DIY Foundry At Home
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- Опубликовано: 24 мар 2022
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We needed a way to recycle the metal scrap from our DIY machine shop, so we developed a simple workflow to create a foundry at home for super cheap. Our ultimate goal was to melt copper scraps from our CNC machine, and the process was definitely very challenging.
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Sodium Silicate would have been a better material for the furnace. The mold could also act to connect the CO2 bottle for hardening.
Id like to see more work with 3D printing in wax. This would allow for lost wax casting.
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@@glyph241 😂 welcome aboard
also you should be carfule when melting brass since it contains zink and when zink gets heated it releases a harmful gas
Concrete can explode when heated similar to rocks so be very mindful of that if you continue to use it. I would recommend redoing the foundry with refractory cement to prevent explosive accidents. Preheat the molds before pouring in the molten metal. And finally, instead of the small propane cans you should use the large BBQ canisters and build a larger single torch that heats the crucible in a cyclone from the bottom. Also, palm sander on the side of the container can help settle the cement into the voids and remove air bubbles. Commercial concrete pours use vibratory tools to get the concrete to settle around rebar
Also, if you add the water on top of the plaster/concrete in 2-3 times while mixing, and not the plaster after the water, it's easier to avoid lumps.
Regarding the concrete, adding more water makes the concrete weaker, so the indicated value on the package should be followed (which depends on the amount of cement in the mixture). As a rule of thumb, it must be wet, but water should not end-up laying on top of the mixture.
Thanks for your input. This was our reason for not adding extra water, to reduce the likelihood of the cement cracking. I hope you enjoyed the video regardless 😊. Cheers, Dave
@@ActionBOX Best material I have found is a mixture of Soft pink fiberglass and Clay. It turns into sheets that I always wrapped around materials but either way the mixture could be ripped up and stuffed in a mold. You let it dry then turn on the forge to fire the clay and it works great. There is a commercial product which is similar going by the name of Kaowool. For your setup here I personally think even a clay/sand mix could be used but the fiberglass is night because it makes it light weight and prevents it from ever cracking in any substantial amount acting like rebar yet still becoming part of the ceramics as its fired. Been tested and it works better than commercial firebrick matter fact.
The plaster of Paris and sand is basically refractory. I've used it for foundries for years and it's never even cracked
@@ActionBOX Another safety note for you: be careful when working with molten alloys. Brass is an alloy of copper and zinc. Zinc oxide fumes will make you sick and that stuff is a fine particulate (it's the white smoke that would have came off the brass). At minimum you need to make sure you're upwind, but i'd say use a respirator/n95.
Also, as a safety gear suggestion: Get a welding jacket, face shield (a basic welding helmet will cover this and allow you to get a good look at brightly glowing metals), welding gloves, wear jeans (anything made from natural fibers. synthetic fabrics will melt to your skin. It sucks, avoid it), and pull the cuffs down over your work boots.
Molten metal is one of the more dangerous things you can work with if you don't follow the safety steps, as you guys almost learned with that pop you had. I'm not saying don't keep at this, just hoping you do a little more research on the safety front next time. It's some time vs possibly losing an eye or worse.
If you're ever casting anything besides bars for instance. That little pop in an ingot mold isn't too big of a deal thanks to the safety glasses. In a casting mold (enclosed mold) the same mistake would lead to a much more... vigorous pop to say the least.
Couple words of advice:
Never get your crucibles or graphite wet. In fact, always hit your mold with a torch before you pour. Any moisture immediately evaporates and as you fouund can be violent.
Use flux on your molten metal. Either a dash of borax, or a hint of boric acid.
Once molten, get a graphite stir rod, hit it with a torch, then dip it into your molten metal and drag it off to the side
Your black spots are more than likely impurities. Always use 1 crucible per metal. It could also be from water/moisture in your mold. Always preheat the mold.
You have bubbles and holes from the casting process. It may be too cold like you suspect, moisture, impurities, etc but, any stock you purchase isnt just cast..its cast into a billet, reheated, and run through various mill stands while red hot and quenched with sprays at very precise speeds.
I do automation for steel and aluminium mills (including casters) and have been pouring silver and gold jewelry in my garage for 2 years. Ive played with torches and I’ve concluded for casting, using even a cheap 300$ amazon melting machine is the way to go. Melts copper no problem. Thats all we use for copper, bronze, silver and gold
Literally never had a crucible break/crack/explode and I have dropped them white hot into water.
Person that knows what they are saying, great info...-ER
Where can I get an induction Melter that can handle 4 Kilograms? biggest I've been able to find is 3KG (3KG gold rating, but I want to use it for aluminum.)
The discoloration of the brass bar is due to the separation of zinc and copper during the smelting process. Copper and zinc have very different melting temperatures and densities. To minimize this, stir the molten metal thoroughly prior to pouring.
Awesome, thanks.
actually seems more useful to use this to separate the copper from the zinc, but relying on this mechanism might need 4 or 5 smelting cycles to fully separate
For the aluminum bubbles at 21:15, aluminum absorbs hydrogen as the temperature increases. Typically you want to monitor the temperature to not get aluminum too hot so it doesn't absorb the hydrogen. Once you poured it and let it cooled, all that gas starts to come out of the metal which causes those bubbles
Which Temperature are we aming for?
You can degas the aluminum with boric acid or salt.
The small bubbles in copper, brass and I am assuming aluminum can be from oxygen or hydrogen.
Hydrogen is usually introduced due to hydroscopic actions of refractory or moisture in scrap crucible, etc. Can also be introduced from fuel used to melt but I have no experience with this as have always been around processes using electricity.
Oxygen comes from exposure to atmosphere during melt as well as moisture or contaminants in scrap.
Once in molten metal gases become suspended in the liquid, as molten metals cool the gases drop out of suspension and cause the bubbles.
Oxygen - cover molten metal with a blanket of graphite to prevent absorption, deoxidize using copper phos or boron.
Hydrogen harder to get rid of in hobby foundry... but technique is to bubble argon or oxygen through molten metal and then deoxidize.
For the aluminum smelting, when I did a project in school, we added Flux to the melted aluminum and then scraped a bunch of slag of the top to remove impurities. Not saying it's your answer, but it might help. Got a chuckle out of the sand is cheaper than dirt as well 😆
Thanks Jonah, we try to throw some jokes in to make it more entertaining 😜. Glad you liked the video, and thanks for your support. I look forward to your reply in our next video 😃. Cheers, Dave
What flux did you use?
@@SandeepKumar-jj7zi I honestly do not completely remember as it was some time ago. I do remember it was a white powder, so it could have been borax?
@@SandeepKumar-jj7zi Try borax. Get at Wally World.
20 Mule Team Borax. My father initiated me into the ancient arts of Blacksmithing and decorative ironwork and knife making. Our church was the old pole barn, the altar was the glowing coal forge, his pulpit was the anvil, and our cross was the hammer and tongs. Im 36 now and my arm is still sore from cranking that old buffalo blower. But i got so good that dad could set me like a thermostat. I love that man. We used 20 Mule Team...religiously lol. Metal working is rewarding, hard and dangerous but rewarding. More than almost anything. I just found this channel i believe i will watch another of your videos. I enjoyed this one quite a bit. And everyone in the comment section are intelligent, experienced, helpful and supportive. That's pretty rare. Keep up the great work!!!
The reason your cast iron ingot mold failed was because you cooled it. Metals become harder and more brittle when rapidly cooled from extreme temperatures. Further, the outside cools faster then the inside because it comes in contact with the cold water first, so the mold shrank in around the ingot and basically squeezed tighter around it, likely deforming or cracking the mold before it got a chance to cool down inside and release the ingot. Def would recommend just waiting for the copper (or whatever material you're working with) to freeze up on its own and then a simple tap should knock the red hot ingot out of the mold. After that you can quench the ingot itself and your molds will last a lot longer!
This is the stuff that makes youtube relevant.. Thanks for the effort
I used to mix plaster every day for 2 years for casting molds. If you want good smooth result with plaster, run your plaster through a flour sifter and use a whisk to mix it. Pick up the container a little and rattle it against the ground. Pour, then rattle a little more. Also use a separator whenever casting plaster, a thin coat of a little soapy water mixture is just fine.
Awesome, thanks for your expert advice we’ll give it a try next time we mix plaster. Cheers.
One key thing to do before pouring molten metal into an ingot mold is that you heat the mold up right before doing the pour. This eliminates any possible water/liquid still in the mold and makes for easier removal when cooled. The other thing is to remove the slag from the top of the molten metal. This allows for a more pure bar when poured. Note: your funny shirt is just a line of G-Code for a CNC machine ;)
Thanks for your comment. As we demonstrated in the video on our second run, we heated up the ingot molds to be red hot, so I can definitely agree with that comment. As per our shirt, that G-code represents “home” for a machine. See if you get it now 😃. Thanks for your comment, Dave
it happened to me before I didn't leave it heating long enough and bam I had liquid copper flying around the place turned my lesson that day
There's no place like 127.0.0.1
The clip-art of a CNC machine on that t-shirt is the exact one seen in a Forgotten Weapons thumbnail
Solution for lumpy plaster.
Plaster needs to slake in water for a few minutes BEFORE mixing.
Slake means to add the plaster slowly to the measured water. Let it rest and in 2 mins the water will wick to the top of plaster mound. Then stir. You’ll find that it is lump free and free flowing.
I see that others have mentioned that you should slowly bake out the moisture in the cast part so that it does not pop or explode. When building small foundries I always set the flame at an angle so that the flame works around the edge as it goes up. The laminar flow will help. Also, try printing the molds with a "draft angle" of about 6 to 10 degrees. You might be able to print the molds so that they are reusable. Also, you can use a saber saw (without a blade) as a vibration device to shake out the bubbles. Last, using the same crucibles for aluminum, copper, brass, etc. It will contaminate the different metals.
Using a saw without the blade is one of those simple, obvious solutions that never would have occurred to me. Thanks!
Comments like these makes me wish that I could like more than once. The point about the moisture is such an important point. I've seen the results of gas explosions and metal before and it's both specatacular and terrifying. Reusing the mould is a great idea and the sabre saw idea is both simple and absolutely brilliant!
@@Gangdyret and @Michael Merrell, the saber saw idea is not mine. It is rather commonly known by people that use molds for concrete, plaster, epoxy, and other fluid materials. I do appreciate the kudos though ;-) Yes, "candling" the kiln is something that we do in ceramics all the time -- basically turn on the heat on low so that it drives out all the moisture before ramping it up fast. BTW, ceramics are very sensitive to changes in temperature. Even after it is dry, if you ramp it up to fast it will warp or break. Many of the techniques used to build and fire ceramic kilns will work just as well for metals (with metals you can ramp them a LOT faster, and push them in ways that you cannot for ceramics). The "draft angle" above is standard mold making techniques. If you can find old metal foundry mold books at the library, you will learn a lot of useful stuff. Hope you enjoy!
For mixing, you want to use a paddle mixer, not a paint mixxer. Paddle mixers work well for drywall compound, plaster, cement, etc
Good to know. Thank you 😊
try adding the water sliwly to the powder while stirring, as done in cooking
So many videos out in YT land that say to heat your molds to remove water. So glad you showed the clip of why this is important.
Also, removing the ingot from the mould before dunking the ingot into water is much easier. :)
Nice video, great crucible. 👍
Brilliant use of 3d printing for something more than just printing toys, Thanks for sharing.
You need a hotter burning fuel for the copper.
Also, when casting copper and its alloys, coat your mold's surface with a carbon layer (copper loves bonding). If you don't know hown to do that, coating with grease or oil will do.
Degas aluminum by stirring potassium chloride into the molten metal before you pour.
There are a lot of great videos on YT for casting.
Love the constant “dad” jokes! You hereby worthy of a sub!
For working with plaster, pour plaster in water, not water in plaster, and let it dissolve over a minute. It will all sink into the water without clumping and with fewer bubbles.
If you change the angle of the torch tunnels to anything other than straight toward the centre for a swirling effect, and the internal ribs from straight up to an upward spiral, you'll get a lot better result.
I can confirm this!
That's what I was thinking when watching this. Most of the designs I've seen have the torch mounted tangential to the furnace/crucible walls to create the spiral you're describing. With a gap just wide enough to be able to lift the crucible, the heat is applied more uniformly across the crucible. Seems like a lid with an opening the size of the crucible, with a gap between the crucible and lid, is a common thing to balance air flow with retaining heat.
Try MAP gas. Yellow can. Should be on the same shelf as the blue ones ya got from Home Depot
Thanks for the suggestion. We saw it but it was $12 instead of $4 and we wanted to keep it as cheap as possible. Knowing what we know now, it’s exactly what we need to help with the copper melting. Thanks for the input 😊.
I'm so glad you guys were wearing safety gear.
Oh, removing the 3d printed mold is fairly easy - put it in the oven for a bit so that it softens - I user 120 degrees Celsius. If your plaster can't handle that, then your in for further problems...
Omg, that’s so smart haha. I wish we could have asked for your opinion before making the video 😜. Thanks for watching. Cheers, Dave
I'm a new subscriber to your channel. I would recommend a couple things dont add foreign materials to the crucible also heat the mold up to remove any water. Also scrape stag from the top of the molten metal. I learned alot of stuff from a youtuber called bigstackD casting. He does so much casting and really helped with my casting.
Awesome, welcome aboard and thanks for your detailed comment. Many people have mentioned that channel already so we will be checking it out. Cheers.
I used to melt down and recycle a lot of aluminum, and besides fluxes which you can buy, another industry trick is to have a cylinder of "dry nitrogen" and just bubble it through the molten aluminum right before pouring to de-gass it. Also, molten metals are not chemically neutral, they will react with things like steel (think of them like a super hot acid), that's why crucible materials are so particular. Though the rapid erosion of your first crucible probably indicates that the early torches were not burning a proper mixture of gas and air and were producing an exhaust that was oxygen rich.
I wou suggest putting the plaster/sand mixture into a vacuum chamber once it's poured into the mold, this will eliminate air voids and also will remove all moisture (water) from the mixture, so it wont explode when heated and most likely won't fracture either
Key to mixing Plaster of Paris is to add plaster slowly to water, allowing plaster to fully whet before adding the next layer of powder.
Hank Hill would be so proud of you for such an innovative use of propane and propane accessories
Lol
The small pores in the aluminium bar are most likely caused by hydrogen in the melt. This is very hard to avoid, because any impurities, mostly aluminium hydroxide and other stuff from the passive surface of aluminium parts, react to hydrogen as a side product. Hydrogen can also come from moisture in the air and from the organic gas that is used as fuel (propane contains hydrogen and reacts to carbon dioxide and water when burned). In big foundries they can use processes like vacuum melting and electric heaters, which is hard to do at home, even harder if you want to do it cheap. There is the possibility to use additives or melting under a flux, but I really have no knowledge about those.
For the big bubble in the copper bar, this looks like a blowhole that is actually still caused by water vapour from the mold. I don't think this is a misrun because how should that happen in an open mold. It could also be from hydrogen in the melt reducing copper oxide that is also included in the melt, but i doubt this would produce such a big bubble.
The only way to fight those things is drying the mold and keeping it hot for the pour to avoid misruns and cold shuts.
This comment was very detailed. I feel smarter after reading it. I appreciate you sharing your knowledge, and I will give your idea a try. Thanks a bunch 😃, Dave
@@ActionBOX Haha, thanks. I think talking and explaining a lot is a perk that you grow with being a teacher 🤣
Another way used in the aluminum industry to get rid of those hydrogen bubbles is to inject inert gaz (Argon for ex) in the molten metal, and steering it for better results... Also, you have to keep your metal at the lowest temp (around 680°c or less)
Fun fact: even in high end aeronautical parts, there is to those "bubbles", just smaller than your part.
I don't know much about copper, but this cavity looks like a "shrinkage restrain" for me (the metal have to shrink while cooling down, and to do so, it shrink a the last hottest area of your part. The bottom of it, in contact with the graphite in this case)
French article about hydrogen porosities in aluminium (in french, sorry. But with nice pictures!)
metalblog.ctif.com/2019/01/21/le-degazage-des-bains-dalliage-daluminium/
@@charlesvanderlinde5506 I also read about the argon, seems interesting.
However, I don't think the big bubble in the copper is a shrink hole, its a little big for that small bar and also it does not seem to have a cristalline inner surface. But what do I know, I have no real experience in casting, only a little material science 🤷♂️
I was going to comment the same thing. Aluminum foundries will add flux then bubble argon to bring the dross to the top, remove it, then vacuum to remove hydrogen. Before it's poured into a holding furnace a sample is off gassed in vacuum chamber then cut in half to look for those bubbles.
With brass, be careful not to over heat it, white smoke coming from brass is the zinc evaporating which is also very toxic. Use a preheated steel spoon (few secs with the blowtorch or on top of the foundry should do, doesn't have to glow red) to remove the slag on top in your crucible, if you collect a lot of slag you can eventually melt it all down to extract more metal. And if you ever find the crucible sticking in the furnace, put cardboard under the crucible, will create a carbon layer preventing stickiness.
You can use maybe 5-6% more water in your cement to make it pour better. When it cures a day or 2, run it through a couple of 100-150C heat cycles before melting metal in it. Pure portland with perlite is better than gravel mix. As for plaster of paris, you can get more working time out of it by mixing outdoors or using cold water. Once it produces heat, you have about 30 seconds before it's unworkable. Also, use perlite in the plaster instead of sand. Good luck!
I'd use an ordinary kitchen whisk to whip the lumps out of that, taking care not to whip too much air into it of course. Whip it dry first, minding dust of course. That'll help a lot.
Slowly sprinkle plaster evenly on the surface and let it sit for approximately 1 minute. You'll notice that it mixes much more evenly when you use this method. If you have a vibrating hand sander you can prop this on the table and use it to vibrate your plaster allowing the air bubbles to come to the surface. You can alternative use a degassing chamber to remove the bubbles from the plaster, but you'll have to be quick when doing so.
I wish to add, when melting aluminum, don't use any extruded aluminum scrap, for some reason it doesn't make ingots that can be machined
So for the small bubbles in the alum you need to degas the hot metal. For that you use potassium. What I use with mine is Light Salt. You can get it at the grocery store. I then make a table spoon pill out of alum foil and get it to the bottom as fast as you can.
Also you want to use flux with all 3 metals. For the flux you will want to use Borax that you buy at the store to clean your laundry something mules in the US.
For a cheap refractory look for portland cement, perl light and plaster. You have to play with the mixture but it works up to copper.
Ooooh with all the scrap copper wire, and my collection of aluminium heatsinks, I'd love to use this mold :>
Can't wait to try this myself!!!!
Sweet, be safe 😃
melting brass is one of those things to make sure you're doing with a respirator! Looking into a proper burner to melt will probably save you money in the long run as well as then you can use large propane tanks instead of the small disposable ones and last but not least angling your flame so you aren't putting a hot spot on one specific location on your crucible will probably help it last longer. Interesting project for sure though.
This all makes sense, thank you for your input. We were using respirators and did notice substantially more fumes from the brass. I assume the other metal fumes are also bad??
@@ActionBOX it's mostly the zinc in brass that's the issue, burns at a low temp and causes awful side effects. It's shown by that white fume looking stuff when you are heating the brass, probably a sign you are getting it a bit too hot.
@@BlacksmithGen thanks for your knowledge. This helps a bunch. I probably won’t be playing with brass smelting anymore.
@@ActionBOX that's probably for the best, if you want more information look up metal fume fever, also called zinc shakes.
A wire brush will take care of the discoloring on the outside, Using Borax into the melted metal will de-gas the metal and help prevent bubbles, and scrape off the dross before pouring, and lastly heat the molds close to the metal temp before pouring will make for a smoother finish. Try it. You will like it.😁
Oh, PS I would love to have the 3d printer. Mine just crapped out the mother board when I tried to flash upgrade it. Thanks
Thanks for your input Dave, I’ll give it a try 😃
Useful tip.. Use Mapp gas(yellow bottle) instead of propane. Much hotter flame!
pro tip: make the four parts key together! It would make it easier for people to glue them together perfectly!
Great idea, thanks for posting.
I like the information that the video provide. Thank you for showing things that when wrong I feel like there a lot to learn with this video. I like that you explain why certain things did not work.
Thank you for sharing. Please be more careful when working with hot metal.
This is a wonderful teaching resource. Thank you so much.
if you do not want the furnace to break, just put the reinforcement in the casting, for example, I used copper conductors. of course, cracks will appear, but the furnace will not burst
Add flux to get rid of the bubbles formed by dissolved gasses coming out of solution as the ingot cools. The flux goes into the molten metal before the pour.
Always heat the mold, it’s easier to get a good shape even when is not wet
Putting in some steel wool into the plaster helps with the life of the foundry
fascinating. I'd love to try casting metal. If you make another foundry in the future, you might have a look at a plaster-cement material called Ultralcal 30. It should be much better than plaster of paris, and easier to pour than pure concrete cement.
Awesome, I’ll have a look. Thank you 😊
For mixing, it's better to start with the water and add the plaster (slowly and mix in between) + paddle mixer
Also, a lid on the foundry will help immensely
The black material on the copper was just an oxide of copper. If you dunk the ingot in water when still extremely hot, the steam created at the surface will blow most of the oxide off
cool video!!! im a jeweller and removing the slag off the top of the crucial before pouring is essential and will help get much much cleaner bars without those bubbles, well worth the 4 second investment of time, can use a stainless steel spoon or similar.
WELL DONE! Keep this up! As a fellow casting enthusiast, here's the notes that I'd add:
1) the mixing of the plaster of paris is usually done with some version of the paint mixer as you wound up doing, but there are a number of specialized drill attachments for this
2) there are a lot of people that use perlite to make these sorts of stoves because of it's high temperature insulation properties, that may make a good replacement or addition to the sand
3) you learned this the hard way and well done learning it at all, any moisture creates a danger, casting on a concrete floor is regarded as excessively dangerous and the recommendation is to cast on a sand-covered floor because any spilled metal causing the moisture in the ground to boil, can not make it pop and throw the molten metal, as the sand does not let the pressure build up.
4) you can probably make a very good ingot mold out of green/casting sand, or a sand that is mixed with a specific amount of clay so that it will clump to a shape and hold that shape well, enabling casting. I could see something like a frame with the end of a board stuffed in being "the ingot" in the shape of that end of a board, for example.
This has been my favorite comment so far. Thanks for the informative yet positive content, and thanks for the enlightenment 😃 cheers, Dave
Sodium silicate also known as water glass mixed with sand would be a better mold than green sand unless you are ok with making a new mold every time. Otherwise some store bought refractory cement or insulating firebricks clamped together (not gonna be smooth though)
My foundry is made from sodium silicate and sand. It's basically just lye drain cleaner and silica gell (crystal cat litter) water and sand.
Despite the concerns of explosion due to water, you probably want the concrete mix to be soupier when you make it, this will help it settle and prevent it from cracking or crumbling in the future. I'm not sure exactly how much extra water effects its likely hood of violently cracking under heat but i know a lot of people use concrete that is fairly soupy for forges, so i can't imagine it's that common.
mix the sand and plaster before adding water, it makes it way easier to mix, and if you can get some fiberglass or carbon fiber to add it will make the end product more resistant to cracks
use cold water to slow the curing time of the plaster so you have more time to mix and apply it. for the big version you can add some wire mesh to increase the strenght and integrity of the foundry on the long run
These are great tips. Thank you
Adding the plaster slowly to the water while mixing might help with eliminating clumps
Seems to be a common answer so it must be correct 😃. Thanks for sharing with us
This is great, love the testing procedure you have done to get the final results! Actually looking to build a foundry so this might have come just in time!!
Really cool!
But would it be possible to heat it electrically? In my opinion that would be even more flexible and cool
It is. We may try that in the next version of the foundry. Cheers
That's called a kiln. Otherwise you can use a welder or microwave transformer attached to a graphite rod to form an arc furnace that can melt steel. The king of random and Ave have videos on diy arc furnaces. I've been wanting to try it but steel seems to spatter a ton when molten.
for the platic mold. Increase draft angles and mold release? Ofc, you always get some mechanical lock from the ribbing if you don't have a way to smooth it before sealing with mold release. perhaps make it multipart mold with registration tabs. ... But the printer is nice because destructible molds are useful for one offs.
Mix the sand and plaster of paris together first and then add water in increments. That way the sand prevents d plaster from clumping.
Awesome, good to know. Thanks for your input Hollee 😃
This is fantastic research and documentation! thank you!
BigStackD and ArtByAdRock need to see this IMMEDIATELY. I would love to see them riff on these concepts, even as they do their own things.
Sweet, Hopefully they have some good stuff to say about this after they see it 😁.
Collaborative Development FTW!
love the idea of printable furnace, just watch when melting brass, the yellow fluffy stuff that you saw is Zinc fumes and compounds. They can be really dangerous, like a strong fan blowing across the forge or a metal fume rated respirator. Think of it like melting lead or playing with Mercury. Mercury on normal unhurt skin wont hurt you for a short time but the fumes that come off will hurt you over time same with zinc.
Fair enough. Lots of failure, yet lots of learning, and better your failures than ours 😉 Thanks!
I just learned that some molten metals are hygroscopic, so it’s very important to preheat your molds to drive off moisture or you could introduce surface defects and porosity. This made me wonder if it wouldn’t be better to seal the crucible since the propane fuel source produces a great deal of water vapor. Alternatively you could build an electric model but a lid still seems like a good idea since even casting on a humid day has been reported to effect quality.
Use flux to help remove impurities and dissolved gas as well as improve flow characteristics during casting.
I used refractory cement for my furnace. It can melt iron.
Thanks for the tip 😃
For the bubbles, look into flux. That can help de-gas the metal
Sweet, thanks 🙏
Flux does not degass aluminum, it just helps seperate the dross. To degass, you need to blow a purge gas through the molten mix
@@alextreseder6274 thank you 😃
I'm thinking if you redesigned the mold so that the heating ports were radially extractable tapered rods, and added more draft angle to all the vertical walls, you could make the mold reusable rather than having to sacrifice it each time. Apart from that, I'm really impressed with this low cost cast founder idea. If reusable versions of the molds were available to buy online, I could see them becoming popular with people who just want a cheap and easy way into occasionally casting their own alloy/brass parts.
Apparently you need to be careful with concreat foundries. Concrete doesn't really like being seriously heated, and I vaguely remember reading that the stresses when heating can cause it to almost explosively fragment.
You might want to look at using "Perlite" (Available from most gardening product suppliers) or "Bentonite" (Sold everywhere as unscented clay based kitty litter) instead of sand in with the plaster. Both these are better thermal insulators than sand, cheap to get, and should make the finished forge get up to temperature quicker (Subsequently meaning less gas is used per melt).
Thanks for your detailed comment 😃 I agree that reusable molds would be of greater value. We will continue to iterate 😜. Cheers, Dave
Hello, I just wanted to give you the knowledge that I know from working in a foundry. Like alot of other comments yes flux the metal and remove impurities. Borax works well and believe it or not so does sawdust. Second thing i can help with is the bubble situation. Don't rapid cool with water let is slow cool and also vibration would help bring the bubbles to the surface. In the foundry they use chlorine gas to help off gas the metal which is a no go for DIY. Also you were wondering what the black is on the copper. It is oxidation, Not much you can do other then grinding it off. Hope this helps.
Nice mold! I've been trying to make a foundry such as yours. Minimal quantity items and great results thanks for this ... Hope my tiny printer (monoprice select) can print smaller sections. Also you may try later a silicone mold. Omg just saw the molten brass goggles .... SAFETY SAFETY.. 😨 GLAD U ARE ALL OKAY
Silicone molds are a good idea but probably expensive. As per the safety, I was wearing a leather welding hood over my head and am glad I did, but yes indeed, safety is very important. Thanks for posting 😃
As a extra tip when using crucible always place a small piece of cardboard under crucible to prevent firebrick Sticking and foundry floor erosion
sift the plaster before use and it might be better to tilt the burner less than 90 degrees to the center cac 20 degrees outside so that the flame partially circulates around the center and does not burn it directly
Nice project, but I have a couple of comments/suggestions.
1- Make your inlets so your flame swirls inside the foundry instead of hitting your crucible at 90.degrees.
2- As is, you are also insulating your crucible from the heat with the internal concentric wall inside so it is taking a lot more energy to melt your metals.
That should simplify your mold construction and also reduce the time and propane you use for melting your metals. (and also maybe extend the life of your crucibles)
That’s a great advice. I agree with your recommendation. Thanks for leaving a comment 😃.
preheating the casting form is a good idea
I really like this idea, I use an induction forge that could make it easier for you to melt this kind of stuff.
We had that thought, but wanted to try to make a super duper easy propane foundry. Thanks for watching and leaving a comment though 😊. I hope you enjoyed the video. Cheers, Dave
I think there are some Open Source Schematics for Induction Furnaces out there too, so given that as well as your ability to make stuff documented by these videos you should be able to do it!
@@ericlotze7724 sweet, we’ll have to give it a try 😃
@@ActionBOX But yea propane is way easier!
@@ActionBOX the video was great, I was thinking of using this method for the insulation for my induction heater, really like the idea of it.
That's brilliant. I just ordered a $500 furnace, but would have started with this if I had seen your video first. I might try printing one anyways to give it a try.
This is the first video I watched on your channel. It just popped up randomly but kinda looked interesting.
Don't regret watching it all, very very interesting and well edited. Props to you my guy! Keep up!
Also, i don't have a 3D printed nor I have any metal melting equipment, and don't plan on doing it, but watching other people do it is super interesting
I mix plaster of Paris with a 3d printed whisp like stirrer that has a long extension handle that is inserted into a standard drill. It works great on the fine lumpy particles of the plaster
When you are casting brass use 1 tsp of borax to bring any impurities to the surface of crucible. Next use a spoon to skim surface of product and repeat until surface tension is calm. For copper and aluminum simply skim surface of chunks and repeat until surface tension is flat and calm.
Several thoughts. After finding that copper and brass fuse to the metal of muffin tins I now use rammed sand molds to pour all of my ingots into.
On my first foundry, I used a weed/roofing torch for my burner. That worked really well. I now make my burners from assorted plumbing flanges and pipes. I have no problems melting copper. I have not tried to melt cast iron yet. As the weed burner hooks up to a 5 gallon propane tank it is much much cheaper that the itty bitty bottles.
Rather than using plaster or cement there is a product called Satanite. I use it for facing the soft fire brick in my foundry. It holds up really well.
Lastly-a huge safety issue. When melting brass the zinc will boil off in weird yellow/green fumes. It is hugely dangerous to breathe. The same goes for anything that has been galvanized-like steel plumbing pipe. Breathe in enough and you get zinc fever and then you die.
Thanks for sharing your experience!
The holes could be due to wet molds and gas trapped inside of it, most metals you can throw borax at it to degas and float the impurities up to be skimmed off (hint). Aluminum is king for trapping gas inside and not releasing hence the micro bubbles
You guys should try recycling the copper into custom electrodes for your EDM.
😮 OMG, that is a great idea hahah. I hadn't even considered that. we'll give it a shot for our next EDM sinker video 😜. Thanks for dropping an awesome comment. Cheers, Dave
@@ActionBOX Sweet! Looking forward to it.
you have to de-gas aluminum before casting. you can buy degas tablets that add after melted.
Having recently discovered the ability to paint sections and supports in different material.
That would make removal of the finished mold super easy. You can use HIPS or similar material that you can either dissolve or snap on surface edge.
It is strong enough to hold while pouring. Then come time to separate. You can either dissolve a section to ease removal or snap the mold apart in sections along those lines you painted into it.
Thanks for sharing 😃
Since you asked, the best way to mix plaster is by hand but you need to do it similar to the way you mixed the Medium Foundry plaster. Start with the water then add the plaster to the water slowly as you mix with your hand. It keeps those lumps from forming in the first place, and if one does manage to form you'll feel it and can deal with it. For refractory like you are using, mix the plaster and sand first, then add that mixture to the water. Cement can retain water for long periods of time and doesn't stand up to heat well as a result. It might break down over repeated uses, but you might get better results by sifting out the large rocks first.
Also, to save your cast-iron molds, make sure to heat them up before adding your molten metal. Then you can extract it easier, like you did with your graphite mold. No idea about the voids, though. My experience is with small melts for jewelry making and not for large ones.
The idea is ingenius, and the execution was brilliant! I am definately making one of these!
After watching a video of a guy splashing aluminum right onto his foot (he was wearing some regular shoes) I was kinda nervous if something would eventually happen to you for not preheating the molds. Glad it turned out to be only a close call.
Great video!
A de gassing flux will sort the bubbles out, Borax is good and readily available as is Sodium Bicarbonate (baking soda). Both are cheap and readily easily obtainable. A couple of teaspoons wrapped in baking foil and pushed to the bottom of the melt 5 minutes before poyring will give much cleaner results. Allways pre heat the ingot molds prior to pouring...
Foundry work is so much fun!! I was really lucky to go to a high school that still had metal shop and wood shop so i got to do many different projects
You want something closer to a whisk, lots of thin bits that'll stir up the mix and break up clumps. Egg beater would be good too
i can't tell you guys how grateful i am for this video. this video literally encompasses the spirit of experimentation and improvement all into 1 video, pure science. got a lil bit high off of it too lol
Haha thank you! We love to show both our successes and failures on the channel. We’ve got a ton more cool videos coming - stay tuned!
To mix the plaster properly, you first have to add the water to the container, then add the plaster powder spreading it evenly among the container. Finally mix it. This will give you a thinner liquid and a longer pot life.
1-1/2 angle iron works well for molds. I use it for copper and aluminum bronze ingots all the time. It’s walls seem to have the right relief angle for the sides and is really easy to cut and weld to size
Always pre-heat your molds!!!!
Sweet, thanks for your input 😃
I really love the way you describe your trials
Thank you 😊
I've noticed on other casting channels that they are very particular about separating the brass and copper and aluminium from items like steel screws, plastic handles and so on. Plastics can introduce gasses and it is always worth it to remove dros and to degas.
Thank you for sharing 😃
You want to use a flux to help the metal flow. This will also help lighter impurities (called dross) rise to the top to be scraped off before you pour. You can use borax as a flux.
Super glue accelerant is super useful if you’re ever glueing a print that tricky to clamp
Super glue accelerant= baking soda. Learned that trick from Adam Savage.
Another great video, loving the content your putting out 👍🏻
Very interesting. I like the possibilities that this could be used for DIY projects. Thank you.
Thanks James 😊 I’m glad you found our video useful.
For the aluminium dots. Try Heat-treating the aluminium to T5 grade alumunium. It's really simple. Just put it in the oven on 180 Celcius for 6 hours.
Good work guys. Some flux would help with the quality and purity of the final products!