That man is a genius
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Shop Microwave metal casting - some of the best videos I've seen
- Thread starter Mcgyver
- Start date
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Why? There are lots of dangers in handling molten metals of course, but as far as I can see, the increased risk with this is mainly around having molten metal inside a plastic cavity. It could lead a fire with noxious fumes. Not that that isn't serious, but its not a RF issue. It's also mitigated by the extremely high temps silicon carbide can handle and that the heated bit is inside a ceramic cocoon. There is also danger in the dust from various materials that shouldn't ignored but is easy to protect against.
I've been reading a bit on this, and apparently no metal in the microwave is a bit of myth. What you can't have is metal by itself
(no where for the energy to get absorbed so its starts arcing to the inside of the oven) or that is a shape that could arc (thin sections, pieces close together like tines on a fork). Even then danger is damaging the inside of the microwave from arcing, not rendering an unexpected new crater in your neighbourhood. The metal largely reflects the microwaves which doesn't matter if there is a bowl of soup (or silicon carbide crucible) present to absorb them and the silicone carbide is high absorptive of microwaves.
Definitely on the list ....... next job where cast iron is needed ..... and the wife isn't looking...... I'm going in boys
I do have to source silicon carbide which is quite expensive in small quantities, but I see some sand blasters carry it .....
Silicon carbide grit is available from any lapidary supplier. The grit size matters (not too coarse, not too fine) and I have acquired a 5lb bag of 150/220 grit which is perfect. It is known as Stage 2 grit if you're looking.
Harder to source in any quantity is the sodium silicate (water glass). I picked up a 4oz (100ml) bottle from Amazoom for $25 or so. However this stuff is hard to find unless you are associated with a school somewhere. Several Canadian suppliers have sodium silicate but they will only sell to an edu institution. Cost is about $20 per litre.
I have 3D printed the small flask mould from the video. The insulation should be here next week. Then I will need a peace offering for she who must be obeyed, in order to play with the microwave.
Proxule
Ultra Member
I made my own waterglass with kitty litter stuff ( silica gel ) and sodium hydroxide.
Easy peasy
Just found this, Its actually what I fallowed many moons ago,
How to Make Sodium Silicate - Water Glass
How to Make Sodium Silicate - Water Glass: Sodium silicate, also called waterglass is an interesting compound that is used in a variety of things. Water glass is a glue, a high heat cement or refractory, used to preserve eggs without refrigeration and as a sealer for concrete. My interest i…
TorontoBuilder
Ultra Member
He is only casting 3D printed items like benchies etc and I think that there is a serious limitation because his temps are too low to allow any serious pours. The metal cools too quickly.
Far better to go the whole hog decent sized foundry and waste oil burner with pressurized air supply. That is the route we are gearing up for with my brother and my friend.
The part that made me wince was using kitchen tongs on his crucible. I have enough trouble using those on a piece of meat, one slip on a hard crucible is probably going to lead to fried meat too…
I agree, was more thinking the whole microwave idea didn't seem particularly dangerous on learning a bit about it.
I am somewhat interested in this use of micro waves to melt also! I never could understand all the stuff about don't put metal in the microwave, my mother had one that was all stainless steel lined many years ago. The only thing that seems to have happened about 10 years after she started to use it was climate change "suddenly" began.
And that's a double LOL!
Anyway, carry on! Need to find a Kaowool supply, know where to get the tape, and round up some silicone carbide power. And let's see, project 10 move to spot 42, 42 to 101, Yada, Yada.
And that's a double LOL!
Anyway, carry on! Need to find a Kaowool supply, know where to get the tape, and round up some silicone carbide power. And let's see, project 10 move to spot 42, 42 to 101, Yada, Yada.
I don't have any particular expertise on the subject Mike. Call it instinct or the product of too many bad outcomes doing too many things nobody else does that went bad.
Here is what I said:
That didn't speak to any expertise. I even went so far as to say "MAYBE it's even ok".
I also said "maybe if a microwave engineer endorsed it, I'd change my mind."
Basically, it strikes me as one of those daring things people do and don't get hurt...... Until they do.
It certainly isn't as inherently safe as watching the sunset. Nor even cautiously dangerous like carefully handling a sharp knife, or lighting a bbq, or driving in heavy traffic, or calling your wife stupid. We all know those things have risks, but we do them anyway because experience tells us that the odds of getting hurt are low enough to be worth it.
For me, melting metal in a microwave is an unknown risk. Molten metal is inherently dangerous enough (as you acknowledged) without doing it using a process only ever done once by an unknown youtube actor under REALLY sketchy conditions.
I confess that your additional research makes me feel a bit better, but not sufficiently better to make it feel normal for me.
Frankly, I do all kinds of things I would never suggest that others do. This kind of fits that mold. It's something that might be ok for those that understand it or have the required expertise. But I don't fit that description and I don't think many of us hobby machinists do.
It's too big an unknown for me. For example, have you ever boiled a cup of water in the microwave that ended up superheating the water? Everything looks good until you bounce the cup on the counter. Then suddenly the water flash boils and sprays boiling water everywhere! Could that happen to metal? Who has researched that? What other unknown processes exist with microwaved metal? I get the heated crucible thing but how do we know there is no direct absorption? Why can't the metal act like an antenna? Maybe the wrong shape can!
You asked why I'm so cautious? As described above, the problem is that I don't know what could go wrong. I don't know enough to suggest possible risks. I don't even know enough to know what I don't know. And that's what stops me cold.
We're probably both unconsciously incompetent insofar as microwaving metals go .... was asking mostly because I wanted to know if you'd identified some cataclysmic flaw that hadn't occurred to me 
.
Here, hold my beer.......
Thinking further about some of your points, direct absorption would be good - more energy going into the metal directly. What would happen if it did act as an antenna? Not sure how that would matter, it's not connected to anything. The energy is either absorbed or reflected. The bad stuff happens when its reflected and there is nothing to absorb it .... then you get the arcing because it builds up.
.Here, hold my beer.......
Thinking further about some of your points, direct absorption would be good - more energy going into the metal directly. What would happen if it did act as an antenna? Not sure how that would matter, it's not connected to anything. The energy is either absorbed or reflected. The bad stuff happens when its reflected and there is nothing to absorb it .... then you get the arcing because it builds up.
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Proxule
Ultra Member
Where are you, I have some blanket kicking around. If it kicks your project up the list a bit. I am glad to help!
Tom O
Ultra Member
I got mine from Ceramics Canada a few years ago here’s the link.
Tom O
Ultra Member
This is on marketplace
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