Vevor Furnace: s.vevor.com/bfQYTT BE CAREFUL WITH THE CRUCIBLES Want to learn sand casting using your 3D printer? I can teach you!: paulsmakeracademy.mykajabi.com/joinus
4 месяца назад
Got a tip for you. I been to a place that makes copper tubing and the melt massive amounts of copper very crudely then their is a channel in the floor and the copper flows into giant ingot molds. Either way, when melting they throw a whole log on the copper (oak or pine, I can't remember) and when letting it flow they stick charcoal brickets on top of the copper. They both reduce the atmosphere and somehow lower impurities. It must work because extruding and pulling copper has to be pure or you can imagine the issues that would arise.
I had a 3 kg graphite crucible break when I added some aluminum to it. The bottome broke out. I weighed it. It weighed 188 g and a new one was around 350 g. I got it pretty thin with silver and aluminum. Now I weigh my crucible and if it is below 200 g I stop using it. So far so good.
Have you tried casting molten water? I've had problems with it because the density decreases almost all the way to the freezing temp, so it increases in volume and that has to be considered when choosing a casting medium... I've had good success with a flexible silicone mold. It does require a special freezing unit, as water is molten at room temperature. This does help with the re-casting of mistakes. Also, depending on the size of your freezing unit, the casting can be used in displays, or even be stored for later decorations in other liquids or mixtures of liquids, even as auxiliary cooling units for those liquids. I've even heard of people using these casting for medical purposes... go figure. Happy Saturday.
I was thinking of doing some chocolate or maybe casting various foods (bread, tuna or maybe hamburger?) but I'm not sure that may require a specialized heating unit and you might want to reserve it just for the purpose of foods, as it is probably not good to mix food preparations with other castings. Time will tell... but it's can be very exciting from what I've researched.
actually making your own chocolate in molds should be easy enough. My neighbors run a chocolate company out of their home, it's most food safe silicone casting and then heating in a cooking pan on the stove top. I'm sure their house smells fantastic but i might not fit into my pants anymore if i spent too much time over there 🤣
I'm "that guy" Paul mentions. Lost 2 x Furnaces (so far) with crucible failures (over the years to be fair). I could be moisture (but I store mine on the casting table), I don't think it is metal expansion (as I keep one full of pewter all the time that I melt, let freeze in the crucible, remelt over and over without issue), but I DO think it is due to them being inherently brittle and more susceptible to crack at high temps like 1000c. My best guess is I put a hairline crack from dropping ingots into it (don't do that!), and the second from chipping the edge of the crucible on the thermocouple (what was at a weird angle on that furnace). Anyway. I now load my crucibles GENTLY and try not to knock them over (which is hard given the are tall and skinny).
Yep, concrete floors, even with a membrane underneath them, are a potential water wick. Never store bags of cement straight on a concrete floor, they’ll suck up moisture eventually and start going off.
When I start using a new crucible I will melt copper or bronze no more than 7-8 times until I demote the crucible to Brass, do that about 5-8 times depending on the volumes and then demote it to Aluminium, then Zinc, then Pewter, so this way I get a lot of uses out of them, I now have one I only use for pewter but had it for years and still in about half worn down condition. At 250C there is very little degradation. I also noticed difference in crucible quality depending on where I bought them. Apparently there is graphite and graphshite... 😂👍
I ordered a gas foundery recently. For the price point you can't go wrong. I've melted some copper and made some ingots. Just haven't decided on what to make yet.
I have melted 3 ingots worth of bullet brass so far...thing works GREAT...just make sure you pour into a NON-water filled surface or it will cause a steam explosion I used an old cheap barbecue pit lid that the legs broke off to pour my mold...and to whack the slag spoon I used to scoop the dross off...much easier and safer and has a wrap around type enclosure so I don't get accidental spills and fires
I received my new vevor electric furnace today. I was dissapointed that i didn't order the new one, but now I am glad to have the old style (type on your right). Once molton metal splatters (much less pours) onto the heating element, it creates a short and has to be replaced. The old style may be a bit slower, but without visible wires, that has to be a plus!
Most definitely keep track of how many uses on the crucible. I work at a professional foundry (stainless steel, aluminum, and titanium casting). Tracking number of melts or number of minutes a crucible has been used is super important. We prefer number of melts, as this catches the heating and cooling phases. If you do time, start the clock when you start heating and stop the clock when your hand can physically touch it again. Second best tip is to baby them! Pretend it’s the egg baby they give teenagers…. But do better 😂 All the other tips are great too! But for safety of yourself (I’m the safety manager of the foundry) and safety of the equipment keep track! PS - if you need advice on PPE let me know.
Would a cast iron pipe/steel pipe with a plug welded on the end and a flange on the top work for non-steel type metals? Since the iron/steel won't melt at the other metals temps...would they hold up better?
@@haydenc2742 yep! We melt most our aluminum alloys at about 1450 F. We definitely use steel this way. Even for our stainless steel melts (a hot melt is pushing 3100 F and a cold melt about 2700) we use plane ol’ rebar to skim the tops. When we accumulate about a softball to grape fruit size slag chunk on top we get a new piece of rebar. For context, we have three 500 lbs melters. But principle is exactly the same. Just scale it down.
Cast yourself a crucible stand that holds them up vertically by the neck, but off the ground, with enough space to load and unload them with the tongs.
I learnt the hard way to always pre-heat your crucibles (As even moisture from the air can be absorbed), saying this when i had money one time i actually purchased a few through a supplier that a big foundry uses and the quality really showed compared to other brands i had used. I have had weird problems with lower quality ones were my crucible wont melt stuff , yet it will melt it metals outside the crucible. Love the videos
That bronze grain can pack in tight enough to crack the crucible as it expands. It's way more likely to happen with softer metals though. Cracked a couple crucibles with lead BBs before I figured out shaking it to fit more in was bad.
I have a similar furnace (for all I know it's made by the same factory with a different sticker) and the instruction manual says to preheat to 300-500C (572-932F) and letting it sit for 5 minutes before upping to the target melt temperature. I don't know if that's for moisture (similar to drying out the crucible in the oven as you mentioned at 8:00) or something else, but figured I'd mention it.
Hey Paul I see most people pour from the furnace instead of lifting to not expose the crucible to too much oxygen . The crucible breaks down faster with more oxygen
Keep in mind that red hot carbon is not like red hot steel, carbon actually grows in strength as it heats up... Now, i`m not sure how it affects both the tensile and the compressive strength, but carbon is not steel nor any other metal, it`s a material all on it`s own... I generally do not cream all over carbon fiber like some fanatics, nor do i like it all that much, but carbon and carbon fiber and graphene among other manifestations of carbon are immensely good at certain things and have some rather interesting property combinations... A crucible may be brittle and relatively sensitive to thermal shock, but it is not weak by any means... Regarding the ball stock or shot that you used, that could very likely crack the thing due to thermal expansion... shot packs up very neatly, even if it is not perfectly round... every little ball is a small impact that rattles the whole column below it and potentially helps some other ball seat better... heat them all up after they are well packed and you have something that is masquerading as a porous cylinder... *edit* You can also plumb argon to the furnace and drastically improve the life of the whole system, especially crucibles... Also helps if you want to melt iron if the furnace can go that high...
I have a way to really extend the life of them. When you are finished casting for the day if you can put that crucible in an air tight container when its red hot and they last way way longer. I have a pan of dry sand with a flat tile of graphite that I set the red hot crucible on. I then cover that with a metal can and it puts out the graphite fire (the crucible is on fire if you look closely). you can double the life of the crucibles doing this. If you don't put out that graphite fire it just burns for a few hours in the furnace after everything has been shut off after the pour.
OH SNAP...never thought of that...I wonder if burying it in a pail of very fine sand (like play sand) after a pour would stop/smother the burn and allow the crucible to cool and slow/eliminate the carbon burn off? I too have just shut down the furnace and let it cool on it's own...I bet just like you said...as the whole thing cools it slowly burned itself out thinning itself...need to check my crucible
Graphite fire? Some wax or oil must have gotten into the graphite. It sublimates at like 700 degrees and you shouldn't see any type of flame. If your furnace is staying over 700 for "hours" you have it ridiculously over insulated.
Now i want a design with a graphite “Core Catcher” so your bronze “coreum” doesn’t flow into your Electronics and instead is contained until it cools off. That and/or it slides to the left onto your desk lol.
that sounds like a good idea! In this case, the "coreum" is caught in the body of the furnace. So it never spills out on my desk, but it very much does wreck the furnace lol
the moisture wicking up from the concrete might have sumting to do with it might need to do a cycle of heating and cooling to get everything out and then check for cracks before using it
For Zamak you could use a cast iron crucible. Maybe that would be a solution at least for that material ? All I know is I don´t want ever to brake the thing while it was molten metal inside.
I love your commentary. Keep up the good work. I store my crucibles in individual padded cardboard boxes (the ones they were shipped in) close to floor level. That way, if Godzilla wanders into my basement (aka me), the crucibles are somewhat protected. 🐲 Cheers from Alaska
I run mine a lot cooler, cause I'm just melting aluminum; but made myself a pretty robust steel crucible to melt in. 11ga walls, and 1/4 thick plate bottom. Feel a lot more comfortable smacking it around to dump the crud out of the bottom too. Have melted about 40# of metal in my little Vevor, and still going strong, though I get it sluffing off a layer of oxide every cycle.
What about using a stainless steel crucible. After watching your video I used the same kind of furnace. I'm researching the idea of using a stainless steel crucible for brass. I don't think I'll ever cash them bronze. But I think you can. More work needed.
there is a guy ive been watching, forget his channels name, who has been melting metal in a microwave, and it seams to work super well. Its most likely what im gonna be trying when i need to cast metal. He shows how to make crucible, and other things needed for the process.
@@PaulsGarage from his videos, it looks pretty safe to me, hes got insulation and what not and can grab it with bare hands and not get burned...... i just found it again, the channel is "shake the future"
If it's the guy I've seen, the crucible gets HOT inside ceramic insulation, while the body of the oven remains at a respectable temperature. Effectively a radio frequency induction furnace.
Had the same when had an electric one. Didn't season new crucible & doesn't like high temps.....especially copper. Destroyed both crucible & machine. Went over to propane furnace & never looked back
2x4 w/ 1" wooden dowels at an inch or two longer than the depth of the crucible (or maybe shorter to prevent stress on the inverted bottom of the crucible?)...set them on like boots, as long as you don't drop stuff on top of them...they should be fine right? Maybe a heat to 100~C for 20-30 minutes before ramping way up to full melt temps? (like the dwell of melting the solder for PCB's on SMD components) I have the same one you have...first heat on mine the solder on the switch inside the main housing melted, instant shut off, no shorts (it had a teeny tiny blob on the switch contact vs a huge honkering one I put back on...make sure no high resistance solder joint, or the high current flow to the element will cause the solder to melt and click...off goes the furnace)
If I had to guess, these do not. Some of them (that one I used a LOT) appeared to be milled from a graphite block. The one that broke was molded, but it looks like graphite only.
maibe you can find an old milk (beer bottle) crate they used for bottles , you can store the tall thin cruisibles in the crate wish should keep them from knocking about (could wrap them in wadded up newspaper to make sure they cannot move inside the hole ) keep them upright and off the flooor itself people allway talk bad about "stuff made in china" but there aftersales is actually pretty good
Half way in, haven't heard your conclusions, but that grain in there expanding almost certainly blew it out. Think about how grains work when packed settled, and beyond their natural angle of collapse? Under your driveway is packed gravel. It was solid before the concrete was poured. Bet yiu it was this. Unpausing... :-)
Related, I once blew up a $1000 metal device using only the compressive strength of thin nylon strand. Took me less than 6 hours. I'll DM you how I did it on discord.
Always be sure to fire a new crucible empty before you use it. Firing it up to full temp and letting it cool slowly while empty will sinter the crucible. The factory is supposed to do that, but don't trust it.
I think these are pure graphite instead of clay graphite. It allows them to be suspended by the top where a clay graphite crucible would break or droop.
It would probably help the oxidation problem for the metal and the crucible. I have a tank of argon but it would be tricky to stick the whole thing inside a giant argon purged box.
I tried this with my last copper melt with an electric furnace and just 'poured' the argon in. I figured at least the argon weighs more than air and would at least reduce the amount of oxygen in both the oven and crucible. I had almost zero slag compared to my past copper melts and the crucible looked good coming out. So... idk? I'll keep trying that.
You overfilled it lol With the grain been so grainy there's no gaps or space for stuff to expand, I've done this with silver :) Don't overfill with stuff that leaves no room for expansion like grain. Just put in like 1/3-1/2 at most then add in more once its molten, in stages. Addign too much will make it freeze... and break again lol (I've broken mine a LOT learning the fun way!)
With bronze/silver temps, i chuck it after 7/8 uses now. With lower metals, dozens of uses. You can measure the internal diameter near the base, then the external diameter near the base to calculate the remaining thickness of graphite to give you a bit of a guide how risky it is. There is a product you can paint over these graphite crucibles to give them longer life, Boron Nitride based, and it works by acting as a barrier between the heat and the graphite, so the graphite doesn't deteriorate into co2 as fast :)In the UK via HSWalsh it's called Crucible Spray - TC0996. I have considered making it from scratch (think pottery glaze kinda process) and experimenting a bit as I've a stack of crucibles I'll never use to cast in but would be good candidates for science without the risk of lava, but the spray itself isn't that expensive, so maybe i'll ge tthat first and use it for baseline comparison as i fuck around xD
After I used my graphite crucible just once it was 'pitted' all over, which is why I bought a gas furnace because I could see the electric one costing a lot in crucibles (plus they they don't hold that much molten metal). It's been a while since I watched your videos (thank the RU-vid algorithm for that) but don't you make things out of ceramic??? I recon you could make a lot of money by making ceramic crucibals for these electric furnaces because the graphite ones suck.
I'm guessing the ceramic becomes more molten as its heated and if you suspend it from the neck of the crucible, it'll break or elongate. You'd need to make a plinth.
@@ryelor123 There was a small Polish company actually sells ceramic crucibals for these, so I'm not sure that is the case. Unfortunately they were not exporting them. It's worth an experiment for those that have the ability to make them.
Scary part...spilling molten metal on ANY concrete surface...the moisture trapped in the concrete below the molten metal flash steams and POPS in a molten metal "explosion" NEVER pour molten metal anything on concrete...always set the mold on a surface covered in sand or dirt or even a dry wood (that can be extinguished easily)... I used a lid off an old busted back yard barbecue pit/grill to pour my molds and smack my dross spoon on...to keep the super heated materials away from any moisture (and provide a pretty decent heatsink in the process...
@@PaulsGarage It's especially fun when it's the rocky ground itself that is exploding under the fire. Happened at the next camp over to me one time. Hell of a bang, lots of swearing, so we went over to see what had happened. Their campfire had exploded (rather the ground under it had) and blown bits of campfire all over their camp. Thankfully no harm done, except for the shock.
Don't leave them in the furnace running red hot...apparently the crucibles "burn" away due to the oxygen reacting with the carbon (per the video's explanation)...I think I might start burying mine in fine play sand to reduce the availablility of oxygen to it while it cools...to smother the reaction and to allow it to cool "slower" What is the melting point of silica (sand) compared to metals that would melt in the furnace/kiln....hmmmm [sand roughly 1700°C, temps the furnace can get to is MUCH lower...]
The originals have a solid ceramic shell...the newer ones seem to have slits in the shell, I guess for faster heating...but susceptible to shorts if/when the crucible cracks and dumps the molten metal to the bottom of the shell
