Sifter

Your job: change the beans on their way through. Crush them, sift them, separate small from large. The machine processes — input on one side, transformed output on the other.

Real-world: flour mills, kitchen sifters, recycling plants. Materials: screen mesh, cardboard frame, hand-crank crusher mechanism.

🎯 Sorter

Your job: separate beans into categories — big ones one way, small ones another. Or "good" beans into one bin, "bad" ones (sticks, husks, mystery objects) into another. Quality control.

Real-world: trash sorters, mining equipment, agricultural sorting machines. Materials: tilted ramps, sized holes, gravity-based routing.

Instructions

Part II: Plan in your notebook

Open your 📓 Inventor's Notebook to the Evans Specialization Role Page. Fill it in.

You know the drill from Bushnell. One job, materials needed, what success looks like, biggest worry, backup plan. Be specific.

Instructions

Part III: Start building

Head to your specialty's materials table. Grab what you need. Start your machine.

By end of class, every machine should be able to do its one job at least once. Not perfectly. Once. That's the bar. You have the rest of the week to make it reliable, fast, and connected to the others.

🌾 Test & Combine

Today your machine has to work reliably by itself — and then you find out what happens when you try to hook it to the one next to you.

Instructions

Part I: Solo run

Run your machine through 30 beans, three times.

In your 📓 Inventor's Notebook, record for each run:

Beans that made it through: ___ / 30
Beans that jammed: ___
Beans that flew off, dropped, or vanished: ___
Time to process all 30: ___ seconds

If your numbers are bad — fix the worst failure first, run again. Iterate.

Instructions

Part II: Find a partner

Look around the room. Find a pair whose machine could feed yours, or that yours could feed. Some natural pairings:

Hopper → Conveyor — hopper drops beans onto the conveyor's start
Bucket Elevator → Hopper — elevator dumps beans into hopper for controlled release
Conveyor → Grinder — conveyor delivers beans into the grinder's intake
Grinder → Sorter — sorter separates the processed output
Sorter → Bucket Elevator — elevator moves sorted product to the next stage

Find one. Make a plan. The two of your machines together should handle a full 30-bean batch.

Instructions

Part III: Combined test

Set up your two machines side-by-side or end-to-end. Feed 30 beans through the combined system. Time it. Count successes and failures.

The handoff is the hard part. Beans get stuck where one machine ends and the next begins. Talk to your partner pair — adjust the angle, the height, the spacing. Real factories spend more engineering on the *connections* than on the machines themselves.

In your 📓 Inventor's Notebook, note: how did the combined test compare to your solo run? Better, worse, weirder?

🌾 Sensor Day

Evans's real mill had no electronic sensors — the operator just watched. Today's factories have hundreds. Every modern mill knows in real time how full each tank is, how fast each conveyor is moving, when a part is jammed. You're going to bring your mill into the 21st century.

Instructions

Part I: Pick what to detect

Use your Makey Makey to detect one event in your machine's operation. Possibilities by specialty:

Bucket Elevator: a bean drops into the receiving cup (each one fires a tone — bean counter)
Conveyor: the belt is moving (a paddle wheel closes a foil contact each rotation)
Hopper: the hopper is empty (the bottom is no longer covered by beans — circuit opens)
Grinder / Sifter: a processed bean falls through the screen (each one fires a tone)
Sorter: a bean is routed into the "good" bin vs. the "reject" bin (two different sounds)

These are starting points. If you've got a better idea for your specialty, run with it. The Makey Makey must stay dry — no water, no beans inside it.

Instructions

Part II: Design and build

The basics:

Two pieces of foil that touch when the event happens and don't touch otherwise.
One alligator clip to each foil piece, run to SPACE and EARTH on the Makey Makey.
Scratch fires a sound (or counts on screen, or whatever you design).

A bean as a "switch": a single dried bean falling onto two foil contacts can momentarily bridge them — closing the circuit for a fraction of a second. That's enough to trigger Scratch. Each bean = one trigger. That's how a bean counter works.

In your 📓 Inventor's Notebook, sketch your sensor design before building. What event? What two pieces touch?

Instructions

Part III: Run the mill with the sensor live

Connect the sensor to the running machine. Send beans through. Listen for the sensor firing. Is it firing every time it should? Is it firing when it shouldn't?

Adjust. Test again. Lock it in.

🌾 Mill Run

Final session of Evans. Your machine is built. Your sensor is wired. Time to run it for the room.

Instructions

Part I: Final tune-up

Set up your machine. Run 30 beans through, sensor live, three times. Anything broken, fix now. Anything inconsistent, lock in.

Instructions

Part II: Pair showcase — 2 minutes each

When it's your turn, do all of this:

Name your machine and announce your specialty.
Run a full batch of beans through it, sensor firing live.
Tell the room your throughput — how many beans per minute, how reliable.
Answer: what would you change with another week?

Instructions

Part III: Stretch — the class-wide mill

If there's time: chain every working machine in the room into a single continuous flow. Hopper → Elevator → Conveyor → Grinder → Sorter. Feed beans in one end. See how many make it through the whole class-wide system to the final bin.

It will probably fail. Real factories took Evans years to get working. But the moment a bean makes it through three or four connected stations without anyone touching it — that's the moment you'll feel what 1785 felt like.

In your 📓 Inventor's Notebook, finish the Evans theme wrap and the full-workshop reflection. You've got one session left after this.

That's Evans. That's the workshop. Three inventions, fifteen builds, a notebook of real engineering work. Next session: the Showcase. Family, staff, and whoever else you want to invite gets to see what you made.

Career Connection

Everything you did this week is the foundation of industrial engineering — the field that designs how factories, warehouses, hospitals, and supply chains actually work. Amazon's fulfillment centers, Tesla's gigafactories, every modern food processing plant — all of them are descendants of Evans's mill. The job pays well and you don't need an Ivy League degree; state schools have some of the best industrial engineering programs in the country.

The Makey Makey sensor work connects to mechatronics and automation engineering — the people who design self-driving cars, robotic assembly lines, and the kind of "lights-out factory" where humans only visit to fix things. Mechatronics is one of the fastest-growing engineering fields right now.

Paths in: industrial engineering, mechanical engineering, mechatronics, supply chain management, operations research. Two-year mechatronics programs at community colleges get you into entry-level technician jobs in 18 months — often with companies that pay your tuition for a four-year degree on top of it.