How to Make Your Own Crucibles (for microwave metal melting)
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- Опубликовано: 9 фев 2025
- In this video, I demonstrate my current method for making crucibles at home for microwave metal melting. They are made using silicon carbide and sodium silicate, then hardened with ceramic fibre.
New Molds from Patreon / shakethefuture
New Molds from Printables www.printables...
Old molds www.printables...
Affiliate links:
Silicon Carbide amzn.to/4aR2EkE
Sodium silicate amzn.to/3EvoaiU
Ceramic fibre amzn.to/42PQ9Ec
Kiln Paper amzn.to/4hvAwWN
He's not kidding about using the respirator. At these temperatures, the fibers aren't even the worst of your worries. Many compounds break down into highly reactive chemical compound that can and will destroy your lungs. Plaster for example will break down into calcium oxide and hydrate inside your lungs to highly caustic calcium hydroxide and to make matters worse the reaction is highly exothermic so you get heat burns on top of the chemical burns IN YOUR LUNGS. Many compounds besides plaster behave similarly at high temperatures and since you'll be using a microwave kiln with no real temperature control, you won't know exactly what toxic or caustic compounds may have formed in localized temperature extremes... so use the best breathing protection you have along with as much ventilation as possible... or have really good health and life insurance.
This is so absolutely right. It's not in the realm of "it'll be okay just this once." You can mess yourself up a LOT with one exposure.
Most of the time, I use FEPA 220-grit silicon carbide, but lately, I've been experimenting with coarser and mixed grits. I’m not sure how they perform yet, as testing takes time. In theory, a mixed-grit silicon carbide (fine + coarse) could be beneficial, but only time will tell.
These molds are a significant improvement over the previous versions. I'll continue updating them and adding more sizes. The next addition will be a tiny crucible. I haven’t published it yet because I needed to resolve an issue, and I didn’t want to delay this video.
I’m trying to publish videos more frequently! :)
Finer grits and better finishing (less porosity) make it more efficient and support higher temperatures, but will be more difficult reach the right density to make the crucible.
@@ShakeTheFuture A good balance is to use coarser grit at ~75-80% and finer grit for the remainder. This is based on the mathematics of sphere packing and experimentation in the concrete industry.
Vibration is necessary to get the optimal packing though.
Basically imagine a matrix of stacked bowling balls, you would want the next set of filler balls to just fit between without displacing the bowling balls - perhaps golf ball to racquetball size, then the next size to fit in those remaining spaces perhaps BBs to marble sized, and so on.
You can do this down to the finest grain size you have available and the remaining volume is the minimum liquid binder you need. If you try to get too close to the minimum binder though it requires much more physical work to get the best results - failure to do so may leave weaker areas than if you'd have just added excess binder.
A basic concrete mix is one part cement, 2 sand, 3 gravel. Also, crushed stone with irregular shapes tends to be stronger than rounded gravel and sand. Having more cement and fines than optimal packing would seem likely to work better than less.
Another possible experiment is SiC mixed with other material. I read an article awhile back describing melting metal in crucibles using both silicon carbide and magnetite, one being more efficient at absorbing microwaves at low temperatue.
@@sevazinhogamer9521 Thanks!
@@RandyCampbell-fk3pf Thanks for the info!
I practiced crucible making for years years before I ever needed one. But I'm so glad I had that experience when the time came. So to speak.
Yep, you never know when skills practiced will come in handy
Denny, thank you for another great video...I've been watching you for several years....I think the first time I found your channel you just made the secret tie that holds a drink....keep up the good work...I love all you do...watching you from Dallas Texas....Cheers my friend!
Thank You very much! Oh yes, that video. It seems like a lifetime ago :)
*Crafting Durable Crucibles: An Updated Guide to Silicon Carbide and Sodium Silicate*
* *0:00** Introduction:* An updated version of the crucible-making segment from a previous microwave metal melting video is shown.
* *0:12** Materials Needed:* Silicon carbide (fine, medium, or a mix of coarse and fine grit) and sodium silicate (water glass) are required. The suggested ratio is 8-10% sodium silicate by weight.
* *0:37** Mixing and Filling:* The silicon carbide and sodium silicate mixture is added step-by-step into a mold (glass or 3D printed) and pressed down firmly.
* *0:50** Shaping the Crucible:* Tools such as wooden sticks or 3D-printed tools can be used for pressing and shaping the crucible.
* *1:14** Microwave Curing:* The crucible is placed on a ceramic fiber sheet and microwaved until the glass cracks (ice cube can be used to accelerate cracking but be careful to not overdo it).
* *1:48** Finishing:* Sanding tools (files, sandpaper) are used to refine the shape of the crucible after removing it from the cracked glass.
* *2:05** Pre-Heating:* The crucible should be heated in a metal melting chamber before its first use.
* *2:24** Hardening (Optional):* Hardening makes the crucible stronger and less prone to cracking. Whether it's needed depends on the crucible's shape, thickness, height, and intended use. Hardening naturally happens when used with high melting point metals or fluxes.
* *3:20** 3D Printed Molds:* 3D-printed molds (available on printables for old molds, Patreon for new) can be used. New molds offer different sizes and thicknesses.
* *4:10** Mold Assembly:* A lid (printed in soft filament is recommended), M5 screw with a hook, and binder clips are used to assemble the 3D-printed mold.
* *5:06** Pressing Tools:* Custom press tools with a handle increase pressing efficiency. Tool for adding air also exists.
* *6:56** Freezing:* After filling the 3D printed molds, freeze for at least 2 hours to help unmold the crucible
* *7:40** Hardening Process:* The crucible can be hardened by wrapping it in ceramic fiber, securing it with rubber bands, and microwaving until it glows red. Once cooled, the ceramic fiber is scraped off (wear a respirator).
* *8:55** Downsides of Ceramic Fiber:* Working with ceramic fiber is messy and requires protective gear (respirator, gloves).
* *9:55** Alternative Hardening Method:* Using ceramic fiber kiln paper (for glass fusing) glued to the crucible with school glue is a preferred method.
* *10:30** Ceramic Fiber Kiln Paper Method* the user is still advised to wear gloves.
* *11:01** Heating with Kiln Paper:* The crucible with kiln paper must be heated well until the paper disappears or fuses with the silicon carbide.
* *11:43** Benefits of Kiln Paper:* This method is better, cheaper, and avoids the downsides of loose ceramic fiber, but works best with smaller crucibles.
I used gemini-2.0-flash-exp on rocketrecap dot com to summarize the transcript.
Cost (if I didn't use the free tier): $0.50
Input tokens: 19450
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To avoid the negatives of the ceramic fiber, it could be used in a glove box, like the type sometimes used for sandblasting parts.
Oh yes, that's a good one to have… if you have the space! 😀 If I ever move to a different location one day and get a proper workshop, that’s one of the things I’ll get.
Gracias por compartir hermano, Saludos desde Colombia.
Also you could re use all the shattered glass and pulverize it and mortar it into a powder and add lye to it or woodash to make more sodium silicate.
"Crystal" cat litter (basically silica gel) and drain cleaner (sodium hydroxide) are the easiest ways to make it from scratch, but most big box hardware stores carry it near their concrete section.
The pulverization of glass should work theoretically but I tried it with both sand and crushed glass and no matter how small I got the particulate, the reaction was just too slow. There was a process to speed it up, but I didn't want to use the extra chemicals and perform the extra steps to remove the byproducts.
That's awesome!
9:54 You can seal the ceramic fiber with alumina slurry and harden it to keep the fibers in place
Have you played around with making your own glass? It'd be really cool if you could try to make a lens. Maybe something simple like for a magnifying glass as a test.
Cool method! Have you tried making openable permanent or semi permanent molds this way? Like for actual gravity casting of metal.
Maybe needs skimming off with a cnc mill.
I have not tried it yet, but it's in my project list. Cheers!
Brill video thank you. I wonder if you could put a layer of tissue paper between the new crucible and the fibres. Maybe the carbon residue would help prevent the fibres sticking to it so much. In diesel forges we use some cardboard between the plinth and the crucible to stop it sticking.
Oh you are literally doing that!!!
Thanks for this guide!
Which 'grit' of silicon carbide do you use?
Could you go over the ceramic fiber insulators/refractory, the generic types, the alternative materials, procurement, material specifications etc... ?
I’d love to experiment with different materials. There’s an 'organic' version of ceramic fiber-I don’t remember what it’s called-that I’d like to try. It’s supposed to be less nasty, but unfortunately, all these things cost 💰, so right now, it’s not that easy to dive into any project I want. Hopefully, we’ll get there soon. Cheers!
@@ShakeTheFuture What about using different material layers. Especially an air tight outer casing. Would insulating the microwave help reduce heat loss enough to be worth it ? What about castable refractory insulator like vermiculite cement plus some suitable insulating aggregate ? What about rock wool or fiberglass insulation for the outer layers ?
Great video as usual... But was the end intended to be so abrupt? 😉
Thanks! I wasn’t at my usual location-I was staying at my mother-in-law’s house. I brought my computer to edit and finish the video while also doing a three-day water fast, so I wasn’t feeling 100%.
I really wanted to get the video out this week since I’m trying to publish weekly, so that’s probably why it ended up the way it did. It was one of those moments… 'Good enough for me, let’s move on!' 🙂
If i will have lathe, i will try make sort of cup size form to press SiC with BENTONITE in it with hydraulic portable car lift.
It probably can make many time use melting pot, because liquid glass work
Legend!!
Cheers!
Thank you for this and all your other microwave videos. Questions:
What temperature do you need to harden the crucible and can it be done and in an electric kiln or a propane furnace?
Thanks! Well, that’s a good question to which I don’t have an exact answer, since I’ve only used a microwave to melt metals and have no way to measure the temperature that hight.
However, judging by the brightness of the crucible, I’d estimate it’s somewhere between 1,050-1,250°C. That said, I don’t know what would happen if you heated the crucible to a lower temperature and simply maintained it. Maybe holding the temperature for an hour would produce the same result-I’m don't know.
With my setup, I can’t really maintain the temperature for too long, as the chamber gets too hot. Heating that crucible took me around 20-25 minutes of microwaving. Cheers!
@@ShakeTheFuture The melting point of Silicone Carbide is up around 3,000°C I wonder if the Sodium Silicate acts as a flux to lower the melting point so it can fuse together. White hot is about 1,200°C on up. Amazing how precise and efficient the microwave is in heating only the crucible. The propane furnace is ridiculously inefficient. I would not be surprised if you got the SC up to 3,000°C.
It is 2AM and recalling temperatures from memory so I probably got them wrong.
Where do you even buy silicon carbide powder?
It's sold as sandblasting media, an industrial supply, in 10Lb and 50Lb bags. Hit up a painting supplier, or a large hardware store. (not the chains, the ones contractors actually use)
They will also sell the relevant PPE (respirators, gloves, etc.), and it's well-worth investing in a good respirator.
@@jercos Yep. I buy them from sandblasting stores.
Nice video! Can you measure the conductivity/resistance of the silicon carbide crucible to see if it can be used as a heating element to be used in high temperatures?
Using this method you can melt anything that exists, it holds really good until near 2500°C, above this you only able to melt a low amount and for like 2-3 times before melting the crucible too
@@sevazinhogamer9521 Sorry, I meant electrical resistance. I was thinking about making silicon carbide resistors for a high-temperature kiln this way and was wondering if the silicon carbide particles in your crucible were electrically connected when mixed with the sodium silicate and then hardened.
@lmkawakami I've worked with sodium silicate a lot, it's not electrically conductive. Can't comment on silicon carbide but I doubt it would be either in practice.
I tried to measure it, but for some reason, my multimeter is showing 29.2Ω even when I’m not touching anything. When I touch the leads together, it goes to 0Ω. However, when I touch the crucible at two points, the reading doesn’t change and just stays at 29Ω
This got me thinking if I might save on crucibles by making them, and thinking about using Rock Wool and firebrick as insulation. Ceramic fiber, kind of worries me.
8:08 Rätselhaft, warum der Tiegel glüht.
Bei Wikipedia ist ein interessanter Beitrag zum Aushärten zu finden: "In der Gießereitechnik kann Wasserglas als Bindemittel für Sandformen verwendet werden. Dabei wird das Aushärten meist durch künstliche Begasung mit Kohlendioxid beschleunigt."
have you ever tried using the microwave for heat treating/tempering?
I have not, but i don't see why it would not work. Cheers!
Do the patterned crucibles do anything extra, or is it just aesthetics?
The pretty ones are for aesthetics but you can use the patterns to allow for more secure grip with your tongs.
For example, if you were going to use your dad's gooseneck pliers to pour, you could leave the center support in and grip into the side a couple of times before firing.
Maybe at the top lip too for pulling it out.
It’s more for the look. I realized that all crucibles look the same, but they don’t have to. I know, I know, it’s not that important, but I bet if people had the choice between a regular crucible and one with a nice pattern, they’d probably go with the patterned one-because why not?
That said, there’s another reason, but don’t believe everything I say. I have a theory that some patterns might increase the strength of the crucible. Obviously, it’s just a theory that needs to be tested. I’m going to start switching to patterned crucibles and see what happens.
Then again, I’m also experimenting with mixed grits and these new 3D-printed molds let's you pack silicon carbide better, so there are a lot of changes happening at once! :)
Maybe I should have introduced only one change at a time to figure out exactly what makes a difference. Apart from the patterns, I’ll also add crucibles with text on them-like brass, aluminum, silver, etc. That way, it’ll be easier to identify which crucible is meant for each metal if you only want to use one crucible per type. Cheers!
Future video: "How to Make Your Own Giant Microwave Oven".
What is the stainless steel contraption in the back I saw at 1:24.
That's a cereal grinder that I use to grind silicon carbide.
@@ShakeTheFuture Which one wins? Since silicon carbide is an abrasive.
you ever tried making alumina or silica crucibles?
No, because I need them to heat up in the microwave. If I were to use them with gas furnace, then I would explore alternative ways to make crucibles. Cheers!
what is the max weight of say bronze that you can melt in a microwave ?
It depends on many factors. So far, the biggest crucible I’ve ever used was the one in the chair melting video:
ruclips.net/video/xyzE413rqHU/видео.html
It’s almost the same size as the 3D-printed 'Large_tall' molds. In that video, I melted aluminum. I haven’t tried filling a crucible that big with bronze since I don’t have a lot of it. Brass could definitely be melted, but it would take longer.
If I remember correctly, I melted around 450g of aluminum in that crucible. As for bronze, one piece I made weighs 320g. That’s not the maximum capacity-I just didn’t have more metal at the time. I’ve also melted around 300g of iron.
It also depends on your setup. For example, the setup I used in the stainless steel melting video, where the crucible is embedded/covered with ceramic fiber, can reach higher temperatures and melt metals faster. However, there are downsides to that method. I hope to make a video about it as well.
Cheers!
Thanks for the great videos!
I also made a crucible and insulated container based on your video.
It worked well up to the point of firing the crucible. I was able to make a hard crucible that made a high pitched sound when tapped.
However, when I tried to actually use this crucible, a problem occurred. When we grabbed the red-hot crucible with tongs, it deformed like cookie dough.
Did we put too much sodium silicate in the crucible? Or was the sintering temperature too low? (I heated it up to about 1100℃)
If you have any advice please.
Thanks again for the great video!
I used to have that problem as well, but not anymore. I would suggest trying to decrease the amount of sodium silicate used, or the opposite, increasing it. Obviously, it can also depend on the brand or strength of the sodium silicate. The one I used is a 37% solution. I know that on amazon there are gasket sealers that's pretty much the same sodium silicate, but they are only 10% or something like that.
So yeah, I’ve been there before. If you're packing the silicon carbide well enough and your crucibles are still falling apart, try using finer grit or experiment with the amount of sodium silicate you add. Cheers!
@@ShakeTheFuture
Thanks for the reply!
I will try different concentrations of sodium silicate!
I'm just going to throw out some advice for dealing with the fibers that get on your skin. Only use cold water to wash. Yes, take a cold shower and all. You really don't want you pores to open up with warm or hot water.
where you come from? you're accent says "i'm not english/american" ;)
You may already know, but you can cure waterglass with CO2. It's near instantanious.
Yes, I’m aware of that, and I used to use CO2, but it became an unnecessary expense, so I stopped refilling my CO2 fire extinguisher and switched to alternative methods. Cheers!
Liquid glass Im hardening by co2 gas at room temperature in 24 hours. I use co2 from old expired fire estinguisher
I also used to use a fire extinguisher, but I stopped because I was using way too much CO2. Not necessarily because I needed to inject a lot of CO2, but more because it was a psychological thing. 'Let’s inject a bit more... just in case.' I found myself refilling the CO2 way too often, so I stopped using it.
3 ads in 12 minites video, pay to get the design, on a channel with almost 200k subs, 196 patreons and god knows how much youtube memberships... when is it enogh? you are killing the growth of your channel...
I don't think creators control the number of ads that plays in their videos. That's youtube.
you are living in a cave and never heard of adblockers?
Thanks for the comment. That’s interesting, but it looks very different from my side. I don’t usually like to talk about these things, but let’s go there-why not.
I earn pennies from RUclips. You know those videos where people share how much they’ve earned from RUclips ads? I watch them and sometimes think we’re in different universes.
My average earnings from RUclips ads are 300-400 euros a month, which is approximately the same in USD. I’m also self-employed here in Spain as a digital content creator.
I have to pay the government 230 euros a month just to stay self-employed. In other words, there have been too many times when my RUclips earnings barely covered that cost.
I have 196 patrons, including free ones. Only 47 of them are paid, which adds up to 146 euros a month.
In other words, there’s no money. There’s a reason I don’t make more videos on certain topics-it all comes down to money.
As for selling the model, what I wrote above explains it all.
At the end of the day, I’ve spent 5 years of my life experimenting with these microwave metal-melting methods, and I’ve shared a lot of info for free.
In the original edit of the video, I said something like: 'You can get these molds from Patreon or Printables, because at the end of the day, I also need to pay the bills.'
I deleted that part of the video because I didn’t feel the need to justify why I’m charging for the molds. I also need to provide value for my patrons, and it’s not fair if I offer everything for free. They should get something out of it.
If people want, I can make one of those RUclips 'How Much I Earn Per Month' videos to show that not everybody is a RUclips millionaire.
Cheers!
@@SrObser they do
@@Zyczu55 there are no adblockers for youtube mobile apps...