Introduction: Entwined Hearts Cast in Aluminum

Picture of Entwined Hearts Cast in Aluminum

This project was inspired by Kiteman's Entwined Hearts.
I had just finished building a metal casting furnace and needed to make a valentine's day present for my wife. I found his idea and decided to translate it into cast aluminum. I used a technique called lost foam casting which involves pouring molten metal directly on a pattern made out of foam. The foam vaporizes and the metal fills the void creating the casting. I hadn't tried it before but it's supposed to be fast and easy and involves fire. Who doesn't like that?

Step 1: Cutting the Pattern

Picture of Cutting the Pattern

First you need a pattern of what you want to cast.  You will need two hearts.  Mine are about 5" tall and 3/4" thick.   Start with a piece of foam insulation.  You want the pink or blue stuff that they sell at the hardware store. It's possible to use white beadboard but it's crumbly and won't give as good of a resolution.    I cut out my heart patterns on a cnc router (I got the cnc bug from  this excellent instructable: but ended up using plans from  which ended up being a two year diversion) You certainly don't need to use a cnc router to make your pattern.  A saw, knife, file etc. will do just fine.  I cut out the heart in two pieces and glued them together.  Make sure that you add two sprues off the top of the heart.  This is where the aluminum will enter and exit the mold. It took about 20 minutes to cut each piece. The ridges in the pattern are because I cut it out at a low resolution.  I was too impatient to wait longer for a smoother cut and I thought the they looked interesting.  I uploaded the G-code if you want to use my pattern.

Step 2: Preparing to Cast

Picture of Preparing to Cast

 Now that you have your patterns it's time to fire up the foundry.  If you don't have a metal casting set up you can find instructions for building one on this site or there is also an excellent forum/community of backyard metalcasters located here: I found them very helpful in getting me going with an inexpensive (runs off of waste vegetable oil) home-built foundry.  My furnace build is here: 
You can do lost foam casting in a number of ways.  I chose to just bury my pattern in loose sand.  This is the easiest and most immediate method but it gives you a grainy surface from the sand.  I knew I was going to do some finishing to my castings so I didn't mind.  I sifted regular play sand into an old soup pot and buried the first heart up to the top of the sprues.  Then I took a short can with the top and bottom removed and put it around the entry side.  The can acts as a collar to retain the metal and gives you an extra supply to help fill the mold as you are pouring.  You also don't have to be quite as precise as you pour.  

Step 3: Pouring

Picture of Pouring

 I guess it's time to mention that pouring molten metal can be exceedingly dangerous.  Please take the time to research it thoroughly and use appropriate safety gear. You do not want to drop a crucible of liquid metal on your foot.  I don't know what nasty chemicals are released when you vaporize foam but I would strongly recommend  pouring outside and wearing a respirator with organic vapor cartridges in addition to your other safety gear.  Once your furnace is heated up and glowing orange melt some aluminum in the crucible.   Make sure you have plenty melted, you don't want to run out in the middle of a pour.  My hearts took about 1 lb each with the sprues and excess.  Have the pot with your mold on the ground near the furnace and all of your tools ready.  When you pour the casting fill the metal collar and don't stop pouring until you see a puddle of metal coming out the other side.  There will be some smoke and fire but you don't want to hesitate in your pour or the metal can freeze up and the mold won't fill completely.  Wait about 5 minutes after the pour to pull the casting out of the sand.  You want to be sure it's nice and hard.  

Step 4: The Second Pour

Picture of The Second Pour

 After the first casting has cooled enough to handle, cut the sprues off with a hacksaw or sawzall.  Cut the second heart and insert the casting so that they are linked like a chain. Glue the foam heart back together.  As you bury the foam this time float the first casting in the sand parallel to the bottom so that it doesn't touch the pattern.  Then go ahead and cast the second heart the same way you did the first.

Step 5: Finishing

Picture of Finishing

Now it's just a matter of removing the sprues and finishing the surface of the hearts the way you like. I used a saw to cut them off as close to the top of the hearts as I could. Be careful not to cut too much off. Next, I used a grinder to rough shape the tops. I used a file to do the final shaping and to smooth the surface somewhat. I wanted to leave the ridges in the hearts but also have them be smooth enough that they invite you to handle them. Finally, I used 120 grit sandpaper to take out the file marks and 600 grit to get the final finish. This was my first real cnc project and my first casting. I was very pleased with the result and my wife liked her present too.

Like projects?  Check out our site where we chronicle our Mighty Projects on our Mini Farm (AKA our backyard).



Creidhne (author)2012-12-31

Awesome post! Wanted to let you know that this inspired me to do my own version!

spike3579 (author)Creidhne2013-01-01

Hey those came out great! Good work. Thanks for posting a pic.

urbanwoodswalker (author)2010-02-21

Melting any kind of plastic or foam casues carcinogenic vapors.  As a cancer survivor, I feel this is more dangerous then just the molten lead part.  How are you protecting your self, family, pets, etc from the dioxicins? 

.... um... what molten lead? he's using aluminum.

That was a typo. I know he is using aluminum. why is no one concerned about the vapors from the foam? I don't see anything about ventilation or anything. Interesting.

He has a whole paragraph about wearing a respirator. Read before you comment. Please stop trying to "protect" everyone. Most of us are grownups here and are aware of the hazards.

Wow...happy holidays to you too.

Its been my opinion many folks who create art and craft have no idea about toxicities. People usually are quite happy to know. Go spread your cynicism elsewhere. :-(

Are you always this grouchy Mr Grinch?

Not grouchy at all. Just tired of people acting like we all need to be protected from every little bump, scratch or bad smell we might encounter. The part that upsets me the most is that the original author wrote about using a respirator, working outside in good ventilation and you completely ignored him so you could get your comment in about "molten lead". And then when you were called on it, you said you made a "typo".

I accidently said lead instead of aluminum. Ok--it WAS a you never have made one before? I already went over that...why beat a dead horse? I still can't find "a paragraph" about using a respirator....maybe its invisible, or my eyes are getting weak.

I think you are trying to start something. Its not neccessary. I have read this entire thread several times...

Why on earth would you be "upset" about this. its ridiculous. there are far greater things in life to bother a person. sheesh. Move on. Move on Brian.

DaddyQ (author)urbanwoodswalker2011-12-01

Step 3... Second paragraph
" I don't know what nasty chemicals are released when you vaporize foam but I would strongly recommend pouring outside and wearing a respirator with organic vapor cartridges in addition to your other safety gear."
Happy to help :D

Nobody wants to harm themselves unintentionally. It seems pretty obvious that you don't want to breathe smoke from foam or anything else. I do the casting outside and wear a respirator with organic vapor cartridges.

Not every one is sensible to do this, or even think of it. Just thought it worth mentioning. :-)

people die every year form grilling inside their garage........

People are known to do a lot of stupid things in life....I am doing one right now by replying...;-)

brianfss (author)2011-11-26

Nice job!
I'm going to scale down your design and cut it on my CNC router out of wax. The I'll use traditional lost wax and make the hearts out of silver. I'll have to add a small sprue between the pieces but that's the only difference.

spike3579 (author)brianfss2011-11-27

I can't wait to see pictures! Post some in the comments here when you get some.

What type of CNC do you have?

brianfss (author)spike35792011-11-29

I've got a CNC Shark Pro and a Roland MDX-40A. I'll use the Roland because it's a lot more precise and I'm just going to be cutting wax.

Tinkering_Pirate (author)2011-11-06

This is a very cool idea. Thanks for sharing!

.Unknown. (author)2011-10-04

Would it be possible to scale it down? Or would it just get messy?
I must admit, I was another person to think that they were rather small....

spike3579 (author).Unknown.2011-10-30

Try it and let me know how they turn out ;)

Calleja Mark 86 (author)2011-09-05

I'm thinking of a project, that consist of melting aluminium but i need to make a re-useble form/mould can any one tell me out of wich matirial could i do it please?

I would try steel or graphite. Make sure you heat whatever you use hot enough to drive out all the water but not so hot it sticks to the aluminum.

badideasrus (author)2010-10-06

holy --!!!!! i thought they were ring sized! how heavy are those suckers?

spike3579 (author)badideasrus2010-10-07

Everyone thinks they are small. I guess I need something to show scale in the photo. They're about 5" tall and weigh a little over a pound.

tomtortoise (author)spike35792010-12-04

yeah i thought they were like 1''

nrkey4ever (author)2010-07-25

that's such a clever design! I like it.

Kiteman (author)2010-02-24

First Instructable, first contest entry, and you're a winner!

Yay for entwined hearts!

spike3579 (author)Kiteman2010-02-24

 Yay indeed.  Thanks again
I'm afraid you've started something...    working on the next one now

Kiteman (author)spike35792010-02-25


TheFullMetalAlchemist (author)2010-02-22

 Thats well nice job you've done. I want to have a shot now, the possibilities!!

 Do it! Start today.  
You need to add casting metal to your extensive metal skills.  I've always wanted to be able to shape sheetmetal like you did on your bike.
I built my furnace over a few weekends for <$100  You can follow the build

Thanks for the info. It has gone on the long long projects to do list :), I bet you have one too.
 I hate you!! You've made me want to build that cnc mill of yours too hahaha!! Make that the next thing to add to the long long projects to do list.
You reckon it would work well with a plasma cutter torch instead of a drilling head? I think I'd cut more 2d shapes out of sheet, than milling objects. I figure I could cut thicker stuff (plate etc) without worrying about stressing the machine with the plasma, your thoughts??


 Absolutely you can use the cnc technology with a plasma cutter. In fact I think it's easier because you don't have to worry about rigidity.  The controller software that many people use ( ) even has settings to turn the torch on and off programmatically.  You can adapt the concepts from the wood router or look at plasma table builds on cnc zone.  There used to be an instructable on a diy plasma cutter that I wanted to build for a cutting table but it got taken down.  It seems like every project I complete just adds to my long long list of projects instead of reducing it.  Now I'm working on a 4th axis for the CNC and building foundry accessories.

Cylvre (author)2010-02-17

That's an excellent first casting!  Hope to see more 'ibles in the future.

One thing I would like to mention too is Dave Gingery's Complete Metal Shop series, it's 7 books that start you off with making an aluminium foundry and then detail how to make a drill press, metal lathe, milling machine, sheet metal brake, etc from standard metal stock and your own custom castings.  Great information and a lot of fun.  They're available from Lindsay Publication (no affiliation, just a happy customer):

Kryptonite (author)Cylvre2010-02-19

And I thought I was interested before. Metal lathe? Sheet metal brake? I'm there!

gamnoparts (author)Kryptonite2010-02-19

I've got that set, it's ridiculously awesome.  I miss ol' Dave Gingery. . . he was the epitome of ingenuity.

Kryptonite (author)gamnoparts2010-02-22

Sounds like it, are his books available via Amazon?

gamnoparts (author)Kryptonite2010-02-23

Yes. I got mine, though, from the Lindsay Books Catalog (Cylvre's link above).  Even if you get them from Amazon, I suggest you go to their website & request a catalog.  They have book reprints from the early 1900's about all kinds of industrial stuff.  It's a fun catalog to flip through if you have any interest in building stuff.  Also, if you're into steampunk. . . it's the original gangsta of steampunk. :D

Cylvre (author)gamnoparts2010-02-23

I'll definitely second requesting that catalog, Lindsay has books on just about every topic an instructibles junkie or MAKEer could ask for.  The level of technology from the old reprints means that it's usually pretty easy for the modern builder to replicate; early 1900 cutting edge industrial is the modern garage DIY'er... just on a HUGE scale.  Plus, it's funny.  The book descriptions, while getting all pertinant info across, are full of wisecracks and jokes about his neighbors and in-laws.  Gotta love it.

Kryptonite (author)Cylvre2010-02-24

*Mental note to get catalog now pending... DONE*

spike3579 (author)Kryptonite2010-02-24

 The Lindsay catalog and Dave Gingery'd books are both fantastic resources.  I also like Steve Chastain's foundry books and his site

frankboase (author)2010-02-21

Dear Sir,
Beautiful, but how to calculate the quantities required,and maybe rather a dumb question but where to get the materiel?

spike3579 (author)frankboase2010-02-22

 If you know the volume of the part you are casting you can multiply it by a weight conversion. ( 1cubic inch of aluminum = 44.2g according to WolframAlpha)  Some CAD programs will figure this out for you.  I just eyeballed it and melted way more than I needed.  You can always cast an ingot with the leftovers to use later.  You can melt anything that was made out of aluminum although remelting a casting works best.   Junkyards and mechanics are a good source for old engines or wheels.  

HEY YOU (author)2010-02-22

Nicely Done!

Please remember to use a dust mask when sanding aluminum as the dust is dangerous.


Morganbarker (author)2010-02-21

 gotta do something nice for the wife...after 2 years of building a cnc machine and foundry building, scrapping, BYMC'ing.  Lol, those look great by the way. -D.A.

frollard (author)2010-02-19

Excellent!  The toolpath really makes for quite a pattern on the final product!

RavingMadStudios (author)2010-02-19

Epic. Just epic.
The only suggestion I would make is to go ahead and de-sprue and finish the first shape before pouring the second, just to make the finishing a little less fiddly.  But wow, this is lovely.

You're right. It would have been easier to finish the first piece before casting the second but the furnace was hot...  If I was doing a production run I would approach it that way.  This was more of a proof of concept exploration.

Well, the concept is clearly more than sound. :-) Again, very well done.

Kiteman (author)2010-02-17


I knew this would be well-received, and a well-deserved Feature as well.


About This Instructable




Bio: I have a compulsion to make stuff, all kinds of stuff. I'm glad to be here...
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