Introduction: Self Stirring Mug Using Lego

I saw this self stirring mug on YouTube and then this friend introduced me to a piece of lab equipment called a magnetic stirrer. So I decided to create a little prototype of both using Lego pieces.

Step 1: What You Will Need

You will need the following pieces (Give or take)

Materials
Tape (Electrical works well)
2 Bar Magnets (or a lot of disc magnets)
(I used the surplus from www.kjmagnetics.com)

Lego Pieces: (if you decide to make it using Lego)
1 9V Motor
1 9V Battery Box
1 Lego Cable
Plates:
1 6 x 8
2 6 x 10
4 1 x 2 (the ones which have the slots to hold a motor)
12 1 x 8
Beams:
4 1 x 2
2 1 x 6
4 1 x 8
6 1 x 10
Gears:
1 Crown Gear 24teeth
2 24 tooth gears
2 8 tooth gears
Some bushings and pins to connect it all

Step 2: Gear Train

The Lego motor spins at roughly 360 rpm which is quite slow so in order to speed this up we utilize a gear train. Below is a picture of the assembly. The end of the gear train is on the upper left and it will be the part that is attached to the spinning magnet bar.

Step 3: Build a Frame

You want to build a frame to support a cup so in this design I built it using Lego pieces. What is important though is that your frame is sturdy enough to hold a cup with liquid and has some clearance for the spinning magnet mechanism. I used a Lego connector that looks like a T shape to attach the magnet onto the gear train. I also used some tape to secure it. When the setup is complete you should be able to place the bar magnet on top and it will lock into place. I chose neodymium magnets because they were strong.

Step 4: Unresolved Issues

There aren't many steps to this because this was a short project and the video explains a lot of the details. If there were any parts that were unclear I would be glad to explain them or append to the instructable.

There were better ways to mix and blend but this one used magnets and Lego and was entertaining to watch. I didn't use this for drinking purposes due to some cleanliness issues but it sure did mix that iced tea well.

I used a plated magnet and to my knowledge it is plated in zinc. Not wanting to drink zinc I planned to cover the magnet in some form of non toxic plastic. In the past using some spray on liquid rubber to waterproof my use drive and I was hoping to find some similar to coat the magnets.

Also if anyone was planning to make this for drinking purposes I would recommend building a specialty cup that has the magnet fixed to the bottom so that it isn't a choke hazard.

Thank you and I hope you enjoyed this Instructable!

Comments

author
conmorse (author)2008-05-16

the metal bar is a magnet though, would there be any chemicals or particles that would mix with the liquid?

author
cooblades (author)conmorse2008-05-16

The metal bar in the video is a magnet. You would have to coat the magnet with a non reactive plastic, or buy it already covered. Chem suppliers have them. Normal magnetic stirrers are hundreds of dollars. Here is a site that offers some examples of what I'm talking about.
http://www.coleparmer.com/catalog/product_index.asp?search=stir+bars&keyword=magnetic+stir+bar&gcid=s18582x088&wt.srch=1

author
Spokehedz (author)cooblades2008-08-28

You can buy the teflon coated-magnets without buying the whole stirrer. Here is a link to a place where they are pretty cheap:

http://www.labdepotinc.com/Category_Details~id~336.aspx

I actually prefer the ovoid (egg) shaped ones, as the bottom of my some of my mugs are not flat in the middle and the other stir bars don't spin as fast. Plus, they are small enough that they work in all sizes of cups.

http://www.labdepotinc.com/Product_Details~id~336~pid~12648.aspx

Teflon is non-reactive (for high acidity drinks like orange juice) as well as highly resistant to heat (coffee) although the magnet doesn't like the hot temperatures... But they are cheap enough and even with abuse they last for years and years.

author
swordchop (author)Spokehedz2015-10-12

really?>:(

author
swordchop (author)2015-10-12

awsome

author
knex_mepalm (author)2010-08-20

I might choke on the magnet, if I made a string and drilled a hole and attached it would it still work?

author
Kaiven (author)2009-07-18

Now I want to make one of these too :( There are too many good instructables that take up my day! :D

author
freezier (author)2009-04-27

ok. so as someone who owns a real hotplate / stirrer, i have one little detail everyone seems to be missing. that bottom magnet that is attached to the motor? Its not a bar magnet. Its a ring magnet. you want a ring that is about 3 inches outside diameter. epoxy it to a metal circle which you attach to a suitable motor. make sure it is centered or bad things will happen.

author
Speedmite (author)2009-03-17

I made this a day or two ago, great instructable! I didn't use exactly called for, but it worked. Problem is with making one of these it that you HAVE TO HAVE the perfect magnets. Most magnets I had were too weak or too bulky. Anther problem with making one is that the legos are hard to balance on a rod, even with adding a T-bar. and conmorse is right. Unless you get a magnet meant for this, magnet particles and possibly paint could get in it. Fun, but impractical.

author
get to da parakeet (author)2008-09-29

ALSOME!!!!!

author
wotot2 (author)2008-07-03

i am confused on how to atach the magnets to the motor assmbley

author
cooblades (author)wotot22008-07-03

I have a T shaped Lego piece attached to the motor shaft. I taped a strong bar magnet to that piece. Its shown in the second and third picture of step 3. Then the red plate is placed over and a freely moving magnet is placed on top. The magnetic attraction of the bottom magnet causes the top one to spin.

author
wotot2 (author)cooblades2008-07-07

thanks

author
James (pseudo-geek) (author)2008-07-03

you made me want to get my legos out again :( and I have no place to put them.

author
Nicolas Jara (author)2008-06-01

I like it.

author
conmorse (author)2008-05-10

Would it still be safe to drink the water?

author
Rokko8652 (author)conmorse2008-05-14

Yes, the only thing that the thing in the cup is is a metal bar, just make sure it is clean

author
Yueh16 (author)2008-05-07

That is really smart.

author
VincentVX73 (author)2007-09-22

I've been thinking about building my own magnetic stirring device for a while now, but I must admit using legos never occurred to me...thanks for the time saving idea! Oh, and good choice on the music, Paul Van Dyk is simply mesmerizing.

author
Negafen (author)2007-07-20

To prevent someone from swallowing the stir rod take a disc shaped magnet and hold it to the bottom of the cup. The indentation that is likely in the cup will hide the magnet, and both magnets should stick in place. If the stir rod isn't a strong enough magnet to hold the second magnet to the bottom of the cup, then use the second magnet to drag the stir rod out of the cup before drinking.

author
thinker (author)Negafen2007-07-22

erm a MUCH easier and better one to do would be simply have an inversed "T" where the "-" part is the magnet and the "|" part is a large piece of metal/plastic, if the magnet is plastic coated so it is non-toxic and the attachment doesnt use toxic chemicals then it should still be drinkable, as the handle is vertically attached (perpendicular) it will be in the centre of the vortex created by the magnet and so will not creating any detrimental effect to its speed and being easy to remove. This also leads to a possibility of making it with larger bottles as you could add fins to the handle to create flow.

author
Negafen (author)thinker2007-08-03

Umm... read my post again, I'm not talking about anythnig that goes in the cup, or gets attached to the bottom. Just something that you can sit there as a quick fix for a mentioned problem in the instructable. I'm talking about after, so your guest doesn't accidentally swallow the rod. Also, it's not my instructable, and I didn't mention the stirring portions of the instructable at all. Also also, adding fins will not help in the slightest. The high rpm is what creates the vortex, add fins and you'll add too much resistance. You'll encounter something known as "spin out" which is when the magnetic coupling is not as strong as the hydraulic resistance, meaning your finned T thing will lethargically lurch around in the cup. Stick with the sciences and you'll encounter actual high speed electronic stirrers, you'll see a total lack of fins on them.

author
cooblades (author)Negafen2007-08-03

I hate to take sides, but negafen is right about spin out. I maxed out my device at around 3000 rpm. The vortex is amazing, it reaches the bottom completely as you could see in the video. It mixed 3 tablespoons of ice tea mix in a few seconds (not that I'm going to drink it). I gave the inversed T idea a shot and the bar is very unstable, sorry thinker :-(. The fins approach I'm not even going to try because at 3000 rpm I know I would lose coupling.

author
thinker (author)cooblades2007-08-20

ahh reet no problemo, when i posted that i wasnt sure whether it would create drag on it or not but now i think about it it does make sense >_< and yeah, i get what you mean about the bar being unstable after i tried my own idea. thanks for readin it tho,

author
lemonie (author)2007-07-20

This is really cool. I've spend so much time using expensive Ika stirrers...

L

http://www.ika.net/ika/home.html

author
ewilhelm (author)2007-07-20

Nice use of stop-action on the lego build part!

author
josh92176 (author)2007-07-20

There was also another version published by g0pher, didn't use lego though ;-)

author
cooblades (author)josh921762007-07-20

cool I will take a looksie

author
dantheflipman (author)2007-07-20

This is really neat, i think I'm going to make this tomorrow, Thanks alot for sharing :D

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