Introduction: Molding Bismuth for a Levitator
Bismuth is a brittle metal with a white, silver-pink hue, often with an iridescent oxide tarnish showing many colors from yellow to blue. The spiral, stair-stepped structure of bismuth crystals is the result of a higher growth rate around the outside edges than on the inside edges. No other metal is verified to be more naturally diamagnetic than bismuth. (Are repelled by magnetic fields.)
This makes them ideal for a non-supper magnet levitator.
I have wanted to build a levitator for some time, to build a levitator the two key ingredients you need are bismuth and strong magnets like neodymium rare earth magnets. Bismuth isn’t the easiest metal to machine it is heavy and brittle, if you try to bend bismuth, it breaks. However it melts at a relatively low temperature and molds quite easily. So I am going to mold the two disks of my levitator.
Step 1: Molding Supplies
Bismuth I got a one kilogram ingot.
Crucible; although most people use a stainless steel crucible, I used a Silica Crucible mainly because it retains heat and gives me time to mold the metal.
One safety precaution is you should wear cotton or wool clothing and slip on leather shoes. It takes a moment to be burned by molten metal, with cotton or wool the metal burns through the material and doesn’t stick to the skin. With synthetics the hot melted material sticks to the skin and burns. The same thing happens with the slip on leather shoes, the molten metal beads off the leather and if any gets in the shoe you can just kick off the shoe.
Step 2: Cold Shut
I have worked with steel, aluminum, cast iron, graphite, and ceramic molds. In all these metal molds you can get cold shuts no matter the metal you are molding, or what material the mold is made of. A Cold Shut is an unfilled section of the mold: some section of the mold cavity are not completely filled by the flowing metal, they can manifest as bubbles, cracks or lines, or unfilled sections in the metal.
The causes of this defect are; improper design of the mold, the mold is cold, or the molten metal is not hot enough to flow freely into the fine details of the mold.
Bismuth melting point 271.4⁰ C or 520.52⁰ F
Bismuth boiling point 1,564⁰ C or 2,847⁰ F
The best molding temperature is about mid-way from melting point and boiling point.
An old trick from bullet molding; was to dip the corner of the mold in the molten lead, and when the led didn’t solidify on the mold, the mold is hot enough.
Step 3: Measuring
Measuring out equal amounts of bismuth for the disks.
I placed the loose bits of bismuth in the silica crucible and melted the bismuth with a propane torch.
Once the bismuth was liquefied I heated up the square graphite mold and pored the bismuth into the mold until the mold was full.
When the mold cooled enough to solidify the bismuth I dumped out the small square ingot and repeat the process for the second ingot.
Step 4: Molding the Disks
Taking one ingot at a time I heated up the bismuth in the mold until it melted filling the bottom of the mold.
Once the bismuth cooled enough to solidify I repeated the process with the second ingot.
And there you have it Large ingot to small measured ingot to disk for the levitator.
Step 5: Making the Levitator Stand Parts
The stand looks more complicated than it is simple; it has 3 legs 3 plastic shelves and adjusting screw so plan it first to make things simple.
Step 6: Tools & Supplies
3. 6mm x 14 cm threaded rod
6. 11 mm locking nuts
12. 11 mm nuts
Plastic I salvaged from a computer LED flat screen.
Alinement bolt salvaged from an old tool.
Standard screwdriver modified to scratch deep lines in plastic.
6 mm Drill Bit
11 mm wrench
3 short 6 mm bolts
Step 7: Cutting the Plastic
I cut sheet plastic the same way I cut glass; etch one side, and bend at the etching until it breaks along the etch.
Using the square etch a 10 cm strip on one side.
Move the etch to the edge of the work table and press on the edge.
The sheet of plastic should snap along the etching.
Repeat for squares 10 cm a side, then corner to corner for triangles.
Step 8: Drilling the Holes
The drill bit should just fit inside the washer.
Clamp the three triangles together.
Drill a hole inside the point of the triangle.
Bolt the three parts together and drill the next hole in one of the points of the triangle.
Bolt the second hole and move on to the third point and do the same.
Step 9: Sanding the Edge
With the three triangles bolted together sand any defects off the edges of the plastic and round the points of the plastic triangles.
Then drill the last hole in the long side of the plastic triangles about half the distance in as the diameter of the bismuth slugs.
Step 10: Assembling the Levitator Stand
Remove the bolts holding the triangles together.
Making sure to keep track of the same side of the triangles separate them.
Thread a nut onto one of the threaded rods about 1 cm and add a washer.
Place the threaded rod into one of the point holes of the triangle and add another washer and the locking nut to the other side of the triangle. Tighten the nuts to the plastic making sure the threaded rod doesn’t pass through the locking nut.
Repeat this for the other two points.
Step 11: Second Shelf
Add 3 nuts and 3 washers to the threaded rod; thread the nuts onto the threaded rod until they are about 4 cm above the first shelf.
Add the second shelf and adjust it to the 3 nuts and washers.
Add 3 more washers and 3 nuts and tighten to the second shelf.
Add the two bismuth disks between the two shelves centered over the holes in the long side if the shelves and glue them in place.
Step 12: The Third Shelf
Add 3 nuts and 3 washers to the threaded rod; thread the nuts onto the threaded rod until they are about 1 cm from the end of the threaded rod.
Add the third shelf and add another washer and the locking nut to the other side of the triangle. Tighten the nuts to the plastic making sure the threaded rod doesn’t pass through the locking nut.
Remove one of the adjusting nuts from the alinement bolt and put it in the hole in the top shelf.
Replace the adjusting nut and add the magnets to the levitator.
Step 13: Adjusting the Levitator
Make sure the levitator is on a level and flat surface. If it is not level it will mess with you
Then adjust the magnets on the alinement bolt up and down until the square magnet between the bismuth disks float this may take some time until you get the hang of it.
Participated in the
Question 4 years ago on Introduction
If I molded a coin from Bismuth, would I be able to levitate it between my palms if I wore very strong magnetized rings on my fingers? Thinking of a magic trick ....
Answer 4 years ago
Sorry for taking so long to reply.
Sounds like a neat experiment the diamagnetic field of bismuth is not very strong so it might work if the magnetic field is strong enough.
Bismuth is very brittle, so you can't stamp lettering or images in it.
4 years ago
"This makes them ideal for a non-supper magnet levitator."
Reply 4 years ago
It is a shame you cant levitate a frog with it like a super magnet, that would be neat.
Tip 4 years ago on Step 1
Regarding the shoes - and socks. Molten metal is understandably dangerous, and the Rule is, if it can happen, it will. Wear boots that your jeans can cover the tops of. From personal experience during my youth, weld spatter bounced and landed inside my low-top leather shoes. I still have the scar. Cotton socks will char. Polyester, or any synthetic, will melt - into your skin, compounding an already bad situation.
Even for small pours, we pour a ring of sand around the mold beforehand. If the mold leaks, it's stopped before you become tethered to a wheelchair.
Reply 4 years ago
Molten metal is so hot the moisture in your skin instantly turns to vapor creating a barrier between your skin and the hot metal, just like a drop of water on a hot frying pan. Cotton and wool will burn but it will not stick to your skin like hot glue as Polyester will stick to you and burn your flesh until you remove it. Loose cotton, wool, and leather, enables you to throw off the burning clothing and stop the burns from getting worse. It is molten metal it will burn you the important thing is get it off of you quickly to make the burns less severe.
4 years ago
I found this whole process very interesting - thank you Josehf for a great Instructable! : )
Reply 4 years ago