That turned out wonderfully, not counting the bubble of course... Yes, you were correct. I did not use a core. I was just using an old ball pien hammer as a form. I filled the bottom box, Drag, I think it is called then trenched out a spot to fit the hammerhead and hammered into the drag until it was half below the top of the sand, then took it out and sifted some petorbond into the mold, then put the hammer back in and hammered it back to the half waypoint. The eye of the hammer is vertical during this... Anyhow, then I filled the eye and packed it down as hard as I could till it was level with the mold on the outside... Well, surprise, surprise... the core always comes out with the hammerhead... After a bunch of tries, I said to heck with it and poured it full of wax. The was hammer turned out great. So, I widdled out the eye and molded it in petro bond, put it in the oven, and melted the wax... Lol... The darn core caved in when the wax melted... Today, I took my wife out for a ride in the woods on the ATV to enjoy the Autumn leaves, then I just watched a bunch of videos confirming that I was out to lunch on the whole idea... I think I will turn a whatever the thing is called that you use to tamp the sand down, on my lathe and make a brass one of those as a first project... A hammer seems to be a big ask for a first casting... KISS as we used to say in the Army, Keep It Simple Stupid... I appreciate your videos so much. I intend to watch them all from the start eventually. Thank you and be well...
Be careful, some of my early videos are full of really bad technique. I wouldn't want you headed down that path. Most hammers, that I've run across, have a tapered eye in them. I think the top is the widest. That way when you drive a wedge in it will spread to a "V" shape and keep the head from flying off.
3d printing the patterns is a great idea, but next time, design some registration pins into the 3d print. As someone else pointed out, get a smooth, easily sandable finish by spraying the pattern with a self leveling epoxy primer. Great video...
Thanks, couldn't agree more. Now that I've got my own 3D printer I can start controlling stuff like that a lot easier. I had to depend on a friend for this one and he forgot. I'll have to get some primer. Sanding this stiff is a pain in the butt. ;-)
I don't think so. Shrinkage draws from the hottest, largest pool. Bubbles can spontaneously form as shrinkage creates lower pressure in the hottest, still-molten section. Shrinkage draws from this hottest, still-molten section. If the sprue and part are similar size and close together, no telling where this will happen. if the poor-in is much larger, and the part is far enough away to allow the part to cool before the poor point, then the hottest section that shrinkage is drawn from will remain in the sprue. If the gate is too small, it can choke off too soon and block the part from being fed by the reservoir. Any air bubbles that spontaneously form in the sprue will not matter, because the sprue is waste anyway. After trying with larger sprues, farther away from the part, with decent gates, cut a few sprues open. you will find large bubbles in the center not uncommon.
You know, I do smile every time I look at it. I'm looking it right now, well actually I'm looking at the keyboard because I cant type but its right here next to me and I look at it all the time. ;-) Thanks!
I just look Paul's video and I must agree, your hammer looks much better with the polished finish. To avoid these air bubbles inside your piece, add on both sides two to four additional small channels where the air could also escape. This pieces could be cut off later easy. If you clean up the hole, try to fill it with tiny bit of molten aluminum bronze. Greetings from Germany.
I thought about filling it with a small bit of melted bronze but I think I will make an ever bigger mess if things if I do. Maybe I will try that some day. Thank you.
I had similar problems at start. Thin vents act as small pumps, pumping away metal when it solidifies and shrinks. You need to design reservoirs (risers) of molten metal into mold. They need to be thicker than the cast part so they can feed molten metal in while it solidifies thinner parts first, filling voids. For small part casting its easiest just to make nice fat gate +thicker sprue that will do the trick.
I did already. We all do same mistakes at first :) and then learn. When casting bronze its better to have longer runners also because as you found out there are always oxides/slag (black grainy stuff at your hardened sprue bottom) in in melt. With long runner slag gets stuck in it and does not get into part. Always make nice fat (wider than the part) riser at the end of runner to have a perfect cast.
My daughter accuses me of being a 13 year old girl. I guess she's right, clearly I prefer shiny over functional ;-) I've gotten a ton of great comments on this one that I can't wait to try out just to see if I can improve things.
I came from Paul's channel. This was a great video the only thing I think it needed was some macro shots of the hammer rolled in while you were talking about it. I'm definitely subscribing and look forward to the content you'll produce in the future.
You know I had someone else say that about the macro shots yesterday as well. First time anyone has ever mentioned it and I hear it twice within a few hours. ;-) This week's video has some more close shots. Thanks or the sub and welcome!
Excellent! Really dig the fact that both you and Paul used 3D prints for both the pattern and the core. I think you got plenty of advice on how to prevent voids so the next hammer will be even better. Great job!
First, that's a damn fine looking hammer - I absolutely LOVE that polished finish. Now for some tips to help in the future. 1st - you likely needed both more 'head pressure' and more material available to combat shrinkage. Having a taller cope (one of the reasons to use 2x6's to make them) aids in this - the higher up from the part, the more pressure the metal puts into the mold. 2nd - you really should make a conical sprue (and risers, depending on the casting's shape). These act like reservoirs to feed in material as the metal in the casting cools and shrinks. They also serve to increase head pressure - metal is heavy. You seemed like you had a healthy enough gate (needs a bit of cross section to allow the molten metal to flow without cooling and blocking it), so you have that going for you. All in all, that was a great result for that flask - you really should use a taller cope, if nothing more. A taller drag just makes it more stable for handling. One thing you can do to help is to get some conical forms to use for sprue's/risers. Not a lot of taper - maybe double the bottom width at the top (inch ish at the bottom, 2 -3 at the top), but you just place them in with the pattern when filling and packing the cope. Then all you have to do is remove them and cut some gates. Skewers work well for vent holes in piece, if those are needed. Gah, I can't wait until I can do this myself...I rather badly want access to a forge and furnace again... **edited for spelling**
Thank you! I got another comment about using small vents, like punched with welding wire. I''ve been treating the vents as risers and not really thinking about their purpose of venting gas. I'll definitely look into better venting going forward. I've also gotten the comment about conical sprues and risers that I will do as well.
Another problem could be dissolved hydrogen forming bubbles as it solidifies, if the above solution does not completely eliminate holes. In the aluminum foundry I worked in, we used extremely dry nitrogen gas bubbled through the melt, though a solid flux can be used to achieve a similar effect with way less cost.
I cant see me getting to the point of bubbling dry nitrogen through any of my melts. ;-) But I do appreciate the info. Always good to learn more. Thanks
+swdweeb - You're welcome. One other thing I'll throw at you is a great way to use the flask you have - you can make tall external risers out of decent sized food cans. Check out Brian Oltrogge here on youtube - ru-vid.com/show-UCOywIdppbhn6hkgcEtDMatg - he does exactly this in a very simple, elegant way. It's a great way to use thinner flasks (and consequently less sand) and still get fantastic head pressure and fill volume. His style of using wells and curving gates is also excellent for reducing turbulence in the pour, reducing air entrapment in the first place (I don't think you has issues with this, though). Carry on. :) (I admit - I went on a casting binge watch after your video)
Not the normal type of video I'd watch, however was messing around with a RU-vid geo locator, and this came up as having a geo tag near me. Glad I discovered you, and best of luck in future castings!
Alignment pins are put in the holes in the pattern , riser blocks a are used in the gating system to stay hot longer and feed the part while cooling to control shrinkage . I ' d try it again on video to show the difference .
to align the parts I suggest drilling through one and partially through the other, while they are together. Drive an alignment pin into the the fully drilled part that extends partially into the other. over drill the partially drilled part to be a slip fit. use two pins, one at each end. you will have a permanent set of alignment pins./
Well done. Those holes are interesting. When I first saw it I thought it was a result of that edge that collapsed. But, it looks too round to be caused by a lump of sand. I will have to dig back to my injection molding classes to see if I can figure out anything.
I could if I still had it. It's been five years since I cast that hammer. I recast it with better feeders so I ended up with a hammer with no voids in it ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MsW4G-J2LA4.html
Look up Chvorinov's rule. Cooling rate is all about surface area to volume ratio. To ensure your casting does not suffer from shrinkage defects you have to make sure your riser has a lower surface area to volume ratio than any part of your casting. Doing this should reduce effects of shrinkage.
I would think that the "void" is a "Vacuum" bubble, where the cooling metal shrunk, and the sprue was already too cold, and had chilled off/shut, before there was any chance for any "liquid metal" to flow from the sprue, into the body of the casting. Perhaps, make your sprues much larger, so as to keep them hot enough to act as a "supply reservoir" until the body of the hammerhead has cooled and hardened throughout. I think that that is what the main function of the Main sprue IS.
I've taken to using larger risers to supply the parts with melted metal until the part cools. So far this has helped the void problem. Have you wanted the "hammer revisited" video I did the following week?
.....No, I have not had time to watch many of your great videos, yet. I just stumbled onto them, this evening! You ARE Living the Dream!!! GREAT Projects, and videos!!! You are Inspiring me, very much!!! (Currently, I'm trying to heal from shoulder surgery, so, it may be several months before I can attempt to do much in my shop, but, It's GREAT to watch your demos! Thanks!!!
You could TIG that bubble using the castoffs as filler rod. I have put soft facing on hammers with al bronze using TIG. Looking forward to seeing more casting... Good Video... BTW: I can't wait until you get some dedicated heat in that shop, I feel your pain....
You know, I asked a tig welder guy that I know and he just looked at me like I was crazy when I brought it up. I had another guys after a very similar comment when the video first came out. Have you seen this video yet? Maybe when you get your shop set up I'll come up and you can show me how its done ;-)
Yeah, I've got pins in a project I'm doing in an upcoming video. A friend of mine printed the hammer head. We talked about alignment pins and then they never made it in to the part. It turned out ok but my stuff will all have pins in the parts.
I wonder if I can fill it with one of my failed rivets. :-D I think we're going to recast this one. Hopefully all of the great suggestions will prove beneficial in another attempt.
Just tig weld the hole up with silicon bronze tig rod or alum tig rod the silicon bronze would be my choice because it’s really hard and would grind off &polish up nice I welded for over 30 years . Kenneth
Another casting project that needed a riser and more metal for the riser. Risers are super important to reduce, possibly prevent, solidification shrinkage in your cast part. Takes a bit of math to ensure the riser is the last thing to solidify in in the cast +25% part solidification time (calculations engineers use with the Chvorinov's rule en.wikipedia.org/wiki/Chvorinov%27s_rule ) The voids are from the metal solidifying at the mold wall, but not enough liquid metal available to fill the inside of the part. The risers supply the additional metal to ensure the inside of the part is filled.
Yeah, another newb not knowing what he's doing :-D I read Chvorinov's as you suggested. I can handle arithmetic but mathematics like this are far beyond my capability. Basically, I need a bigger sprue and riser for doing something with this much mass and surface area. Thanks!
You have to be careful that you don't make the down sprue too large or you will risk air getting mixed with the metal as you pour (there is a way to determine it, but it gets complicated with the mas flow rates) Chvorinov's rule looks more complicated than it really is. The math here really is just calculator button smashing. There are two tricky parts to the math here. First is determining the surface area and volume of the part (might get away with estimating it's a cylinder the diameter of the largest face and length of the hammer), second is solving for the riser size after calculating the solidification time for the part. I failed my way through k-12 math education. It's taken some help and Khan Acadamy, but I can now do very basic partial differential equations (it only seems hard because it can take 20 minutes just doing all of the steps to solve one problem. but the steps are all simple and straightforward). Chvorinov's rule is relatively easy for me now (but I still don't consider myself a math person). khanacademy.org I could estimate the riser size for you if you provide the hammer size details. (or if you can get the volume and surface area from your 3D model, I can get you a slightly better estimate). (I would just doing the calculations, not actually doing any "engineering" to claim validity of the estimates)
Reject the worst bits to a seperate bin.? Initially only throw a minimal amount of the better/new stuff on your shape as the initial layer. Bulk out with the bad stuff. I've seen people get good results with very blackish bulk material. Might need to add some oil.
I don't know how hard it is, I do know that I cant cut it with a hacksaw as the blade just skates across it. If you're looking for a softer hammer, you could just cast copper, but it work hardens so it wouldn't be soft forever
Thanks for the reply. I am very interested in the material for lathing with a mini lathe where harder than alu material might occasionally be needed. The lathe is intended for non-ferrous metals only. I have some test rods of alu bronze, so I could report later how the tools might bite it.
21:20 your entry hole is small and its not on the top of the hammer so when you poured the molten metal the metal got cool fast and left a hole on your hammer or some mud fell from you casting and mixed up on your molten metal so it left a hollow area.
Um... no. Everything you just said is incorrect. The sprue is sized just fine. I use it in all of my castings. You never pour directly into the part. That is a recipe for sand coming loose where the pouring metal hits it. It is also a guarantee of turbulence in the pour resulting in porosity. And it most certainly wasn't because the metal was too cold. The part filled just fine. It didn't freeze as it was pouring. The hole is the result of metal shrinking as it cools. I know you won't watch this but here is the solution to the shrinkage. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MsW4G-J2LA4.html
Using an angle grinder to shape wood! That's my kind of engineering. Very much enjoying your videos. I just had a bad casting day. Perhaps you could take a look and let me know your thoughts on what went wrong? (I just made a video of it)
Heat the face to glowing, then pour some molten bronze into the hole and keep whacking the anvil til it cools. Then heat and repeat. Could be expansion bubble be it gas or liquid. Or 're do the whole thing.
I actually just recast it and got a complete pour ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MsW4G-J2LA4.html the second.. or maybe it was the third time around ;-)
You could try a reservoir under our spruce, and let the mould feed from the top of the reservoir and then up the vents? I’ve seen quite a few people create a reservoir and I think they explain to to prevent shrinkage in your mould ... not sure though
How does that work? With the reservoir below the part (or below the gate) how does the metal flow into the part as it is shrinking? I'm not arguing with you, I'm just having trouble picturing the design of the reservoir and gating system.
swdweeb the reservoir feeds the mould as the metal shrinks in the mould, so the mould should be midway the reservoir. So from gate into a reservoir void then off to the side into the mould and up the vents
This is not an issue of porosity but metal shrinkage as it cools. A larger sprue and deeper well are exactly the wrong thing to do. A large open sprue will aspirate far more air into the casting than the small amount of hydrogen than might get introduced during the melt. A deep well at the bottom of the sprue only serves to exasperate the problem of air entering the part as it simply serves as a mixing bowl full of turbulent air and metal.
it looks like you have quite a bit of turbulence in your mold, which will pull air in as it's being poured. If you used a tapered sprue and choked the sprue, it shouldnt do that. I usually have a sprue and a riser to allow all of the gasses to escape rather than just tiny vents that semi work, and that's always worked for me to keep from getting air/gas pockets in my castings, maybe that will help next time. Hammer looked great.
The hole looks like a shrink. a riser opposite the sprue should move it out of the part. There's always a shrink. the idea is moving it out of the part. No guarantees though, that's why they make welders. Nice job. 45 years in a bronze foundry . Gloves, mask, and spats might save you a lot of pain.
I make wooden cores and they work well...i beleive a piece of sand fell in the mold and the metal ran around it and made the hole but im not an expert by far.
Hey Ron. i'm pretty confident it was shrinkage. I didn't have anything in the part that would indicate sand broke out from somewhere else. I fixed in in a later video by adding huge ;-) feeders on each end.
Love the hammer even with the hole Maybe put a magnet in it to start a small nails Old timers would steam the wood then add the wedge like shovels handle to bend into shovel
Thanks! If you watch the next video, you’ll see it was actually due to shrinkage and not having feeders to supply the head as it cooled. I managed to get it right the next time around ;-)
Very cool project. I definitely need to try making some AL bronze. For your molding/casting difficulties, I urge you to look up sandrammer here on youtube. He's a retired Navy foundry man and covers in depth how to go about creating molds that have the best chance of succeeding.
Its definitely shrinkage not an air bubble. Aluminium bronze is a difficult material to cast as it suffers from tenacious oxide skins that look like folds in the surface of the cast part but unfortunately inevitably go right through it if casting technique is bad. Also being a very short freezing range alloy it is very prone to developing large shrinkage cavities at hot spots in the mould. Careful rounding of gate /casting junctions is necessary to avoid this as is the provision of an adequate feeder. The feeder needs to be big enough to still be at least partially liquid when the casting has solidified. Obviously this means that the feeder must be bigger in diameter that the casting, at least 50% bigger. For best results the feeder should be about 1.5 times as high as it is in diameter. One must never pour down such a feeder instead a separate SMALL sprue should be used to take the metal down to a runner that connects to the base of the feeder and the feeder then via a largish gate to the casting. This is important with all metals but particularly so with difficult materials like aluminium bronze. Many of my videos demonstrate this. I have cast thousands of aluminium bronze castings in a number of different alloys. For hammers I would suggest CMA1 bronze, it is heat treatable and will get surprisingly hard, it is a much whiter colour more like nickel silver. I would have thought the vents unnecessary.... Martin
Honored to have you reply. Several people have sited your channel as a reference. If you can, I'd love for you to watch the video that comes out in a few hours. I think I'm headed in the right direction. I did not make my risers as large as you suggest, but their placement in relationship to a tapered sprue I think is closer to what you recommend. Again, thanks for the feedback.
I await you next video with interest. I too hope to have a short video out in the next few days. It will show a lovely little casting produced with close to what is now thought to be optimum gating, decent pouring basin, small tapered sprue, adequate feeder etc. The casting is aluminium but that does not matter as the gating style is valid for most castings in most materials.... Martin
You could probably just carry your tub of sand and casting box inside to warm up and put it together in the shop and if you need to carry it back inside till the pour
That would be the smart thing to do, I just never seem to think about it a day in advance. I watched a younger guy do a hammer after Paul and I did. He brought his inside to warm it up.
SWDweeb, William is right. Longer gate, fatter sprue. A fatter vent doesnt hurt either, if it can, it will pull from both ends, which reduces the tendency for bubbles. The sand breathes, so even if every hole is plugged with metal, if the vent and sprue solidify too fast, it will pull air into the area from outside the mold and make a cavity, which is likely what happened given the hole's shape. Basically if you make both sprue and vent fatter, with a larger gate, it "feeds" the mold area for a much longer period, till its solid enough not to make a cavity and holds its shape as it shrinks. There are 2 stages of shrink. Liquid and solid. Liquid shrink is drastic, it shrinks a lot. Solid shrink is less but its still there, and significant in precision parts. If you can feed the mold cavity long enough for at least the outer area of the hammer to enter the beginning of the solid stage, you'll get much better results. Remember, you are gravity casting here too, so the more metal above the actual part's highest point, the more is presses down into the mold, which aids feeding. Basically, If one solidifies before the other, it will pull from the other, if both solidify, it will pull air. You want it to pull from both ends. You can make towers with a soup can and stuff it with casting sand. Get a funnel, put it upside down, put can on top (after cutting a hole in each end of course) and stick a pipe of the desired diameter inside it. Pack it and keep it as upright as possible, its ok to correct it as long as you continue to pack it down. Flip it, get the forms out (pipe and funnel) and place it on top of the vent hole. Careful of the weight if theres a cavity under it, dont use a massive can like Chunky soup if you have a situation like that, use a normal Campbells one lol. The funnel isnt "as" important as the pipe diameter, as long as it fills the base diameter of the can. But back to placement, just gently put it up there, dont push or anything. If you feel more comfortable you can make a mound around it as a sort of gasket, but its usually not necessary. Those extend your mold beyond the capability of the box, and give you the bennifit of having tall risers. I use them in my bronze sword castings, which are very thin and 33 inches long, so its a casting nightmare, but that technique (among others that I wont divulge) are what make it work. Hope that helps. Let us know how it works. Another trick is to make smaller risers in the center area of the length of the mold, above the part. This is a cooling technique to use with fatter risers and vents. What happens is those solidify and act as a heat sink to solidify the part faster which means, of course, the feeder areas dont need to do so for as long of a period. This can affect crystal structure in some metals but I dont think aluminum bronze cares since its fundamentally different from the other bronzes (an arrangement of atoms, not a new molecule). Cooling techniques like this come in very handy in large castings, where you simply cant make the sprues and vents any bigger.
Thanks for taking the time to write that lengthy reply. I appreciate you doing that. Have you seen this video? ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MsW4G-J2LA4.html I did it the following week after getting a lot of great information like what you wrote. I've learned a lot more since these were shot and think my gating/feeder/sprue technique has improved quite a bit since this video. If you have time, check out some of my newer videos and let me know what you think. Thanks again for the info.
No i havent seen the followup, ill watch that on my lunch break today. And welcome. I tend to write freakin essays when im trying to help someone, the whats, whys and hows of stuff. Hopefully it was helpful and not too painful to read through,
:-D No it wasn't painful to go through. I had no idea how much there was to learn when I started casting and I find it fascinating. FWIW, I have regular email communication with Martin (olfoundryman) and he has taught me a lot. Well... he's imparted a lot of great information "taught" implies that I've learned and implemented what he's said. I can't say I've done that yet but I'm trying to and I think I'm moving in the right direction.
Really enjoyed your video. I saw Paul's video first and learned about your channel from there. Could you clean out the void and remount it in the greensand so that just the face is pointed up and then pore just a bit of molten metallic in to fill the void? You may have to regrind the face but it beats having to recast the whole hammer.
I've thought about that but am planning to recast the whole thing tomorrow (not necessarily the same thing as remelting) with a lot of the things I've read in the comments the last couple of days. I'm hopeful that go better the second time around.
I'm learning that. I actually re-poured the hammer using better feeder tunes (risers) and it came out much better. I have a video of it here ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MsW4G-J2LA4.html the shrinkage is really evident in the feeders. The video I have coming out tomorrow shows it as well.
I'm not a metallurgist and I don't know if a water quench would do do anything bad. My assumption is that the crystalline structure would be affected and that it would make it more brittle, but I have no idea.
@@swdweeb it’s actually how you anneal it (quenching in water). If you work harden it, you can make it soft again by annealing it. Kind of the opposite of hardening steel.
That god damn hole! It would have been such an amazing looking hammer too.... ah well, still a great showpiece....... Now we just need Tito4re to join in and make an aluminum bronze hammer, with an aluminum bronze handle too lol
aye, and then he still finished the video lol.... but to be honest, his casts arent really as detailed as this hammer you did for example - was shocked to see how much more intricate yours was after coming from pauls side
Ok I can explain but it will take some typing... What happened is that the thin sections beside the core(cheeks?) and the vent at the end with the shrink detect (after it filled with bronze), froze first, and began to shrink, sucking still-molten metal from the nearby thicker (therefore hotter) section and leaving a void there. You were right to use a skinny sprue (instead of a fat one that might have doubled as a riser) because a fat sprue causes turbulence in the mold and al-bronze can turn into drossy foam when that happens, but you also needed an even thicker riser to feed the shrink in the hammer face while it fed the vent and thin cheeks. This consideration in mold design is known as directional solidification. There's an example in my al-bronze axe casting video, my riser had massive piping on top which would have ended up as a big shrink detect on my axe if it hadn't ended up there. You might have saved it or made the defect less catastrophic by not allowing the vent to fill; I use a 1/8" welding wire sharpened at one end to vent greensand molds. I try to just push it down near to the pattern so that steam can escape from the sand, but it's sharpened so that if I actually do touch it, it doesn't make a big enough hole to allow metal to pass. A vent can't let gases escape if it's full of metal anyhow, and petrobond doesn't make steam like greensand does anyhow. So a vent that does fill is not only not a useful vent, it can actually cause or worsen shrink de defects... It's quite likely there is a void of some kind hidden inside the other end of your hammer as well. The solution would be to use a riser for each end. This worked for me when I cast a double-bit aluminum bronze axe a couple years ago, before I started filming my casting sessions very often. Great job polishing it up and designing the pattern though! You're lucky to have access to 3D printing, I'd love to try using printed patterns. I probably would have had to vote for your hammer over Paul's if you hadn't had that shrink right on the face, gosh what a shame!
swdweeb TL;DR: if I am right that it was shrinkage, the way to avoid this is to use risers to feed the thick sections of the casting as it solidifies. There are some other good suggestions here as to what may have caused it which may be correct, but my money is on shrink. Was also thinking maybe someone with a TIG welder could use your cast vent as a filler rod to repair the defect.
swdweeb good luck and let me know how it goes if you try it, my axe has a little spot that needs some filler too but I haven't yet been able to get in touch with my local TIG guy...
Shiny! I'm just a hack ameteur, but I can venture a GUESS as to how you ended up with a bubble in your hammer's face. In a video by Jim Taylor, he uses a "well" under his sprue to stop (or reduce) turbulence. Another video I saw used longer than necessary gates to slow down flow speed. Olfoundryman takes great care to round off where spires and gates change direction (I assume for the same reasons, but he didn't actually say.) I don't see many gates that are short or straight in the videos of the people who get the best results. Maybe you could investigate that area further. Myfordboy does a pretty good job of casting, too, as does Brian Oltrogge. It might be helpful to you to see their videos and maybe read their comment sections.
One other pretty good resource that I forgot to mention is mrpete222. He has a 10 segment casting series with the first 5 about making the patterns only. As a former high school shop teacher, he seems to be pretty knowledgeable too. He has videos on working with a lathe, forge and other machines too. I think he has made over 800 videos now.
I only watched a brief bit of the vid just to see the results (sorz) but i think that whole at the end (just shooting in the wind here) may be a cavitation bubble when it cooled.
:-D everyone does that. That's exactly what happened. The feeder froze before the part cooled. During the cooling it shrunk and with the frozen feeder, there wasn't any metal available to fill the void.
Hmmm... that may be a tough one. I had a friend model and print that pattern for me. It was before I had the ability to do these things myself. I don't have the files. I'll have to check to see if he kept them. Don't hold your breath, he's not one to save things like this. My aluminum bronze ratio is typically 90% copper 10% aluminum by weight
@@swdweeb I ask because the flow of the design I can’t seem to find anywhere, every ball peen/pein design I find I don’t like to modern where as yours has that vintage/fantasy look about it
I'm going to argue, but understand that I know NOTHING. ;-) It appears to be a bubble in the middle of the cast, not shrinkage. My assumption is that gas, maybe air, got sucked into the pour and couldn't escape. Keep in mind, I know nothing and I acknowledge that you could easily be right ;-) Thanks for the feedback!
swdweeb very possible but ive seen the smaller spure cools before the larger mass of the hammer escaping gas floats to cold sprue and stops a larger sprue lets it stay molten longer allowing the gas to escape the part and go into the sprue so i think a combo of both issues is causing the holes. Great video btw allways on the look out for good channels
Interesting. Thank you. I had another comment talking about gates being large enough to prevent cooling along the way. I'm definitely looking tin to larger conical sprues and risers for future pours
apparently you've never tried to drill or tap aluminum bronze. 😁 Its really hard stuff. The only way I can cut it is with abrasives. I also dumped that hammer at least two years ago.
Wow, that is a challenge. Right off the bat, the handle seems to be the hardest part. It would have to be kind of "S" shaped or something. A loop just wouldn't be possible. At least I don;t know how I'd be able to do it. I don;t think the "boat" part presents that big of a challenge, but the handle... I'll have to think about that one.
I looked at some gravy boats online yesterday, they'd all be impossible for my knowledge and skill level. A spoon however... I think a spoon would be very doable.
I did see this one, a variant on the grip might be doable but it was the only one that I saw that I think I could do cdnimg.webstaurantstore.com/images/products/extra_large/17341/1019837.jpg
Suck back. Well, that's what I call it. I see in another comment a well said explanation for the lack there of with material. The comment about the "riser". I'm such an amateur with all this. I like to cast though. I usually use foam and green sand. Sometimes I vent but most of the time it's just the piece I'm casting with a sprue attached. I have a couple recent videos. Again...pure amateur. Nice hammer though. I tried to pour a hammer head...well. I tried to use a cope and drag that I built...couldn't for the life of me get through the first process...sad face. I'm pretty good at a bunch of things...building a cope and drag is and was not one of them. 😁
It's definitely shrinkage. I have a follow-up video where I fix the problem ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MsW4G-J2LA4.html . If you're interested in hammer heads this was a big one that I cast for a friend ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-4go8EJE6HpQ.html
Yeah, i thought about that. Even thought about trying to get someone to TIG some of the scrap back in. I cast another and it came out great ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MsW4G-J2LA4.html so I'll probably just hang this one on the wall ;-)
IMHO: It looked as if your sand was way too dry! I thought that it had to be slightly "damp", and, that it would adhere to itself a bit better. (like building a sand castle). You cannot build a "sand castle" with DRY sand!...
True, but the mold came out fine as you can see in the finished casting came out great except for the void which was a rider problem not a sand problem. So far my petrobond has maintained its ability to hold together. I've started not mixing the burned sand with the not burned ti ensure that is stays that way.
Multiple people suggested that and almost as many told me it couldn't be done. I simply recast it using a better gating system ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MsW4G-J2LA4.html to prevent the void caused by shrinkage.
Remove hammer head from the handle. You'd be doing that anyways if you want to change the wedge. Wrap the hammer head with a piece of tin from a tin can to create a 1/2 inch high damn around the holey end of the hammer. Clamp tin with vice grips. Preheat the hammer head. Melt pour material and fill the casting hole in the hammer head. Cool, remove tin damn and regrind to shape. Shazam! No hole! And yes, the molten bronze will melt the surface of the hammer head and stick just like it would in a brand new pour. Hammer salvaged and completely usable. Have fun. OR you could just pour a string of material into a wire shape and use M.A.P. gas torch to weld and fill the hole shut. Both options are about the same amount of work. Both work equally well.
Thanks Ed, You've almost got me convinced to try it. ;-) I learned a log from this effort and may have another option. Check out the video that will come out this Friday and let me know what you think. One question, if I heat the head, how hot would you get it? Just too hot to touch or almost melted? Still lots for me to learn here.
Definitely too hot to touch but don't melt it. The molten metal will melt the "surface" of the casting as soon as it touches it when you pour. The only reason you heat the casting is to lessen the shock factor (hot on top of cold) which can cause a fracture to appear between the casting (the hammer head) and the new pour on top of it. You can add to a casting after the fact. Lets say your casting is too large for one pour. Then do it in two pours. Just don't take so long to prepare the second pour that the first pour cools down too much. This will only work in an overhead pour however, where the sprue and the gate can completely drain and remain open to accept the second pour on top of the first pour. After dressing the casting, you'd never know it was done in two pours. I'll tune in on Friday.
You know I watched someone else do that. I'll have to give it a try on the next one. I'm seriously thinking of recasting it this week just to try all of the the suggestions I've gotten. Thanks
If I were you I would buy some Styrofoam and insulate that garage door, I have 2 12x12 doors I insulated and my shop is kept at 70 degrees and it is 16F outside right now. Having a metal door you are not going to be able keep the heat in at all. You might care to check out the Olfoundryman channel and Sandrammer channel
I've thought about that from time to time (the insulation) but never seem to get around to doing it. Maybe its finally time ;-) Thanks for the channel suggestions. Someone else also recommended sandrammer
You know, I know that. Do I do it, no. Should I do it, yes. I think I've been holding out until I reline my furnace. It's a lame excuse, but it's all I got ;-) Thanks for the advice.
Absolutely wrong. The sprue is designed to conform to the shape of the metal as it falls thus preventing air from being entrained in the metal as it is moving. Sprues should freeze off before the part freezes. If you want to feed a part then use a feeder that is sufficient to feed a part in the location it requires it. This hammer was a long time ago and I learned the lesson of feeding it properly after making this mistake,
Thanks. It's ok, the nice thing about it is I can always recast it. I've gotten a lot of really good comments for me to try on the next pour that I'm going to do.
Its sand, not mud. You do not want your molds to be "air tight". If they were, expanding air from the hot metal would have no way to escape except back out through the sprue (the entry hole as you call it). That would be a huge disaster.
I could have but I only heard about pattern boards a little more than a month ago. ;-) I actually have a video coming out soon that I use a match plate on.
Have a look at the old foundry guys videos, ru-vid.com/show-UC90RoN_IjSRF18jAG0HIA6g. He has some good info in there on casting, sand prep, rises, vents etc, well worth the look, click the play all button to see. Also this young bloke has done a similar project with the sand you are using in similar temps, good idea for next time, ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rNP5UKnY03I.html. Your workbench is as cluttered as mine, my garage is opposite to yours atm, roughly 95 to 100deg F and 90% humidity. Give this hammer another go after you have done a bit of research, you'll end up with a great usable tool, thanks for the Video.
Thanks. Check out ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MsW4G-J2LA4.html Yes, that young man did his after Paul and I did ours. He contacted us before he shot his video to see if we would mind. Olfoundryman and I talk on a regular basis.
