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Wind-up mug mixer (not for real use)
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This powerful wind-up mug mixer is a gag. It can blend cream into your coffee in a single pass, but do NOT drink the stuff!
About this creation
WARNING! Do NOT consume drinks or foods mixed with this MOC! ABS plastics are NOT FDA-approved for contact with hot food, and some ABS plastics are not approved for contact with ANY food. The mixing of hot coffee described here is intended as a gag and NOT a suggestion for real-life use.

Please feel free to look over the images and skip the verbiage.

Too brain-dead to work a spoon after that LEGOŽ all-nighter? Well, a simple pull of this mug mixer's trigger can get that coffee fix stirred faster than you can mumble "Must...get...caffeine!"



Just remember: If you overwind it, you're liable to end up wearing the coffee instead of drinking it. (Read "tea" here if you prefer.)



Of all the attachments I've tried, this 5.5L 3-blade propeller (4617) is the best at mixing coffee and cream. More importantly, it can't fly apart at high speed in air.



In the mug shown, this impeller has a safety rating of 7, meaning that liquid will reliably stay in mug with 7 half-turns of the winder, but not with 8.



Purist alert: To use this prop as an impeller, you have to wrap the blue axle-pin at its center with a little Scotch tape to keep it from slipping.

Now you might be thinking that a spoon would be a lot simpler and cheaper and safer to use half-awake, and you'd probably be right. But what fun would that be??

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Features

This powerful wind-up mixer comes loaded with features designed for easy use while half-asleep.



∨ Reversible grip: The yellow grip and orange winder handle are easily configured for either clockwise or counter-clockwise mixing as seen from above. On this page, the mixer's set up for the latter, which makes it easier to wind with the right hand.



∨ Motor: The powerful 6x5x3 pull-back motor (12787c01) doesn't need full power (17-18 half-turns) to mix a mug in a single pass.



Attachments: Attachment possibilities abound and are by no means limited to stirring coffee, but some are safer and more effective than others. All the examples in the next 2 photos hold together at high speed.

As mentioned, the yellow 3-blade prop at bottom left here is the best bet for most mugs. The props in the top row have the wrong handedness and tend to splash.



Impellers without angled blades don't mix very effectively and also tend to be messy, but some work well enough in small mugs.



∨ Winding ratchet: A simple trigger-operated ratchet allows single-handed winding.



∨ Safety latch: The trigger flips up to reduce the likelihood of accidental release or latches down below the ratchet plane (not shown) to eliminate this possibility entirely.



∨ Rating indicator: Two numbered 1x1 tiles on the grip help you remember the rating of your favorite morning mug-attachment combo.



∨ Knurled chuck: The ridges on the orange chuck make it easier to pull out attachments by their shafts.



∨ Drainage foot: The motor takes on little if any liquid during normal mixing. But just in case, a cross-bar (bottom right) promotes drainage of any liquid present by keeping the grip horizontal while resting chuck-down with the shaft removed.



∨ Built-in back-off warning: The orange growly face on the trigger warns others in the room to leave you alone. This comes in handy when you lack the firing neurons to wave them off yourself.



Visibility: The high-visibility orange and yellow color scheme makes it easy for the groggy user to locate the mixer and attachments and determine which end is up with eyes barely open.

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Safe operation

WARNING! Do NOT consume drinks or foods mixed with this MOC! ABS plastics are NOT FDA-approved for contact with hot food, and some ABS plastics are not approved for contact with ANY food. The mixing of hot coffee described here is intended as a gag and NOT a suggestion for real-life use.

WARNING! This mixer is not for young children. It has more than enough power to send hot liquid flying or turn susceptible attachments into dangerous shrapnel when triggered in air.

Containment: Remember, every mug-attachment combo has a "safety rating" equal to the maximum number of half-turns you can wind the mixer and still keep every drop of liquid in the mug every time.

In the industrial mixing biz, this requirement is known as "containment". In a LEGOŽ mug mixer, the goal is get a thorough mix with reliable containment in a single pass.

To stay safe while half-asleep, do this first while wide awake: Determine the rating for your favorite morning mug-attachment combo using cold water. If any water leaves the mug, use fewer half-turns, a deeper mug and longer shaft, a less aggressive attachment, or a weaker motor. Then repeat.



Once you have reliable containment, record the rating on the rating indicator (here showing "04"). If you change the mug, attachment, or both, record the new rating before using the mixer in your morning stupor.

∨ Test mug: Unless otherwise noted, any ratings quoted here apply only to the larger "test mug" on the left when filled as shown. Ratings for lower fill levels or shorter or narrower mugs will generally be lower.



For example, with the 5.5L 3-blade impeller mounted, the ratings above are from left to right 5, 7, and 11.

Centrifugal soundness: Trust me, impellers built up from parts can easily fly apart at even 50% power in air -- say, after an accidental pull of the trigger.

For example, these red attachments can't take the centrifugal stresses generated at full power, but their reinforced orange and yellow counterparts can.



WARNING! Always wear eye protection when testing high-speed LEGOŽ rotating machinery and keep valuables and bystanders (including pets) a safe distance away. Really.

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Optional: Attachments and flows

When you wake up desperate for caffeine and in no mood for spills, you want a mixer that can blend your coffee and cream or sugar into a uniform liquid in a single pass without mishap. My goal was to get complete mixing of the cream in one shot while minimizing the number of additional passes needed to get the sugar fully dissolved.



Problem is, cream and sugar tend to drop to the bottom of a mug without much mixing. As seen at 0:19, 1:33, and especially 2:22 in the 1st video, that leaves a coffee-rich upper layer and a cream- or sugar-rich lower layer with little incentive to mix further except by slow diffusion. Having a total liquid depth greater than the mug's inner diameter only compounds the problem.

Turns out that the best way to force these layers to mix is with a turbulent downflow capable of displacing the lower layer laterally and then upward. Once the liquid column has been substantially overturned, residual small-scale turbulence can finish the job -- at least for cream.

Upflows are less effective at overturning the liquid column and much more likely to threaten containment via "fountaining". Splashing then follows as the erupted liquid falls back into the mug or onto the table.

Even less effective and more accident-prone is "swirl" -- the whirlpool-like horizontal flow component circling the inside of the mug (e.g., at 0:49 in the 1st video). This more laminar motion accomplishes little in the way of mixing but can easily push liquid up and over the lip of the mug via centrifugal force.

Swirl is unavoidable in a mug mixer, but some attachments have better (higher) downflow/swirl ratios than others. In practice, swirl is usually the limiting factor in mug-attachment safety ratings.

Impellers: Technically, a mug mixer attachment is an agitator consisting of an impeller rotating on a motor-driven vertical shaft. The agitators on this MOCpage differ only in impeller design, as they all use 9L axles for shafts.



The impeller's role here is to receive a certain amount of mechanical energy from the motor via the shaft and translate it into an effective mixing flow that doesn't threaten containment.

To get the desired downflow with the mixer configured as shown, you need an impeller made from a right-handed LEGOŽ prop.1

The right-handed props are on the bottom row here. The yellow 5.5L 3-blade (4617) at far left has the highest downflow/swirl ratio of any mug-sized impeller I've found, and it can't fly apart. Most mugs are too small for the two 9L props on the right, but they probably produce even more downflow.



The left-handed props in the top row, on the other hand, have dominantly upward outflows.

Unlike the props, the inefficient impellers below have mostly horizontal outflows with very low downflow/swirl ratios. The secondary vertical flows they produce are generally too chaotic to get much vertical mixing done.



Of these, the 3-armed cage impeller near the center and the 36-tooth gear impeller near bottom left are the most efficient, but that's not saying much. Smaller gears do very little.

Unfortunately, most of the centrifugally sound mug-sized LEGOŽ impellers one might devise produce swirl and little else, and that's true of nearly every impeller in the last photo.



∨ Impeller flow patterns visualized: The video below uses red glitter to trace the flows produced by 4 very different impeller designs, starting and ending with the preferred 5.5L 3-blade prop.



At full power, the 5.5L 3-blade impeller ultimately lifts tracer ~90% of the way to the top of the liquid column in a single pass. Meanwhile, swirl raises the liquid surface from the 900 ml level to a little below the 1,000 ml level.



This large paddle-style impeller, on the other hand, does just the opposite: It routinely generates a strong swirl in the upper third of the tank without lifting tracer above the 400 ml level. Meanwhile, the swirl raises the liquid surface to above the 1,100 ml level. This is the worst of the downflow/swirl ratios tested.



Any more than 3 half-turns of this impeller in the test mug, and swirl sends coffee over the top. Just don't count on one-shot mixing at such a low power level.

Cage impellers are often used to mix paint. This one generates lots of swirl, but tracer never leaves the bottom 1/3 of the tank.



This 36-tooth gear impeller looks aggressive but generates even less vertical mixing.



Other factors affecting mixing efficiency and containment include (i) the impeller/mug diameter ratio, (ii) the shape of the mug's interior, (iii) liquid depth, (iv) impeller geometry and immersion depth, (v) agitator angle and lateral offset WRT the mug's vertical centerline, and of course (vi) the magnitude and duration of the motor power applied.

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Optional: Wind-up motor options

Spring-driven LEGOŽ motors (aka wind-ups or pull-backs) have varied widely in size, shape, torque, and angular speed over the years. Among those capable of driving a Technic cross-axle, some are too powerful to wind all the way with the most agressive attachments, while others are too wimpy for any attachment.

The mug mixer presented here uses TLG's latest 6x5x3 pull-back (12787c01, 2013). When fully wound to 17-18 half-turns with the wrong attachment-mug combo, it can empty the mug in a heartbeat.




Same 12787c01 pull-back mounted in the reversible flying rotor launcher from which the mug mixer evolved. The fact that it can propel the rotor shown to an altitude of 15 m gives you an idea of its power and speed.

The weakest axle-compatible wind-up (61100c01, 2008) offers a convenient built-in ratchet with push-button release in a 2x4x2.33 studded package. However, speed and torque are totally inadequate for most purposes, including mug mixer use.



The rest of the axle-compatible wind-ups generally fall between these extremes. Most are probably workable with the right attachment and mug.

This compact wind-up top starter uses an older 7x5x3 pull-back (motor6, 2002) with a form factor similar to that of 12787c01.




It's just as powerful as 12787c01 but becomes fully wound at only 9 half-turns instead of 17-18. I like that in a top starter.

This simple mug mixer uses a 10x8x4 split-arm pull-back (motor8, 2003) with an attachment just agressive enough to use in our test mug fully wound (~10 half-turns).



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Specifications as shown

Overall dimensions:142x142x66 mm (LxWxH) including attachment
Mass:101 g with attachment
Grip configuration:Optimized for winding with right hand
Winding direction:Clockwise as seen from above
Mixing direction:Counter-clockwise
Motor:6x5x3 pull-back (12787c01)
Shaft:9L axle
Preferred impeller:Right-handed 5.5L 3-blade propeller (4617)
Modified LEGOŽ parts:Impeller axle-pin taped to prevent slip
Non-LEGOŽ parts:None
Credits:Original MOC
See also:Wind-up biconic top starter, wind-up flying rotor launcher

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Footnotes

1 To determine the handedness of any propeller, lay it down on a flat surface with one blade at 12 o'clock. Call this the "index blade".

If the right edge of the index blade is closer to the table, the prop is right-handed. If the prop then rotates so as to turn the index blade to the right, the outflow will be toward the viewer.

Conversely, if the left edge of the index blade is closer to the table, the prop is left-handed. If the prop then rotates so as to turn the index blade to the left, the outflow will again be toward the viewer.

Try it with the propellers below. Hint: One row is right-handed and the other left-handed.



If both edges of the index blade are equidistant from the table, as in most of the cases below, the outflow will be mainly radial or circumferential rather than axial, and no useful thrust will be generated.



Many so-called "propellers" and "fans" in the LEGOŽ realm come very close to this description. They're decorative at best.
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Comments

 I made it 
  June 13, 2017
Quoting Family Vuurzoon Cool! That is a completly different application for Lego pull back motors :) Cheers,
Thanks! Pull-backs have a lot of untapped potential. I can easily see the Family Vuurzoon exploiting it.
 I like it 
  June 12, 2017
Cool! That is a completly different application for Lego pull back motors :) Cheers,
 I made it 
  May 15, 2017
Quoting Oliver Becker Highly recommended to every barista all over the world to get a perfect latte macciato, my friend! Then they call it latte macchinismo, I believe... ;)
Ha! Good one, Oliver! Unfortunately, they might also call it latte toxicato if LEGO ABS really does leave evil humors behind in hot water.
 I like it 
  May 15, 2017
Highly recommended to every barista all over the world to get a perfect latte macciato, my friend! Then they call it latte macchinismo, I believe... ;)
 I made it 
  May 15, 2017
Quoting Nils O. That's some freaking cool Lego engineering! Great job! :-))
Thanks, Nils!
 I like it 
  May 15, 2017
That's some freaking cool Lego engineering! Great job! :-))
 I made it 
  May 14, 2017
Quoting The Actionfigure A funny idea! I want one! :)
Thank you! Easy to make. The actual risk in drinking hot coffee stirred by this mug mixer will probably never be known to the public -- in part because TLG uses proprietary ABS. So probably better to err on the side of caution. That said, I still plan to keep mine around, at least as a gag to pull on company. I just won't let 'em drink the stuff.
 I like it 
  May 13, 2017
A funny idea! I want one! :)
 I made it 
  May 13, 2017
Quoting adam thelegofan rutland awesome idea!:D
Thanks, Adam!
 I like it 
  May 13, 2017
awesome idea!:D
 I made it 
  May 10, 2017
WARNING! Do NOT consume drinks or foods mixed with this MOC! ABS plastics are NOT FDA-approved for contact with hot food, and some ABS plastics are not approved for contact with ANY food. The mixing of hot coffee described here is intended as a gag and NOT a suggestion for real-life use.
 I made it 
  May 10, 2017
Quoting Nirds forprez I like the little caricature in Lego bricks at the beginning. Little question though.....(geez is my wife's worldview really seeping in that much into my own?) is..... Is it safe to put ABS into hot liquids? Plastic and human ingestion, even in tiny amounts, never really mix well. I honestly don't know..... and based on my wife's incessant complaining did away with http://www.moc-pages.com/moc.php/413268
Alas, for better or worse, wives have a way of getting into your head. Rats, didn't think of the food safety angle! According to the FDA, there is such a thing as food-grade ABS, but only for room temperature and refrigerator storage purposes, not for hot food. The main issue appears to be potential leaching of unbound acrylonitride. Since we all know that LEGO ends up in mouths one way or another, and since TLG exhaustively tests its parts for toxicity, it's likely that their proprietary ABS qualifies as food-grade. In that case, the mixer and your tumbler would at least be safe for cold drinks. I'll be plastering a warning across the top of the page immediately. Then I'll try to rewrite it, and if that doesn't seem enough, I'll take it down.
 I like it 
  May 10, 2017
I like the little caricature in Lego bricks at the beginning. Little question though.....(geez is my wife's worldview really seeping in that much into my own?) is..... Is it safe to put ABS into hot liquids? Plastic and human ingestion, even in tiny amounts, never really mix well. I honestly don't know..... and based on my wife's incessant complaining did away with http://www.moc-pages.com/moc.php/413268
  May 9, 2017
Awesome! My granddad was mechanical engineer. He oversaw the building of bombs for the government :P Very cool that you do STEM-y stuff with Legos.
 I made it 
  May 9, 2017
Quoting VAkkron ™ This is awesome! Very creative idea, what a cool and inspirational machine.
Many thanks, VAkkron! Finding new uses for these wind-up motors all the time.
 I like it 
  May 9, 2017
This is awesome! Very creative idea, what a cool and inspirational machine.
 I made it 
  May 9, 2017
Quoting Jonathan Demers Another excellent, ingenious build Jeremy! It was fun learning how it works, instead of just looking at it. The only question I have is how do you clean it?
Thanks, Jonathan! Stirring soapy water at full power a few times seems to clean the impeller and shaft pretty well. Since these parts are also easy to disassemble and soak, mixing largely water-soluble substances seems pretty safe, but I'd think twice about oily or greasy stuff. Leaving the yellow prop in coffee too long stains it, but it's a cheap and plentiful part. And if you use a black one, you'll never notice.
 I made it 
  May 9, 2017
Quoting Toa Whero Are you a engineer, or something like that? Sorry, probably seems like a pretty random question, but from the way you talk about you MOCs, I thought you might be an engineer.
Fair question and good guess. I like my LEGO with a big dose of STEM (science, technology, engineering, and math) -- partly because those things are life-long passions I can express through LEGO. It helps that I've trained and worked in scientific fields overlapping quite a bit with mechanical engineering and fluid dynamics.
 I like it 
  May 9, 2017
Another excellent, ingenious build Jeremy! It was fun learning how it works, instead of just looking at it. The only question I have is how do you clean it?
  May 9, 2017
Are you a engineer, or something like that? Sorry, probably seems like a pretty random question, but from the way you talk about you MOCs, I thought you might be an engineer.
 I made it 
  May 9, 2017
Quoting Alex Rode Cool and practicable - so much more than a toy!
Thanks, Alex! Yes, in this case, drug paraphernalia.
 I like it 
  May 9, 2017
Cool and practicable - so much more than a toy!
 I made it 
  May 9, 2017
Quoting Michael P I'm sorry, I meant that you could watch YouTube videos on how to dismantle an espresso machine so you can build your own :) Btw, your videos are excellent!
Thanks again! Duh, now I get it! You're not going to let me off the hook on that working LEGO espresso machine, are you?
 I made it 
  May 9, 2017
Quoting Sven ;o) And another very well crafted little helper made of Lego ;) Great work my friend as usual from you. The small scene is also very very nice :)
Too kind, Sven! Wish I'd had a groggier-looking minifig on hand. Wanted him bent over the table half-asleep, but minifig legs are too short for that with a minifig-scale table.
 I like it 
  May 9, 2017
I'm sorry, I meant that you could watch YouTube videos on how to dismantle an espresso machine so you can build your own :) Btw, your videos are excellent!
 I made it 
  May 9, 2017
Quoting Michael P Hahaha! I'm sure there's a YouTube video for your reference :)
Thanks, Michael! Not sure I follow the video part. I embedded 2 videos in this MOCpage.
 I made it 
  May 9, 2017
Quoting Doug Hughes Love it!!
Thanks, Doug!
  May 9, 2017
And another very well crafted little helper made of Lego ;) Great work my friend as usual from you. The small scene is also very very nice :)
 I like it 
  May 9, 2017
Hahaha! I'm sure there's a YouTube video for your reference :)
 I like it 
  May 9, 2017
Love it!!
 I made it 
  May 9, 2017
Quoting Michael Parkinson This is awesome Jeremy! Now you need to make a true espresso machine :D Cheers ~Michael
Thanks, Michael! If I took my wife's apart to see how it works and messed it up, I'd be in deep trouble, but hey, what's another consecutive life sentence in the dog house?
 I like it 
  May 9, 2017
This is awesome Jeremy! Now you need to make a true espresso machine :D Cheers ~Michael
 I made it 
  May 9, 2017
Quoting Daniel H. Dang! That is wicked! Awesome work man!
Many thanks, Daniel!
 I like it 
  May 9, 2017
Dang! That is wicked! Awesome work man!
 I made it 
  May 9, 2017
Quoting Choco Taco Wow, that's Awesome! I love it!
Very kind!
 I made it 
  May 9, 2017
Quoting Toa Whero Spoons? What are spoons? :P Great work sir!
Thanks! The spoon's time has come and gone. I mean, it's 2017 already!
 I made it 
  May 9, 2017
Quoting Clayton Marchetti That's cool.
Thanks, Clayton!
 I made it 
  May 9, 2017
Quoting Gabor Pauler Very educational!
Thanks, Gabor! Learned a lot on this one myself. Process engineers worry a lot about industrial mixing efficiency and the hydrodynamics involved, and most of their solutions apply at LEGO scale, too!
 I like it 
  May 9, 2017
Wow, that's Awesome! I love it!
 I like it 
  May 9, 2017
Spoons? What are spoons? :P Great work sir!
 I like it 
  May 9, 2017
That's cool.
 I like it 
  May 9, 2017
Very educational!
 I made it 
  May 9, 2017
Quoting Seaman SPb Ha-ha, LEGO food processor! Cool! :-)
Thanks, Seaman! You know, it might just work as a breakfast processor. With the right attachments, the motor would probably be powerful enough to stir fruit into yogurt or butter and salt into sloppy grits.
 I made it 
  May 9, 2017
Quoting Nick Barrett Who needs spoons when you've got one of these ?
That's the spirit!
 I like it 
  May 9, 2017
Ha-ha, LEGO food processor! Cool! :-)
 I like it 
  May 9, 2017
Who needs spoons when you've got one of these ?
 
By Jeremy McCreary
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LEGO models my own creation MOCpages toys shop Wind-up mug mixer (not for real use)Technic


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