Candles with a 3D printer & scanner

The CEO at my student job turned 70. Having a 3D printer & scanner at work there was only one thing to do: make candles.

pw-70-cake

pw70-cake3

Credit: shahrokh dini

Why not print the mold directly?

  1. I don’t have any ABS. I tried once and i didn’t like it. Wax melts at about 60°C and PLA gets soft at the same temperature.
  2. Even if you have ABS i recommend you to use a silicone mold. It will last longer and is soft and flexible. With this complex structure you need a flexible mold in order to remove the candle without damaging it.

pw-70-molds

What do you need

  • A 3d model. If you have a Kinect (or similar) and a good computer with the right GPU you can scan yourself (with the help of your friends/brother or your mom). Maybe a nearby hackerspace can help you. I did it with ReconstructMe and a PC-Kinect.
  • A 3d printer. If you don’t have one you can order a print online or go to your local hackerspace/fablab to print one (don’t forget to bring some beer).
  • Silicone mold mass. You can get it for 40€/kg on the internet or at some hardware stores.
  • Old candles or wax (+ color) and candle wick. I got 10cm long wicks with a little metal base plate: perfect.
  • Time.

PeterWeibel_V2_thingiverse

Safety.

  • Wax melts at about 60°C but that doesn’t mean that it can’t get hotter. Please be carefull.
  • The silicone mold mass is not healthy. Use gloves (and maybe glasses if you think it may splash).
  • Make it outside or in a place with good ventilation.

Prepare the model

  • Put your model on a solid base. Mine looks nice but is not high enough. You will pour the wax in the baseplate (the mold is upside down). A high baseplate makes the pouring simpler because it will not overspill so easy. 1cm is a good height and you are able to cut the wax afterwards to make a nice and flat bottom.
  • Polish and clean the model after it was printed. If you print your positive in ABS you can smooth it with Acetone (check out the tutorials on google and be carefull).

Make the mold

There are a lot of good and bad ways to make a molds. You can find them all over the internet. I will show you how i made it but i don’t say its the only or best way to do it.

With the 10cm wicks i scaled down the model to a hight of approx. 8cm. I toke an empty toilet paper core for the mold. Silicone doesn’t stick so this works really good.
You don’t want to wast too much of the silicone so get something adapted to your model size. Just keep in mind that you may be forced to destroy the container for easy removal so don’t do it in a metal can unless you are hulk.

  • Close on end of the tube with gaffer tape.
  • Place the figure on the bottom and press it against the gaffer tape so it doesn’t move. Check the distances between the model and the wall.
  • Think about how you will cut the mold in half later and mark lines on the paper roll or the bottom of the model.
  • Fill the mold with silicone and place it on a vibrating thing so the bubbles can escape. This could be a washing machine, an air conditioner or even your cellphone in nonstop-vibrating mode (this works but the vibration is a little bit too weak). I placed my mold on the small mobile air conditioner i have in my room.
  • After a certain time (written on the silicone packaging) it should start getting solid, at this point no need to shake it longer because the bubbles won’t move anymore. Place it somewhere and let it rest at least one night, 24h is better (this depends on your silicone, check the package).
  • Do something else and wait….
  • Remove the paper roll and draw the cutting line n the silicone.
  • Take a sharp and thin knife and cut the model in half.
  • Tadaaaaa….

Tools you need for the mold Preparation of the mold

Make the candles

Take some stuff you can throw away later or something where you don’t cook food inside. If you don’t have a mobile hotplate i strongly recommend to buy one because it is easier than cleaning your kitchen. Wear some old clothes. Even if you pay attention you will spill and splash wax around you.

You will need:

  • A pot for the wax and a stove. Be sure to have a pot with an opening on one side so you can pour the wax without spilling it everywhere like i did.
  • Rubbers or cable ties or something else to hold the two molds together.
  • Cold water (with ice cubes or similar).
  • Time.

Now…

  1. Clean and dry (!) the mold.
  2. Put the candle wick inside. I made a small gap in the top where it can be fixed.
  3. Close it with the rubber band or cable ties.
  4. Pour the wax slowly (!) in the mold.
  5. Tap against the mold so the bubbles can leave (!). You may need to add more wax. 
  6. Let it cool 5 to 10 minutes.
  7. Put it in ice water for at least 15 (!) minutes. This time is needed so the core of your mold can cool down. The silicone is not very heat conductive so this takes some time.
  8. Take it out, remove the cable ties and gently open the mold. I broke a few candles before a got the trick (the legs broke easily).
  9. Repeat from step 1.

Voilà!

No matter how careful your are the mold gets used and might break after several moldings. Especially the small details tend to break off soon. I made about 20 candles in each mold and i saw some cracks (because of the bending while removing the candle) appear.

pw-70-cake2 The molding processThe result