How NOT To Cast A Historic Bronze Cannon Barrel. FarmCraft101 

"my two foot cannon is one foot long..." I've heard that before..

Make a traditional cope and drag mold with the green sand. Pack sand real good and add sprues to vent properly. Paint inside generously with an alcohol based ceramic paint for a very smooth finish. I worked in a foundry as a mold maker and that was our process for the cannons we poured. Cheers!

2 and a half minutes in... "I always see them use X but I don't have X so I'm just going to use Y." ...famous last words.

Tensile strength does NOT equate to allowable chamber pressure. You must use the thick walled cylinder equation to compute the radial stress.

It looked just visually that there was no way that crucible held the same volume as the foam cannon blank.

It's not a failure it's a valuable lesson so well done and keep it up I know you will succeed

A fantastic video. Way more interesting than watching a solved problem.

I bet those fissures were from the foam boiling/gassing out. There was no vent for the gasses to escape.

The water is brought to boiling point faster than the expanding liquids/ gasses can escape in the way it normally would, so it surges to the surface so fast it 'pulls' non-boiling water along with it when it breaches the surface.

Your mysterious explosion was probably a steam explosion. Killed a lot of steam engineers back in the 19th century... also, large crystal structure is weaker than fine. As to green sand, I'm pretty sure you need to add a little diatomaceous earth to the mix.

I recall reading a very long time ago that they learned to cast cannon muzzle up so that the porosity would be in the bell and not the breech. They also cast the cannon blank a foot or more over-long, and the sawed off the top (front) foot, since that brass would be too porous to use. I was not particularly interested in casting when I read that, so I don't recall any more details. Possibly they did not know how to degas the brass at that time. It would have been interesting to take test samples from the bottom and top of your pour to see how much porosity you had on one end vs the other.

After reading some of the comments and replies thereto I feel that a little "Metallurgy 101" is in order. Phosphor copper does NOT remove hydrogen from copper base alloys, it is in fact a deoxidant and is thus used to remove the ever present (In badly melted copper) copper oxide. In this case the zinc added via the brass would likely have already done that so the phosphor copper addition was unnecessary. Left over phosphorous (and that is what you would have had) forms a low melting point eutectic with copper that is about as fluid as methylated spirits - it will rapidly penetrate coarse or loosely rammed sand moulds forming an ugly composite of sand and metal - (well, fancy that - sound familiar?) that is, as you found out most destructive of tooling. The voids seen in most if not all home melted copper are NOT hydrogen. Even when done well lost foam is not a technique known to produce the best quality castings. The idea is that the gases from the styrene escape through the sands and NOT through the liquid metal. Styrene has the general formula (C3H8)n. {EDIT, this is a mistake C3H8 is propane what I meant to type was (C8H8)n and in response to a request from a commenter I have edited this post to both correct and expose my typo. END EDIT} At the temperatures involved here some decomposition of the styrene is likely thus the gas bubbling through you metal did contain hydrogen, and some pick up seems possible perhaps even likely. In any case to assume that bubbles (save perhaps inert gasses) traveling through metal do not leave damage in their wake is foolish in the extreme. "Linear Grain" - Hmm, that's a good one - Its actually called "columnar grain". It results from grains (dendrites) growing inward (into the remaining liquid metal) from the outside being constricted into growing in just the one direction (inward) by the grains growing alongside them. Just a quick eye ball of that crucible and pattern told me that there was little chance of there being enough metal in that crucible to fill that mould. The number on the outside of a (good) crucible is its capacity in Kg of molten copper brim full - you can always use that minus a bit in any calculations to see if enough metal is available. I think that you were lucky that you did run out of metal as had you not I suspect the mould would have floated up (from the lowest box junction) and you would have got very wet and hot boots, moon suit or no. I would suggest that clamping or weighting the mould a much better safety precaution than one of those awkward and restrictive moon suits. The gauge length on you tensile specimen was a bit short - actually a lot short. This is not all that I saw but its all I have time for now. Fred

Not gonna lie...your 7:00 "explosion" actually scared the shit out of me lmao EDIT: Also you don't need to use the little 4.5' grinder to grind this...that would take forever and like you said..use 50 wheels. Get yourself a corded 9in grinder and it would have taken care of this in about 5-10 minutes with only 1 wheel.

11:40 the water jet guys will cut it for you PERFECTLY.

More book learning: I don't know about bronze, but with steel you polish the surface then etch it to see the grain structure. The grains may be microscopic. 100X magnification might be needed. Etching bronze might require nitric acid.

Pour it horizontally. Use the foam as a form for the green sand but remove it before pouring. You have plenty of experience doing it this way.

And thus, the fuckupium alloy was discovered.

You have nowhere for the foam burnt gas to go, it has to come up through the same hole your pouring into, so the weight of the metal is allowing pressure of the burning foam to build and deforming the mold. Yes sand does allow some venting but packed sand on a large pour does not have enough to vent all the foam gas, Also you have the largest amount of metal on the bottom with the most heat trying to boil the foam gas and pouring bubbles through the area that cools the quickest because it is the thinnest. IMHO this is why the bottom stretched. I would add vent sprues 1/2 inch diameter and about every 4 inches to allow the gas to escape as you pour. and factor 25-30% extra metal for the pour. Also I would allow a slow natural cool of the casting like 24 hours. Hope that helps some keep up the good work!

Water expands about 1700 times when it flashes to steam

8:58 the reason it exploded is because of a localized steam explosion. As the surface cooled, it contracted which caused some molten metal to squirt out. That molten metal hit water and locally superheated it beyond vapor temps. That caused a local steam explosion that propagated thru the surrounding liquid.

Just seeing the size of the crucible, I was wonder how it would have filled the cannon size you made with the foam mold in the first place. It didn't look like enough physical volume for the foam cannon you turned on the lathe. And that answer was, it won't. I have to agree with making a green sand setup and pour it in a horizontal fashion rather then a vertical setup. That way the weight of the brass itself isn't forcing the sand out of position. Also you could use some vent tubes to assist in that pour to equalize the flow. You could even make a sodium silicate sand core to insert in the center to help with the hole once it is poured. And allow the pour to cool off for 24 hours. That way it helps control the brass to cool on it own and not crystallize from a quick shock cool down. JMHO

For safety rather than lighting the fuse and run, get a firework igniter. MJG has consumer ematch now that doesn’t require an explosives license. You can run two wires to a battery and be far away when it fires.

You remind me of AvE. I like how you explained the math and were very open about how you were TRYING this out. You are figuring it out as you go. That's awesome.

You can cool the cannon from the inside out using a special mold when you cast, this will increase the compressive strength of the barrel. Besides that, reinforcement bands were used often enough for even more strength around the breech.

The linear grain is probably due to the direction of solidification. The metal will begin to solidify along the edge and the crystals will grow toward the center as it cools. Your grain pattern will be in an axial pattern. You can also do a macro etch to see the overall grain size and pattern. A common macro enchant has hcl (commonly called muriatic acid) and ferric chloride. Use caution and good ventilation before mixing and using

3/4 inch bore won't work. 3/4 inch is 19.05mm and cannons are 20mm and over. ;)

I worked as a pattern maker years ago...interesting video, but you are going to get hurt. Not allowing for venting and shrinkage. You need runners and risers to allow for shrinkage as it cools. By eye, I could see you were lacking in material. Large castings are a whole different world than trinkets.

If you ever worked in a foundry, you learned to fear the steam explosion.

I believe your force calculation is wrong. You do not need to divide by two. The force on one side is the same as the force on the other and its the same at the test cross section (newtons third law). This means you are almost at your target your target! Great video, thank you very much

The vertical position creates too much pressure on the sand. Can you use plaster of Paris? Can you design a horizontal rig with pouring flues along the barrel? Interesting project.

You don't have half of the force pulling each direction, you have the full force (5,188 lbs) of tension pulling the sample apart, or 40,850 psi. ----------------------------------------------------------------------------------------------------------------- UPDATE (4/01/2019): After watching his video titled "Building a DIY Tensile Testing Machine. FarmCraft101" (ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-RxoLwyjSRaQ.html), I see that I misunderstood what he meant by "both sides". [Thank you @Kevin Martin] He is referring to both sides of what is essentially a lever on his test apparatus with the hydraulic jack applying force at the midpoint while one end is applying tension to the sample and the other end is fixed. So DIVIDING BY TWO IS CORRECT!

*If you add coal dust to the sand that contacts the metal you will have a much smoother finish. They sell the sand commercially or you can grind up coal and add it. There are some good youtube videos on how much better the rests are but can't think of the name at the moment* After seeing your finish it looked exactly what the coal dust fixes.

I'm not into metal working or anything, but this was fascinating!

Hey! I know I'm a bit late to the game, but that water explosion on your first quenching was just a bunch of superheated steam forming one big bubble around the cannon. The Leidenfrost effect took over, meaning that the hot metal was covered in a temporary sheath of insulating steam which kept it out of direct contact with the bulk water. Once that vapor film broke you got the distinctive "pop" of a bunch of water boiling instantly on contact and a huge steam bubble.

Accurate composition of the alloy is of the utmost importance, 88% Cu, 10%Sn, 2% Zn = Gunmetal.

Casting in sand requires the sand to be pretty tightly compacted all around-not just immediately adjacent to the shape. Especially with such a tall casting you want to make damn sure that the sand won’t budge when the foam vaporizes. I’m not sure that sand would even be the best choice, maybe use a fine clay or plaster shell around the foam with packed sand to support the shell. The explosion in the water was from the hot metal vaporizing the water similar to why you don’t add water to hot oil. Also, in 1500 the cannons were beyond sketchy...exploding cannons was pretty par for the course and often was more common than not. There were some interesting stories about how they were tested before field use.

Dont quench it, let it cool slowly. Will give you a stronger metal.

Some of the water very close to the hot metal is heated up quickly at alteres shape from liquid to gas form. (Steam) As steam´s volume is factor 1000 to water, - it expands and pushes away the water around it which makes it splash all over like an explosion.

18:20 Yeah I'd have to disagree with you there bud In the old times they used to use two dies to draw it out one went in the eye of the anvil and the other one was attached to a hammer and another guy hits the die on a stick and the first guy moves it along the metal to Change the grain structure along the entire cannon barrel depending how big it is depends on how long it'll take to draw the grain

I can’t wait to see the cannon. I have a small signal cannon that is deafening but not the satisfying kind of boom a larger cannon like yours will produce.

The sand didn't look like it would keep its shape once the foam was gone. The sand I've seen used in pouring metal was much finer grain and very compactable.

Stunning experiment......it’s been incredible watching your journey and learning every step of the way. I think the sleeve is the way to go....looking forward to the next instalment.

I cast my first brass part 2 days ago and the guy who guided me told me that, unlike steels, slow cooling makes brass really hard while quenching as soon as you can makes it much more malleable and soft. My guy has been a machinist for almost 50 years. But check it out for yourself. And, yes, my casting looked a lot like yours, sand coating wise.

Man! The fake explosion at the pour scared the heck out of me in my headphones! lol

I've found that coating my foam in sheetrock mud before casting helps keep the metal smooth and contained

The pressure of the molten bronze is down in the form nearly 10 bar!!! From this the sand makes problems. Glue the sand together. Or horizontally.

Fascinating stuff. Maybe cast horizontally with a multiple manifold entry pour and many gas escape ports?

Finally RU-vid recommends something genuinely awesome and that actually interests me.

This guy has the right attitude. Things went wrong, but he accepted it, even made it public for the rest of us to learn something. He made sure to learn all that he could from what happened. He will succeed.

I seem to remember adding molasses to the sand and later Co2-ing the mould before casting and you have no vent/filling sprues

Hey man, you don’t need to divide your tension by 2. (I’m a current engineering student, I could be wrong) the tension held is equivalent on both sides, so the central part that broke had opposing forces of half the tension pulling on it, meaning it withstood the total 40k psi, not 20.

my answer: cut it with a waterjet :)

My heart sank when I heard the boom. (Browser was minimised)

Great video, thank you. Nice job machining the tensile samples. I think, however, that your mechanical calculations are off, if I followed them correctly. (1) The axial stress in your tensile sample is the force exerted by the cylinder divided by the area of the sample, as I think you rightly understood. But if I followed you correctly, the division by 2 is a mistake; the full force delivered by the cylinder is available at both ends of the sample and is, in fact the tensile force throughout the sample. So I think you are off by a factor of 2 there. (2) If I followed correctly, you are later in the video comparing the tensile strength of the material to the pressure expected inside the cannon barrel and expecting to be OK if your tensile strength exceeds this value. This is not correct; the hoop stress in the cannon wall is approximately equal to PD/2t, where P is the pressure, D is the bore, and t is the wall thickness of the barrel. You want the tensile strength to (far) exceed the *hoop stress*, not the *pressure in the chamber*. If you compare to the pressure, you are off by a factor of D/2t, in the dangerous direction. You were correct in stating that you need sufficient wall thickness. Perhaps I misunderstood your reasoning, and you have everything right in your mind after all, but I was thinking of the consequence of basing your dimensions on a calculation that is off in the non-conservative direction, and thought I would chime in for safety's sake. Looking forward to seeing more videos in this series!

Fascinating, and a tough project to solve. I hope you could catch all the bronze chips and dust for reuse! Tungsten carbide inserts on the lathe could have helped but they are brittle and expensive, so the sand could still have won.

I already know the problems. The foam will melt and cause gas to well... you already know expanding gases and castings don't work well.

A wet diamond blade (as used for masonry, ceramics and metals) will cut that agglomeration of bronze and sand.

Try D x D x .7854 (same as pi r squared but easier,,, trust me it is the same.) that gives you an area of .127 next equation is 1/ .127 which gives you the amount you must multiply 1200 by to end up with PSI which is how tensile strength is measured.( unless your metric) pounds per square inch. It might be confusing but it works. Same equations for metric just different units.

K12 firefighter saw with a diamond edge blade will cut through just about anything.

One thing I noticed between you and other lost foam cast videos is that you did not coat your foam model in plaster.

I actually made the same thing. I casted it out of copper and used lost wood casting. This kinda is my own invention, however this works perfectly. Video will be out at some point. 😅👍🏼

The explosion. Water turned to steam. Steam is 90 x more volume than water. You get a very rapid expansion of liquid water to steam with a pop.

Tip from a former pyro: instead of hand-lighting a fuse and hiding, use an electrical ignition. You can run THHN from something as small as a 9-volt battery and then run it through a hairpin of thin wire, which will heat up enough to ignite primer. Sub out common model rocket igniters for the wire & primer and away you go - way, way over behind your rampart where you can watch it blow on camera when you connect the circuit instead of waiting on a fuse and wondering if it's going to go off or not. Source: I had a lot of little pits burned into the backs of my hands from using professional fuses (which are made with bits of explosive in them so they won't go out, even under water - some of which fly off and burn into whatever's nearby), and after even a few of those didn't seem to go off when connected to 3-4" mortars, we switched to electric only so we'd not only stop getting burned but get to keep all our extremities if something went wrong. That, and bury the dang thing up to the tip in a bunker of wet sand.

they had experience... canon crafters were at first, bells crafters

Dry sand next time. When going into the unknown it would be prudent to wear total welder coveralls. Investment up front pays off big later with no medical bills added to the project.

be careful!.. engineer that cannon to approx 3 times the pressure is needs just to be sure you don't blow your face off. great vid brother..

it exploded in the water like that because the water filled into a fissure then quickly turned into steam or even super heated steam, much like how old faithful spits out water in jellystone

You can't fill a one-pint pot with only a half pint jug. And you can't fill a 20-liter canon cavity with a crucible that only contains 10 liters of molten bronze. And you can't make a quality cast without using the right casting-sand for the metal that one wishes to cast and the casting-sand has to in compressed to the right Shore measurement. Which is about 25% by volume. en.wikipedia.org/wiki/Shore_durometer You may have intercrystalline grain growth due to a too high casting temperature, thus less tensile strength. Run a test: cast small test blanks and try to keep the temperature 10% over the metals melting point and don't shock cool. Run your tensile strength test and see what the difference is. Check the interval for bronze: the interval for metal is the temperature at which it solidifies. Some metals have a short interval other a long interval. Some go from liquid to solid with just a 2-degree temperature drop.

Can't help but wonder if all that foam played a roll in the molecular structure of the metal. I'm sure it would be minut but nonetheless it could change a little.

The grain structure probably won't be obvious from the fracture surface alone. If you can grind and polish a piece to a mirror finish it can be etched easily to reveal the grain structure. Someone suggested a ferric chloride etch, 5 grams of ferric chloride in 96 ml ethanol and 2 ml HCl may do the trick. Alternatively a nital (e.g. 2% nitric acid in methanol) may work. Good luck!

Video randomly appeared within suggestions. Can't. Be. More. Happy. To. Have. Made. That. Clic. Tyvm, instasubbed :)

When you get around to test firing one, I would use a model rocket igniter. Much safer and more reliable, unless you use professional fuse.

I'm not a professional but isn't it supposed to be poured all in one go ?

It "expoldes" because the water vaporizes underneath the hot metal. the metal itself is so hot that it can turn water into steam. thats why it "explodes inside" the water.

Your calculation was flawed. You should not have divided that load by 2. Your material is twice as strong as you calculated. Cool video

Great video! Nice display of skill and ingenuity. I learned a lot. Loved the subtitles and use of slow mo/fast fwd video. The CGI BOOM was hilarious.! 😂 Keep it up. Thx from Vancouver.

There are diamond circular saw blades for cutting block.

The explosion was a steam explosion. Steam is thousands of times larger in volume than liquid water, and can expand at rate similar to a detonation/exposion (depending on temperature of the source). Steam explosions can be very dangerous. If you wish to avoid steam explosions, like what you experienced, switch to a different liquid than water with a boiling temperature above 212 F. Ideally, find a liquid above the temperature of the metal, i.e. metal temperature 400 F, use a liquid with a boiling temperature above 400 F. I hope that helps.

John could you make the barrel on your lathe, using heavy walled pipe.

i'm an american. i use 1tone of material to get a bullshit sand crap and be proud of , on youtube

As others have observed, as I watched you and you said "I wonder what sort of problems I will have..." I knew right away because I saw your foam - no sprues. There is a channel called Black Beard Projects. He casts large pieces of aluminum, and those videos illustrate the idea of a sprue and how it works. There is one where he makes an axe which will be particularly instructive. Good luck! I will eagerly await the next attempt!

Foam doesn’t fully burn off, ALL green sand is very essential. Hard pack is essential. ...understanding the physics of what you’re doing...best idea

, nice, good way to show whole process of failure and how easy it is for us with all tech we can use... :-)

Me at the mock explosion: Damn you!

It looks like you're working on a concrete slab. Don't do that! A molten metal spill will result in a steam explosion (like the one in yer bucket) from the moisture in the concrete...... Ask me how I know this.... Correct foundry practice is to do the melt & pour on a sand floor.

You need a diamond cut off disc and a angle grinder

The old time black powder was less strong,We had some old rock salt size when I was a kid,less pressure for civil war cannons!!!! Thanks for the videos

I was staring so intensely at my phone the mock explosion kinda got me

12:15 ... just a point of safety... you should NEVER touch a blade while the motor is live... NEVER!!.. tut tut

When you put the hot casting in water, it first hissed a lot, then it exploded. You asked if the physics for this is known. What you saw is something called the Leidenfrost effect. What is happening, is that radiant heat (ie: intense infrared light) from the casting is vaporizing a thin layer of water. During this effect, the steam is physically separating the water from making contact with the casting. In science textbooks, the traditional demo of this, is water drops on a searing hot skillet, that zoom and bounce around. Those droplets are riding on a cushion of steam. Because there is no contact, the droplets move with little friction and zoom or bounce around the skillet. But of course your casting is cooling down. So at some point, the radiant heat is too low to generate the layer of steam. This layer of steam is relatively insulating, compared to a layer of water. So when the steam layer disappears, the water makes direct contact with the casting, and the water can then get heat from conduction. So it heats up violently which is a steam explosion. So the hissing is the Leidenfrost effect generating an layer of steam by radiant heat. And the explosion happens when the liquid water makes contact with the surface, and generates steam by conduction. en.wikipedia.org/wiki/Leidenfrost_effect

"I'm actually larger than that pattern by almost an inch"

that wood blade is impressive!

Great video! Long story short....... many years ago (33 years) a family member was going to shoot a cannon off into a lake. I was quite young, not knowing how dangerous things like this are I was standing slightly back but between the boat house and the cannon. Just prior to firing, another family member called to me to get away from this cannon....... guess what happened..... The part that blew out the side where I was standing and made a clean hole approx 5" through the wall of the boat house!!! I was very lucky!!!!! I am glad to see proper testing and safety precautions being taken seriously!!!

I`m not a mathematician or anything like but when you did the tensile calculation you divided by two because the press was pulling from both sides (16.50) , i do know presses and they only pull or push from one side and the other is fixed , just saying in case your strength is better than you thought.

subscribed, like to see people that upload the unsuccessful videos, a lot of info to take away from them. cheers mate

The problem is the math. Pi are NOT square, Pie are round. Cornbread are square.

make a core for the mould so you don't need so much metal in the pour ! must have been a heavy lift back there

There were also canons that were constructed of individual iron rings.

so, let me see if I understand this right ! 21 minutes, no cannon at the end but some BULLPOOP MATH *NO ONE CARES ABOUT* and maybe, MAYBE a second video that is not here (at the end, the link is directly AFTER you smelted the cannon) nice video, what's next ? 5 hours of manually chopping toothpicks ?!? :D

What of work has led you to these kind of hobbies?