How does a mixer grinder work?
A motor that spins 20,000 times a minute, blades whose tips hit 200 km/h, and ribs that stop your chutney riding round the jar. Take India's favourite kitchen machine apart in 3D.
▶ Play with it · Read the 60-second explainer · Watch the 40-second video
- A fast motor under a jar of blades. A mixer grinder is a heavy base holding an upright electric motor, with a jar on top. The jar's blades sit on a short shaft through a sealed bushing, and a rubber coupler links them to the motor when you set the jar down. A speed switch, a cooling fan, suction feet and an overload switch complete it.
- A motor that runs on AC because both halves flip. The universal motor sends the same current through its field coils and, via carbon brushes and a commutator, through its spinning armature. When the mains flips 100 times a second, both magnets flip together, so the push never changes direction. It races at about 20,000 rpm empty and slows under load while drawing more current.
- Tiny blades, racing-car tip speed. The tip speed of a blade is v = ω × r. At 18,000 rpm a tip 3 cm from the centre moves at about 57 m/s, roughly 200 km/h. The blades smash and shear the food, and bits get smaller fast at first, then more slowly, since each step finer needs more energy.
- Ribs stop the whole load spinning. On its own, the load swirls round with the blade, forming a vortex, and the blade slips through food that is already moving. Ribs on the jar wall break the swirl into an up-and-down loop, so food keeps falling back into the blades. A little water, or pulse mode, helps thick loads flow back.
- Every watt ends up as heat. Current heats the windings, and the work done on the food heats the food: Q = P × t. A heavy load draws more current, and heating grows with current squared, so mixers are rated for short runs. A bimetal overload switch opens if the windings get too hot, and you reset it under the base.
- A gram of imbalance shakes it hard. A lump spinning with the blade pulls on the machine with F = m r ω². One gram at the blade tip at 17,000 rpm pulls with about 110 N, more than three times the mixer's weight, so it walks. Suction feet, a secure lid and the max line keep it safe.
| Term | Meaning |
|---|---|
| Universal motor | A series-wound motor with brushes and a commutator that runs on AC or DC. It is small, light and very fast. |
| Commutator | A ring of copper bars on the motor shaft. The carbon brushes touch different bars as it turns, switching the armature coils. |
| Back-voltage | The voltage a spinning armature makes against the mains. The faster it spins, the less current can flow. |
| Tip speed | How fast the end of a blade moves: v = ω × r, turning speed times radius. |
| Vortex | A swirling mass of liquid whose surface dips in the middle and rises at the edge. |
| Flow breakers | Ribs on the inside of a jar that stop the load swirling round with the blade. |
| Overload protector | A heat-sensitive bimetal switch that cuts the motor's power when its windings get too hot. |
| Duty cycle | How long a machine may run before it must rest, such as 30 seconds on and one minute off. |
| Unbalance | Mass that is not spread evenly round a spinning part, so it pulls the machine round in a circle. |
11,000 years from a stone rubbed on a stone to the three-jar mixie whirring in nearly every Indian kitchen.
- 2500 BCE · The sil-batta (People of the Indus Valley civilisation, Indus Valley (today India and Pakistan))
- 500 BCE · The stone starts to spin (Iron Age people of the Iberian Peninsula, North-east Iberian Peninsula (today Spain))
- 1905 · A tiny motor that spins very fast (Chester Beach, Racine, Wisconsin, USA)
- 1922 · Blades at the bottom of the jar (Stephen J. Poplawski, Racine, Wisconsin, USA)
- 1937 · The Waring Blendor (Fred Osius and Fred Waring, Chicago and New York, USA)
- 1955 · The electric wet grinder (P. Sabapathy, Coimbatore, Tamil Nadu)
- 1963 · Sumeet: a mixie made for Indian food (Satya Prakash Mathur and Madhuri Mathur, Mumbai, Maharashtra)
- 2006 · The limit rises to 750 watts (Bureau of Indian Standards, New Delhi)
The full story, with 29 moments, charts, people and 30 sources: glassbox.how/e/mixerclear/history. The data lives in history.json.
Made with the Glassbox studio from this box's storyboard (window.glassbox.director). Free to reuse under CC BY 4.0.
| File | What | Size |
|---|---|---|
glassbox/reel.mp4 |
Reel / Short, with captions and soundtrack | 1080×1920 |
glassbox/video.mp4 |
YouTube video, with captions and soundtrack | 1920×1080 |
glassbox/slide-1…10.jpg |
Instagram carousel | 1080×1350 |
glassbox/thumb.jpg |
YouTube thumbnail | 1280×720 |
glassbox/cover.jpg |
Share card and repo social preview | 1200×630 |
glassbox/history-reel.mp4 |
“History in 10 moments” Reel / Short | 1080×1920 |
glassbox/history-slide-*.jpg |
History carousel | 1080×1350 |
glassbox/post.json |
Post copy and schedule used by the publish kit |
This box has no accounts and no ads, and it ships its own fonts and libraries. When you run it yourself it sends nothing anywhere. On glassbox.how, the site's /bar.js also loads Glassbox's analytics: Google Analytics to count visits (it asks first in the EU, UK and Switzerland, and stays off when your browser sends Global Privacy Control or Do Not Track) and ClickTrust to detect bots.
It remembers a few things in your own browser only, and never sends them anywhere:
| Browser storage key | What it holds |
|---|---|
mixerclear.v1 |
Which chapters you have opened, your best quiz scores, and sound on or off. |
Exactly what each one sees is at glassbox.how/privacy.
- Code: MIT. Use it, change it, ship it.
- Explanations, text, images and videos (
glassbox.json,glassbox/): CC BY 4.0. Credit “Glassbox, glassbox.how/e/mixerclear”. - Third-party parts keep their own licences: three.js (MIT), Geist, Instrument Serif (SIL OFL 1.1).
- The Glassbox name and logo aren't covered by either licence. See the terms.
Found a mistake? Open an issue. Corrections happen in public.
It's plain HTML, CSS and JavaScript. No build step and no dependencies. Run locally, it contacts no other website.
python3 -m http.server 8000Three.js and the fonts ship in vendor/ and fonts/, so it also works offline.
Then open http://localhost:8000.
| File | What |
|---|---|
index.html, css/app.css |
The page and its styles |
js/app.js, js/stage.js, js/ui.js, js/kit.js |
The shared Glassbox 3D engine: chapters, 3D stage, controls, quiz, video director |
js/chapters/*.js |
One file per chapter: the 3D model, controls, text, key terms, quiz and video scenes |
js/mixer.js |
The mixer models and physics shared by the chapters: the universal motor's speed, current and power, the three jars and blades, the base unit, grinding (Rittinger's law) and flow tracers in the jar |
glassbox.json |
Title, question, explainer beats, key terms, browser storage and credits shown on glassbox.how |
reel in each chapter |
The storyboard the Glassbox studio records into short videos |
glassbox/ |
The published video, slides, thumbnail and post copy |
fonts/, vendor/three/ |
Self-hosted Geist and Instrument Serif (SIL OFL 1.1) and three.js (MIT) |