9 Things I Didn't Know Before Building a foundry: Casting 101

these are the top things I wish I knew before I built The Foundry first off this is not a Foundry this is a furnace this is a Foundry a whole messy place that's a Foundry this is a furnace this is The Foundry it's one thing I didn't know when I started that was a bonus on to the real things first one aluminum cans are trash controversial statement now a lot of you like me probably have seen a million YouTube videos of people taking aluminum cans they melt them down pour it out make an Ingot of aluminum and you're like that's so cool yeah it is melting metal is fun that's why we do this however aluminum cans have a lot of paint on them plastic coating and they have a lot of fumes so if you're doing that a lot you're breathing in some noxious fumes and it's not healthy it also causes a lot of Dross it's a mess for your Crucible I'm not saying don't do it by all means I think you should know what it's like to melt the can I'm just saying be prepared for scooping a lot of draws and don't stand downwind but also it's important to note the quality of aluminum is not great and that goes for any extruded aluminum license plates landscape edging wire these forms of aluminum were not made for casting so if you're making something important like parts or works of art not going to be as detailed it's not going to flow as well some people will try to clean the aluminum with something like borax it doesn't change the Metallurgy of the aluminum casting aluminum is alloyed with different elements people will add elements like metallic silicon to the metals to help it flow better and give it better properties for casting a common source that's alloyed for casting are tire rims but it could be engine parts or anything that's been cast before it's going to be a lot higher quality metal if you're going for Quality Parts that's one thing I didn't know you can buy metallic silicon and try to alloy your own aluminum but in a backyard setting it is more difficult but again if you like experimenting you want to have fun you can try adding silicon so if you want to melt cans go ahead do it just kind of understand what you're getting the next one is a difference in Sands green sand versus petrabond which one is better what's the difference green sand is very simple it's just bentonite clay fine-grained sand add water to it so it can compact and that's all there is to it it's generally cheaper but what I didn't know is that it's more of a pain to deal with for small scale operations for one this green sand is dried out now in order for me to get this workable so I can use it in casting I have to break it up so it's nice and friable and get it all evenly wet so what I used to do is I put it on a board and I would slowly crunch it by hand spray it crunch it knead it so it was evenly moist and it was a lot of work typically operations that use green sand will have a mulling machine it's just a drum with a roller that helps smash the sand mix it up evenly so you don't have to deal with your elbow grease also with green sand and part of what gives it its strength is the pressure so molding machines typically have a heavy wheel putting a lot of pressure down to kind of stretch the clay and that'll help give it its strength so it's hard to do by hand you can do it but it's harder now with Petra Bond it's an oil-based sand it's a fine-grained sand with a bent tone not the same as Bentonite Bentonite tracks water Ben tone is specially formulated to attract oil put oil with bentonite it's not going to be the same and tone is typically used in oil fields for drilling mud other than that it's kind of hard to find the nice thing about petrabond doesn't dry out so for small scale operation it's easier to store and then when it's time to use it I don't have to adjust the water ratios I don't have to knead it I can just take it out it's friable it's ready to go so if you're not doing a lot of it I think it's worth it to invest in some petrabond or oil-based sand the drawbacks of petrabond the oil Smoky so when you cast your metal you don't want to breathe the oil films kind of stinks but other than that I think it's my sand of choice which one is better quality it doesn't matter what matters is the grain size of Sands so if you have a fine grain sand you're going to get more detail horse or grain sand you're going to get a coarser casting regardless if it's green sand or petropon that's another thing I didn't know some people like to just stack their ingots like treasure that's fine my ingots are always pretty ugly because I know I'm gonna use them later for art projects if you decide to go beyond ingots and start making more parts or art you need to decide am I going to do sand casting or lost wax casting or lost pla two different styles two completely different setups for sand casting this is a flask it's just your wooden box at the bottom side that you drag the top side we call it the cope usually there's some guides to help it lock directly in the right spot pack it full of sand and that's all you need good for doing things like sharp teeth or simple shapes like a doorknob but if you want to do more complex pieces like this bronze Fisher skull a lion an elk baby Yoda or even a Donald Trump gonna have to do investment casting takes a lot more of a setup to do investment casting you're gonna need a kiln for wax burnout you're gonna need a TIG welder or get really skilled at brazing I think a TIG welder is better cheap set is going to grun you about a thousand dollars for a flask you're gonna need some kind of Steel preferably stainless steel or a fancy perforated flask for vacuum casting you can use any kind of Steel but regular steel will oxidize scale off it's not going to last nearly as long as stainless and it can be any shape as long as it holds the investment the investment I use is ultra vest from Ransom and Randolph I get it from Rio Grande jewelry supply it's a high quality material and it's porous so I can use my vacuum casting with it some people will try to cheat and use plaster of Paris the plaster of Paris isn't formulated to withstand the heat moisture releases at about 400 Degrees which causes it to crack people will mix sand in there to help give it a little more porosity to try to prevent the cracking and you can do it but it's not going to be as high a quality if you want high quality products you have to use high quality materials and if you're going to take the time to do the wax chasing and everything that you need to do for lost wax casting may as well use a high quality product so sand casting is easier cheaper but you're going to get less intricate projects loss wax casting or lost pla you're going to need a little bit more setup for that you can also do ceramic slurry with loss wax casting that's not something I've done you want to know about ceramic slurry learner burn Studios is a place to go you can teach you way more than I can it comes to that another thing I didn't know about is metal shrinkage now one of the things I really struggled with metal shrinkage with was the golf ball trophy you can see on this attempt of golf balls around the top of each one the metal has contracted and shrunk in because when metal is hot it's it's expanding all atoms and molecules are running racing around and as it cools down it contracts that being the case every time you lay out how your metal is going to enter to your piece you have to take into account metal shrinkage now in this case I would need a reservoir of metal on top because as things cool heat rises So in theory the last part to cool down is going to be the top so as all this lower part is shrinking and Contracting I need a reservoir for the metal to draw from so I don't have contraction in the piece I have contraction up in the reservoir because that's the last thing to cool it's for that reason a piece like this is cast Hollow which is why you need the welder to weld pieces back in place if you look back when I tried to cast the bear I tried to cast it solid and I had a tremendous amount of metal shrinkage up on top since then I've been casting all my pieces Hollow and that's how it's done professionally as well you want to do art projects you have to learn to cast Hollow But Metal shrinkage is another thing I had no idea about for those who just want to make ingots and muffins out of metal you melt people will ask do you need to quench it no you see a lot of YouTube videos where people quench them it's just for the visual effect there's no reason to quench in Ingot unless you like to see things Sizzle then go ahead and quench it doesn't hurt it you just don't need to do it another thing I didn't know was concrete and molten metal do not mix for the same reason you want to heat up your Ingot trays because if there's moisture in there you can have an explosive expansion of steam inside concrete there's moisture hidden there so when you have hot metal go on that concrete you have what's called spalling it's just like a popcorn kernel the moisture inside the cement turns to steam and enough pressure builds and you can have explosions of concrete not only is it kind of dangerous gonna ruin your shop floor so ideally you want to cast on layers of sand it has to be thick enough that's still not going to heat that concrete up to that flash point level or what I've been doing big sheet apply with plywood will burn but it's not going to explode unless you have a lot of metal that's going to run off the plywood my projects are usually pretty small that being said with moisture sure most of you guys know you're supposed to heat up your molds before you pour molten metal because any moisture that's trapped in there once that molten metal hits it it can Flash to steam and that can be explosive so you want to heat your molds up at least to above boiling temperature so the water is all gone you do not need to heat your molds to Red Hot in fact you shouldn't heat them that much you just want the water to be gone before you pour the metal in there every time I cast I wear a face shield just in case I have a little moisture in there so always be cautious of moisture heat up your molds keep that metal away from concrete that's also something I didn't know before I started another one is the difference between brass and bronze both are very common casting metals and both cast very well with brass it's easier to find scrap pieces that you can melt down if there is a piece like a steel screw in there or something inside the steel will float on top of the brass and you can scrape it off the top but with brass it's primarily copper and zinc zinc has a much lower melting point and a much lower boiling point so when you melt brass commonly see white smoke coming from your furnace that's the zinc burning off so every time I melt brass I wear a respirator because if you inhale that white smoke you can get what's called metal fume fever it's not going to kill you but it'll make you sick with bronze it's primarily copper and silicon most bronzes have very little or no zinc so you don't have to deal with the zinc boiling off and also when you get into welding your piece it is much easier to weld bronze than it is to weld brass because of that zinc once you get the weld bead going immediately the zinc is burning off at those welding temperatures so you get a lot more porosity and a lot more just a lot harder to weld brass welding bronze is like a dream so in all my complex sculptures I use silicon bronze it's something simple like a shark tooth I'll use bronze brass or whatever just depends on the piece so it's not that one's good better or best they're just different and that's something I didn't know before I started another thing I didn't know about was hydrostatic pressure that played a part when I made the bronze sword I cast a sword in this orientation and when I did the tip of the sword was like five times thicker than I thought it would be I didn't know why later on I realized that when you have a column of metal putting so much weight down there's so much pressure at the bottom that if your sand isn't tight it'll force apart and misshapen your mold it's also super important to keep in mind when you're sand cast you build a box like this you need to have clips that lock it in place or put a lot of weights on top if you're casting something with a big surface area or a lot of metal if you don't when you pour the metal in it'll float these boxes force apart and your metal is going to run out the side that was the case when I tried these shark teeth they were orientated like this when I poured the metal in it floated the top part of the Box off and caused a cope and drag to separate and it all ran out the edge of the box I didn't have enough weight down on out now this is still a work in progress but hydrostatic pressure is going to play a part here this is my Sagebrush lamp with this big funnel if I fill that with molten bronze there's going to be a lot of pressure that'll help push all the air and everything out it'll help push the metal into any small place but because there's so much liquid pressure sitting above there's a lot of weight being put down at the bottom and the pressure is going to want to blow out so I need to make sure that I have this secure so I don't have that blowout problem so be sure when you're casting you keep hydrostatic pressure in mind that's something I didn't know about when I started and lastly don't use salad tongs to lift your Crucible a lot of people see the king of randoms videos and it's good because it makes people realize that they can do this stuff in their backyard but he teaches a lot of bad habits one is how he handles his Crucible do yourself a favor and make a ring it's not hard your Crucible sits inside the ring you can pour it out you can add safety clamps on there so you can flip it all the way upside down but if it's it slow enough I can still get everything poured out with just a ring when a crucible is hot it's at its weakest point and you don't want to be putting a lot of sideways pressure on the walls you want something that's going to cradle it I used to take tongs like this and use it to lift The Crucible Out of the Furnace don't want to do that I used to hold it like this and try to pour it very dangerous make yourself a pouring ring and make yourself some lifting tone these are tools of the trade to keep you safe don't skimp out on it hopefully you found some of those things useful if you did please hit the Thumbs Up Button if you have any issue with what I've said or want to add something of your own feel free to write that in the comments I'd love to read what you have to say don't forget to come on back for some more videos thanks for watching

Channel: Lundgren Bronze Studios

Views: 703,282

Keywords: Backyard foundry, Beginner casting, Beginner foundry, BigstackD, Bronze casting, DIY casting, DIY foundry, Forge, Foundry, Ingots, Metal casting, Metal casting 101, Molten aluminum

Id: HYGBH33dnsc

Length: 15min 36sec (936 seconds)

Published: Sat Jan 14 2023