I need some expert advice again. I’ve been setting up my own studio, looking up discussion threads on various websites for ideas, and settled on an acetylene/air torch for my little jewelry business. Not doing any annealing or small earring work, just melting silver and bronze for casting rings and small pendants. I’m even taking a Lost Wax Casting class to get the torch experience. Now, they use an acetylene/oxygen setup there, and that went just fine on our first casting session. I asked the instructor about my acetylene/air setup and they are saying that aceylene/air won’t be hot enough to melt silver or bronze with any degree of success. I guess i missed something in my torch search, so what am I missing? Will acetylene/air work for what I do, or do I need the acetylen/oxygen system?
Thanks in advance.
Quick question. Are you considering vacuum casting or centrifugal casting? They are different set-ups and have different start to finish time issues.
Your instructor is correct in that air/acetylene takes longer to heat an equal volume of silver or bronze than oxygen/acetylene.
If you want to get a feel for how much metal that you can melt with an air/acetylene torch, I’d recommend melting and hand-pouring silver and bronze ingots first. Maybe in your class, you can cast some ingots with different amounts and types of metals with an air/acetylene torch and an oxygen/acetylene torch to compare?
Let’s see what others say.
Jeff
You will get frustrated trying to melt very much silver and especially bronze with an acetylene and air torch. Look at acetylene and O2 or even better propane and O2. If all you are going to do is cast, you might look at an electro melt furnace with separate crucibles for each metal. You then could go with a much lighter torch for any fabrication work that you would do. Good luck…Rob
Lost Wax Casting, with both silver and bronze, in a centrifugal casting machine (an old Kerr specifically for jewelry casting). Thought I’d done my due diligence and natch…
Not doing any ingot melting or hand pouring. Haven’t gotten that far yet, if ever.
Looking for a Smith Little Torch setup now.
Thank you. The responses I’ve gotten have verified my situation. Looks like I track down an oxygen tank and new torch…
Looking back at a previous post of yours, I see that you have an old dental centrifugal casting machine. This means that you’re only going to able to cast small flasks no matter what right?
I think you should try out the set up that you have, including your air/acetylene torch and see if you can make it work for you. You’ll probably want a bigger torch at some point, but for now you don’t have a bigger torch. So I’d practice with what you have. Are you trying to have fun and learn or are you hoping to go into production to sell stuff? Those are two very different perspectives.
Assuming that you want to try this, here’s some tips.
Don’t cast more than a 1/2 ounce. You should be able to make some cool ring-size pieces with up to a 1/2 ounce.
Before you burn out your flask, balance the arm with the metal, the crucible and the flask.
When it’s time to cast remember that the first phase of melting metal in a ceramic crucible is to heat up the crucible. Get the crucible hot enough to melt flux before you put the metal in.
It’s helpful to have two people, but not required. One person melts the metal and releases the arm when all is ready. When the metal is almost melted, the other person takes the flask out of the kiln and puts it in the casting machine cradle. It’s the metal melter’s responsibility to make sure the crucible and flask are connected and tight. The idea is that soon after the metal is melted the metal melter person can release the arm.
If you don’t have a helper, you can do it all yourself. I’ve done this by myself countless times. It’s just easier with a helper. When I’m by myself, I arrange the kiln to be in a place that’s close to the casting machine. Often I’ll even unlatch the kiln, so I can open it quickly.
I’m a big believer in practicing, practicing and then practicing some more. I recommend going through the motions of the entire process repeatedly without actually casting anything. This way when it’s time for the real deal, you can rely on muscle memory to aid your brain in remembering all of the steps.
What kind of a kiln do you have? You do have a kiln don’t you? How are you going to invest your flasks? Do you have a investing vacuum machine?
Up to you, but I think you should give it a try. What have you got to lose?
Let us know what you decide!
Jeff
You might consider buying a wand type crucible. They are fairly inexpensive. Then just experiment with your current torch and scrap silver to see what you can readily melt. Pour the melt into water or a groove cut into a charcoal block. You might just get an ingot that you can process into finished metal. The goal here is to see how metal behaves when it melts. There is a lot going on and, as described by Jeff, you will wish that you had more than two hands. With practice, you will get to where you are comfortable being able to safely melt metal and pour it into an ingot mold. Pouring onto a centrifugal casting machine is a step up in practice and aggility. Once you get here, please make sure that you know all that can go wrong and have compensated in some way to avoid it. I am pretty sure that by then, you will have moved on to a torch that produces more heat as it is heat, not temperature, that melts metal. Stay in touch, report your progress and good luck…Rob
the VOLUME of gas makes the difference. air/acetylene burns very hot… low heat output torches due to low volume of gasses won’t do the job of melting large batches. A high output torch will do a good job of melting. I’ve always used my oxyacetylene torch with a steel plate cutting tip to do melting. The heat output is very high… this set up is for steel cutting and welding…can’t be used for soldering and fabrication as the flame is too large and hot… it does work extremely well for large batch melting. For smaller torches will less gas volume, a hotter flame would be better. I would go with oxyacetylene. The set can also be adapted for oxypropane. regulator pressures and the knobs on the torch can be adjusted. Heat output is still very high.
Actually, I went ahead and returned the Kerr dental spinner and got a Kerr jewelry spinner with a longer arm for larger flasks. It’s all set up and ready to go.
The kiln is a Tabletop Hi-Temp burnout oven. It’s not the programmable version, just the basic kiln, so I’ll have to manually raise and lower the temp during burnout.
Picked up a vacuum chamber, investment, mixing bowls, measuring cups, a cheap coffee pot to heat water for investing, torch starter, all the oddments and ends.
As for the muscle memory practice, yes, the instructors have all suggested going through the whole casting process without actually casting to get the steps down.
Everything is all set up so things are within reach of each other, the kiln just a step or two from the casting machine.
I’m going to try to hijack my wife and daughter to help out during the process so they can both assist and see what all this alchemical insanity is all about (cue mad scientist laughter…).
I’ve ordered a used Smith Little Torch (and No, NOT some Chinese cheap knockoff - I’m really starting to hate Ebay for all the cheap Chinese crap they try to pass off for the real thing)) and a new hose set for it. Just looking around now for an oxygen tank and gauge.
So, yeah, I think I’m ready. Just waiting for the last few things to arrive…
I was going down your list of things that you’ve purchased. The only thing that jumped out at me is a coffee pot to heat water for investing. I know that some people do that to speed up the process, but I was taught that investment is designed to be used with room temperature water.
I started doing lost wax casting in the 1970’s. For a long time, I invested pretty much by eye and intuition. At some point, I started following the manufacturer’s instructions. These days I use Ransom and Randolph Ultra Vest.
Here’s their instructions. This info could be helpful for you.
Ransom and Randolph also has an investment to water ratio calculator which takes out the guess work.
It sounds like you’re going to have a lot of fun!! Keep us posted with your progress.
Jeff
I second what Jeff said about using hot water to mix investment. It will speed up the chemical reaction, and you will have less working time. As it is with room temp water, you only have an 8-9 minute window to mix, vacuum the bowl, pour, and then vacuum the flask. Good luck.
~AJ