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Author: Subject: Electric stove for metal casting?
Antiswat
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[*] posted on 19-10-2020 at 11:51
Electric stove for metal casting?


my lifelong struggle to easily melt aluminium has finally been settled. the key was to just get some high quality insulation and use what ive always had at hand- my electric kitchen stove
i was worried to crank it all the way up to heat mark 6 and keep it there, but it doesnt seem to cause any issues what so ever, on heat mark 5 i was getting just above 600*C reading (my heat gun overloads at 600*C)
using ceramic aluminium oxide wool i wrapped up a stainless steel cup in the wool, carefully covering the whole hotplate and after letting it stand around for an hour i was finally relieved to find the aluminium to have melted down

as for how much you can actually melt down on a stove im willing to say really depends on how great your insulation is, of what ive seen aluminium oxide wool is by far the best way to go, although i have also experimented with sodium silicate and sand cement, but this seems to require a lot of heating to properly cure and it can hold more heat than aluminium wool
https://gyazo.com/c1297361c81e085c9cdc41c649779e07

this takes kitchen chemistry to a new level and now low melting alloys are actually doable to mess around with without thinking about the weather outside, and i succeeded by simply wrapping the aluminium wool around the hotplate and the cup

i might be the first melting aluminium on a hotplate- the only results im finding online is people asking and people commenting that its impossible




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elementcollector1
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[*] posted on 19-10-2020 at 15:04


I did notice that aluminum foil melted when pressed against the heating coils of my stovetop, but I never thought to scale it up... Keep us posted!



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Herr Haber
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[*] posted on 19-10-2020 at 22:20


Is there a point besides proving it can be done on a kitchen stove ?
Dont misunderstand me, I like the idea of proving it can be done in a regular kitchen with just some insulation. One hour is not bad. How much material did you melt ?

You can find micro wave oven inserts that allow you to melt up to copper and silver. That's even higher melting and would allow you a broader range of experiments.
This means a few purchases such as crucibles but reduces the problems that may arise with whatever you are melting and steel.

I did have quite a laugh some months ago in my kitchen looking for a hot plate mitten. Who has 2 pairs of welding / high temperature insulated gloves in their kitchen ? :P




The spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words 'act upon' meant. - Ira Remsen
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Antiswat
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[*] posted on 20-10-2020 at 11:14


i melted down 120g of aluminium, but if the insulation is proper, then the amount wont really matter, when you can get some aluminium molten the rest comes very easily, only issue is if you scale it up you need to insulate larger area, it will contain more energy and radiate more heat
i scrapped a large heating element from an industrial air heater, removing the fan gets you a nice crucible heating element- now if i combine hotplate with that thing its gonna be some serious power

as for time to melt 120g aluminium, i really just forgot about my hotplate and i was slowly moving one heat setting up at a time, so it was already at like 600*C before i went to heat mark 6- could be just 10 minutes from cranking it up

i think rockwool isolation might work as well, went to autoparts shop today to get some muffler wool, but it doesnt appear to be nearly as dense or heat resistant as the chinese calcium silicate wool (doesnt seem to be aluminium oxide wool after all) but i think ill attempt to weld a top plate onto my heating element, stuff the walls of the heating element with rock wool and maybe some sodium silicate/sand mixture

also one really funny thing i noticed, my first run i tried to melt down recycled aluminium foil, i had squashed the foil in a metal tube with a hammer and a piece of cylindrical steel into a thick coin, about 10mm
i loaded a handful of these into my crucible and it just wouldnt melt
so i took one out and blasted with butane torch until glowing bright white- damn thing wouldnt melt, the aluminium oxide composite with aluminium kept it from coalescing, when pressed against hotplate i could see some of the aluminium was squeezing out, so if you want to make a very easy heating element for lab equipment, you could ram a large amount of aluminium foil and then carefully hammer "carve" the last bit to fit your flask, this should resist more than 1000*C by what ive seen

as for welding gloves, mainly welding flux core and some very thick steel i rarely use anything else but skintight gloves, the thin ones with rubberized fingertips, it will easily take 100*C off to the touch and as a bonus if you need to get some lab equipment apart they usually do the trick, superB for handling hot lab equipment, i doubt anything coming out of an regular oven could do much harm to those gloves

my newfound desire to melt metal at home is mostly that ive had 7 zinc bars stolen from my storage - thieves these days dont know what silver looks like, but its very neat to have the capacity to cast aluminium while dicing up some onions




~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
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zed
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[*] posted on 21-10-2020 at 04:23


Interesting that you did that. I recently used my stove top, to heat a 10 pound Cast Iron Weight disk.
To hold the heat in, I just inverted a cast iron frying pan over it. I was shooting to heat it red hot, to anneal it. It was too damned hard and tough, to drill and tap.

Well, on my stove, it blew out the stove element. Molten metal squirted out of it. Moreover, installing a new element didn't fix the stove, the controller also needed to be replaced.

Not terribly expensive as experiments go, but in the future I'll improvise a furnace that I don't need to use, to fry my flap-jacks.
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[*] posted on 21-10-2020 at 09:25


The metal tube mineral insulated elements are designed to work with a relatively cool pan compared to the melting point of aluminium or the anneal temperature of cast iron. Typically such elements are rated at about 600C. Go much above that temperature and the life expectancy drops dramatically.

I have tried to drill cast iron but its surface was very hard. I used a tungsten carbide spear point drill but it cracked before I got through. A plasma cutter works great on plate if you don't mind the irregular hole it produces. I have an 8in disc to cut out of an old piano frame. After I have cut it out I will try that annealing by putting it in a wood fire and letting it cool slowly in the hot ash. Hopefully I will be able to drill and tap it with HS tools.

Apparently on thin or small cast iron parts that cooled quickly after they were cast are very hard and brittle due to the carbon content in cast iron.




i am wg48 but not on my usual pc hence the temp handle.

Thank goodness for Fleming and the fungi.

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zed
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[*] posted on 22-10-2020 at 12:15


Well, my weight plates were very hard indeed. At least, parts of them. I was crafting ring stands. I was able to drill and tap holes, in some plates, but not consistantly.

I must imagine the plates were quenched, while still quite hot. The cast iron being in some places, converted to carbon steel. High speed steel, would not drill it properly, even with constant re-sharpening.

If the cast iron was produced from scrap metal, who knows what the alloy might actually be?

It's much tougher than expected.
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[*] posted on 23-10-2020 at 02:00


Cast iron is more carbon steel than carbon steel is. It will quench harden even with extremely slow cooling rates. An annealing on the timescale of days is required to soften it.

OP: You don't need fancy insulation for aluminum. I do a lot of diy metal casting. Just use ordinary wall insulation, the rockwool or glass fiber kind. It will keep most of its important properties up to 800°C or so. It does lose some structural properties in the 300°C range due to some polymerish binders being destroyed, but that just makes it a bit fragile and doesnt affect it as long as you don't try to rearrange it. The first heating will stink a little because of this(and most probably isn't healthy) so that's best suited to do outside, but it also only needs to be done once.

That said, I gave up on electric heating a long time ago. You just can't get enough power to do anything meaningful in an acceptable amount of time. I use a dead simple air/liquid sprayer and use diesel for my heating needs. I've estimated it to be about 100 kW. I'll melt a kg or two in less than 3 minutes even without any insulation. :)

[Edited on 23-10-2020 by Junk_Enginerd]
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[*] posted on 23-10-2020 at 07:24


Junk_Enginerd (previous post) had me worried that to anneal cast iron would require a soak of days.

See https://www.model-engineer.co.uk/forums/postings.asp?th=9097...




i am wg48 but not on my usual pc hence the temp handle.

Thank goodness for Fleming and the fungi.

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[*] posted on 23-10-2020 at 09:34


I want to be able to melt some aluminium, copper and maybe gold.
I have decided to make a DIY electric furnace as its quite cheap and relatively easy.
Im going to drive it with FeCrAl heating coils and i have bought a box of high temp bricks to make the furnace.
Its not a prioritized project but is nice to work such things during winter evenings.
I saw someone on Youtube that built an oven with high temp bricks and a stove element.
It didnt say anything about how long the heating element did work before failing though.
Regarding insulation there is these ceramic "blankets" one can find on ebay that is used to insulate ovens, furnaces and things like that.
They can be found in some different thickness.
I would guess those are pretty good for insulating where temps go high.
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[*] posted on 24-10-2020 at 05:28


"Molten metal squirted out of it."
thats strange, not sure what kind of stove youre running but afaik the heating elements wouldnt naturally be nichrome or something even better, which naturally doesnt melt at below 1500*C, and steel doesnt either (well it gets soft with heat) - what kind of metal was it, any clue? the heating elements are typically made with nichrome wire in steel tube sorrounded with aluminium oxide so they stay in place

zed, if you have access to a welding apparatus you could test if its hardox, its a lot harder than carbon steel despite being around 4% alloying elements, you can weld some carbon steel to it, if the weld later on cracks i'd call it likely hardox, not an expert of welding the wrong alloys but thats how it works when you put carbon steel to hardox

also, for annealing you wanna place the heated material in sand, this greatly insulates and keeps the steel hot for longer, better results
also, i believe its up to 600*C you will get annealing benifits, while some hardening can be lost already at 200*C

to check if its higher carbon steel, hold an angle grinder to it, the more sparks the higher the carbon content- generally

yes mateo_swe, theyre great but if you wanna make the whole deal solid you wanna go ahead and get some sodium silicate, mix that with sand so it gets damp, use this as cement, this is basically what furnace cement is made of, it holds up very well to heat and doesnt let much through, and you will never get it off something you let it dry up on, turns into glass

i did play around with calcium silicate but with copious experimentation it seemed that ... was it 60% sand 40% sodium silicate solution was what worked best and easiest, using other compositions just gave me brittle results

one very interesting thing ive seen was first shown by youtuber "AvE" where he heats up toast bread in a sealed metal container with argon, the pyrolyzed product is some type of carbon thats super insulating, though very brittle, if we could find a way to crush this up and use as some type of granulate, maybe carefully stir that up with sodium silicate or soak up some sodium silicate solution with an excess of this carbon like powder? it has great potential.





~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
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elementcollector1
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[*] posted on 24-10-2020 at 06:27


Quote: Originally posted by Antiswat  

one very interesting thing ive seen was first shown by youtuber "AvE" where he heats up toast bread in a sealed metal container with argon, the pyrolyzed product is some type of carbon thats super insulating, though very brittle, if we could find a way to crush this up and use as some type of granulate, maybe carefully stir that up with sodium silicate or soak up some sodium silicate solution with an excess of this carbon like powder? it has great potential.



It does, but only really works in a vacuum - much like a graphite crucible, exposure to air burns carbon foam away over time.




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[*] posted on 24-10-2020 at 12:21


Quote: Originally posted by Junk_Enginerd  
Cast iron is more carbon steel than carbon steel is. It will quench harden even with extremely slow cooling rates. An annealing on the timescale of days is required to soften it.

OP: You don't need fancy insulation for aluminum. I do a lot of diy metal casting. Just use ordinary wall insulation, the rockwool or glass fiber kind. It will keep most of its important properties up to 800°C or so. It does lose some structural properties in the 300°C range due to some polymerish binders being destroyed, but that just makes it a bit fragile and doesnt affect it as long as you don't try to rearrange it. The first heating will stink a little because of this(and most probably isn't healthy) so that's best suited to do outside, but it also only needs to be done once.

That said, I gave up on electric heating a long time ago. You just can't get enough power to do anything meaningful in an acceptable amount of time. I use a dead simple air/liquid sprayer and use diesel for my heating needs. I've estimated it to be about 100 kW. I'll melt a kg or two in less than 3 minutes even without any insulation. :)

[Edited on 23-10-2020 by Junk_Enginerd]

Never heard about Kanthal furnaces ? They work very well, can be DIY and Kanthal wire can easily be ordered online on ebay or Amazon. I have two such (small) furnaces made myself. For melting aluminum it is really easy and it even melts copper as the furnace can easily reach 1200 C.
An electric stove is totally unsuitable for metal melting unless you don't go beyond 420 C (zinc).
But in the upcoming years induction furnaces will become more affordable for amateurs.
For melting metals I now mostly use gas (propane or natural gas).
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Antiswat
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[*] posted on 25-10-2020 at 06:05


what i dont like about making your own furnace is that youre gonna be dealing with having to find something to fit the wires inside of- and the typical response that echoes is "just buy firebricks" (and then spend long time chiseling that out properly and correctly
anyhow- i just poured my first MgAl bar melted from my kitchen stovetop, if you have a backyard or whatever sure, using propane is very doable, theres people on youtube who made diesel burners for this purpose.

so far for this setup ive used rockwool, some glass like fibers used for insulating car exhaust silencer and calcium silicate wool, the calcium silicate wool is no doubt the highest quality stuff you can get for the job and rings in at about 20 dollars for 24x24" piece
if youre using a hotplate you want to either have patience or maximize the insulation youre using, now im wondering.. if i made an outer shield for my construction, wouldnt that reflect the heat, if its polished stainless or aluminium? like a thermal blanket, there are also some suits used for high temperature like steel casters that are some kind of reflective material

if i wanted to go all fancy on metal casting i could just get me some butane and oxygen, you can get some pretty big heater heads for those things, we got some heads that are about 50mm in diameter at my job, lighting that thing up with proper oxygen balance and no hearing protection on will leave you deaf for a bit

another thing i really like about these already made heating elements is that you dont have to worry about shorting out because its all nicely compacted into aluminium oxide inside the steel tubes, so it will stay in place- however my build is to have a round heating element with a tube that came with the heater around it, then insulation between the sorrounding steel plate, and ceramic wool on top/bottom- but it seems that the heating element gave up after being heated up throughly, which is very sad, when i first turned it on the heating element got redhot within 5 minutes or so, and because the coil would sorround by crucible it would translate into very high efficiency compared to just heated from the bottom and up

my first run was melting down about 175g Al and 175g Mg, i first melted the aluminium (took maybe 3 hours or so to heat up properly, 5mm thick steel crucible) and then dunked in the Mg rods, 30 minutes later it was ready to pour, the resulting bar came out with 9 grammes deviation to my calculations (250g per bar mold)
so, i chucked in 300g more aluminium and 23 minutes later its still not molten, seems aluminium has higher heat capacity.

image of the kitchen metal casting setup, metal plate and pieces of steel ontop to weigh it down a bit, the top reaches about 45*C where the sides are at 110*C- seems i need to pull out that heating element and replace with insulation instead
https://gyazo.com/6a1c3e24eeb3cd37fa4ceb4d1c6be3c5

image of the casted metal bar
https://gyazo.com/290eb1fcb13bb0b7445b1a8ce4f283d3

i added a metal plate to my stovetop just incase i would cause a spill or some other exciting event would play out, plus aluminium foil that i crimped up around the bar mold just incase of a spill, so the metal would by no means get to run away for me
as for how the stovetop is feeling, im using the one burner that i never use, and i have previously been running it for an amount of hours when messing around with nitrate to nitrite decomposition at almost full settings, looking into how those things are put together if it does pop its likely from the plastic parts underneath melting apart or what not, but they seem doable to replace, not that you couldnt just use a single electrical stovetop burner instead


now that im thinking about firebricks, i think you could make your own and "chisel" out the spacing for the wires by simply putting in some steel rods running at 30 degree angle, but you wanna make all 4 walls at the same time, then you simply chop the whole plate with the slits in it apart into 4 equal sections and chuck it in oven at max temperature to heal up well, then you can just shave some of the top or bottom off to get the grooves to fit next to each other for smooth transition, as with heating coils you need a spiral that it can run around in from top to bottom




~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
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Herr Haber
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[*] posted on 25-10-2020 at 08:43


Were you ever tempted by induction ?

There are decent modules out there that would cost you about as much as the insulation and bricks you are using.
I've got one that I still have to assemble.
I'm pretty sure it's a lot more energy efficient than a normal kiln with a resistance.




The spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words 'act upon' meant. - Ira Remsen
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[*] posted on 25-10-2020 at 13:04


i think i did read up on it briefly and also came across people asking if you can use induction hotplate to melt aluminium, of what i saw people were saying its not possible because it works on magnetic objects which aluminium is not and i know that glassplates can crack if theyre heated too much- but glassplates arent really a must. i mean i can def get hotplates, by the tonne, some digging and i should find induction glass plate
ok so, it works on electromagnetism, but that would imply loads of electromagnetic radiation right? i would wanna massively shield that thing. is there any way to absorb EMF waves, because aluminium would just redirect those waves

ill try to see if i can scrap an induction hotplate, but once you rip that thing apart its probably gonna be problematic with getting the right volt/amps delivered to the device itself, but it seems very compact and like it has great potential




~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
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