this isn't the project that I have in mind but its a simple way of explaining my question. If I were to cast a rough knife blank could I then work it over the anvil to create a functional knife?
Yeah, bronze is the way to go for cast blades. I have seen pictures of modern bronze swords that are 100% forged, not cast, but I have no idea how hard it is to do that as I only have a little bit of blacksmithing experience and that was with mild steel. Most bronze blades were cast. The aluminum bronze axes in the linked thread are cast, but they need to have their edges peened cold to work harden them or they deform hugely with even fairly light use. I grind them pretty much sharp then do the peening so that I can just sharpen them back up a bit with a stone real quick rather than risk grinding too much more (the work hardening only goes so deep). Peening can be redone after a few sharpenings. So there is some light hammering involved which is best illustrated in the video in what is currently the final post in that thread (the pipe tomahawk video). Maybe even better in some scythe sharpening videos, that's what I based my method on. I made another axe since that last post there, so maybe I will update that thread with some new pix soon. There is some evidence that cast bronze age swords had cold hammered work hardened edges too. Sometimes I even peen the whole axe head just because I like the dimpled look it leaves. I have not yet tried to harden one of my bronze axes via heat treatment. Unlike most alloys of copper, supposedly this is possible with the aluminum bronze alloy I use. Good luck! Jeff
ok, maybe I'm approaching this from the wrong direction. I want to make a thin disk shape, similar to a chakram, I was thinking that I would have to start with a thicker smaller diameter and work it until it was thinner and larger around. Maybe the question I should be asking is; what is the thinnest you can reasonably cast?
Depends on your casting method. You can get much thinner with block or shell using Vacuum assistance. You can get thinner in sand casting by pouring hotter but you can have more shrink. The metal you're using will also impact how thin you can go (like the alloy of bronze or aluminum, as well as if it's bronze or aluminum). Give use a little more info. And how thin you're looking to go.
Ok, full disclosure: I'm making a copper tophat. There isn't a specific thickness but I want it to be wearable.
Then your better off buying some copper sheet and forming it. But you can still cast yourself some matching goggles
Waaayyyyy better off. At least then you could wear it at a manageable weight. It'd probably be 10 lbs+ cast if you could do it......and it'd be a helluva challenge even for a very experienced caster. Best, Kelly
Copper works easy. After it's annealed, it's almost butter soft. Once it work hardens again, just get it red again. Over and over until you are done. If you want it to look rough, use copper pipe of different diameters and stitch it together with either rivets or weld. When I need a small flat piece of copper, I anneal a section of pipe, slice it lengthwise and pound it flat. Works great for backing up welds and filling in holes. I'm thinking patchwork style for your hat. Use clecos (https://www.mittlerbros.com/mittler-bros/metal-forming-hand-tools/clecos.html) to hold it together while you rivet. The hard part will be forming the curves. Look at the video below. Thin metal will be your friend here big time. Cast a copper top hat? NOPE! Couple reasons... 100% copper is a pain in the ass and it will be heavy as you will not be able to cast it as thin as you really need to. But it does sound cool. Hope you post photos of the build. Thak did a range hood like I'm thinking. He used a few different kind of metals on it.
Bummer, I was hoping to get away without buying much in the way of materials. It's going to be a lot slower if I have to buy stuff.
Hey Miles... I promise man, I'm not really trying to piss in your hat... Casting this thing would be a real bitch. If you don't have a tig machine, there are other ways to stick build a cool copper top hat. A propane torch and solder will easily stick copper together if the rivet look isn't what you want. Scrap copper pipe isn't that hard to find. Scrap yard or find a plumber and you'll get all the material you need on the cheap. No reason to use brand new copper pipe that's for sure. I do a lot of copper brazing with silver, but I need pipe to with stand 500psi. You don't have that problem. Shit, you could even use JB weld to glue the sections together by overlapping a 1/4". There are many ways to skin this cat. Once you anneal a pipe to red with a flame, a pair of tin snips easily cuts the stuff. It's all up to you how to shape the individual pieces into a hat. I will tell you buying copper sheet is VERY EXPENSIVE! Straight copper costs more than the bronzes and brass being the cheapest because of the lower copper content. Pipe is thicker and while being a little harder to bend and form, it will offer forgiveness for someone new and not break or crack as easily as thin stuff. As you work it, it will work harden, that's when you turn it red again. If your goal is the smooth top hat look, you'll have no choice but to find a large sheet. Mistakes could be costly and difficult to fix. You'll still have to attach the top and the rim too... Now if you are not planning on wearing this and it's just going to sit on the shelf.... Cast it, who cares how thick it is. Sand casting it will be really hard for a beginner with the easier and cheap option probably being solid investment. A 50lb box of investment isn't that bad. The hard part will be you still need to hand make or pull a mold of the hat. If you have a disposable hat, it could be coated with something to make it waterproof and pull a plaster mold of the hat in plaster of paris. Wax can then be sloshed in the mold cavity until you have the appropriate wax thickness (1/4") and invested in a big bucket of the investment material. After hardening, the wax is heated OUT of the investment block. Then it's FINALLY time for metal. Many people think of casting as cheap and fast. If you are crapping out cast key chains, it is, but at this level, it's time consuming as all hell and involves MANY steps. Disaster looms around every corner. Not to scare you off, but there is a reason many of us have been at this shit for years. I'm just a baby in the casting world. I've spent thou$and$ and countless hours of learning, researching, asking questions and a little bit of dreaming too. By hypothesizing questions such as yours, exercises the old neurons to come up with a suitable solution helps envision the process... This is the fun part. If you can't do the hat now because it's too complex or out of your budget, so what? Save the idea for a later date. Start small. Pick your process, be it sand casting in a box, dumping metal down ant hills or investment casting. Then stick with it and learn everything about it. Try stuff, make your mistakes, learn from them and move on. Each casting will get better as your skills improve. It's all up to you and only you can hold yourself back. I have been trying to create a super cool table lamp out of bronze... I've got the bronze part licked, but it's that glass work that has kicked my ass now for close to 2 years. I may not get it right this year, but one day it will come together. Doesn't bother me one bit to see the completed waxes collecting dust. I own the molds I created and that's good enough for me. Did you know Degas created a ton of waxes and only had one cast in bronze? He couldn't afford the foundry work! I'm no Edgar, but hell at least I can pour my own castings which is more than he could do! https://www.nga.gov/content/dam/ngaweb/press/assets/2002/new-sculpture-galleries/degas-waxes.pdf Wise man told me once, Money, Time and Quality.... PICK TWO!
That's what I've always told my bosses. I may have lucked into a source of scrap copper and brass for this project. I stopped to help a random stranger push his car to the side of the road. Turns out he just ran out of gas. K offered to run to the next exit and fill my gas can for him. When I got back with the gas we got to talking, I showed him some of my castings and it turns out that he works for a contractor and frequently throws away scrap copper pipe wire and brass fittings. In repayment for my help he's going to save some of the more choice scrap for me.
of course the trick will be to actually hear back from him. Most situations like that people tend to forget their promises
