Hey all, new to the forum as well as casting. I'm trying to cast a saxophone mouthpiece out of brass, but have yet to get a good casting. The mouthpieces are hollow all the way through, about 4.5 inches long (included a diagram for easier communication) I'm using a solid flask with the straw method and a manual vacuum pump, Prestige Oro investment, doing wax burnout and melting metal in a homemade propane forge. Not an ideal setup but it should be somewhat feasible, right? Could I get some advice on what I'm doing wrong and how to fix it? My best guess is investment breakdown combined with poor vacuum pull? Not enough head pressure or bad spruing? One attempt shown is with the mold cooler (800ish F) which yielded something close, one is with the mold hotter which was worse. Any help would be greatly appreciated.
What was your spuring arrangement? It really looks like eiter your brass temperature was low, or low mold temperature...
Just one sprue to the beak. You can see it better with this one (flask for this one was glowing hot). As for the metal, is burning zinc in the brass unavoidable to get it hot enough? I've been using borax but it still starts to burn when I try to heat it much past molten.
On the zinc burning, yes smoking is pretty normal. Some guys use a cover material like glass or carbon. I don't use a cover personally. Sometimes I add a bit of pure aluminum. It does seem to help clean up the brass and reduce smoking. Any time I have tried to flux brass with borax, it has produced unfavourable castings, so I don't try any fluxes any more.. For your next pour, let it smoke and dont flux and see how it goes. But use clean metal. If your melting scrap a soak in 10% sulfuric acid works wonders prior to melting. A gating strategy would help too. Typically gating into the bottom of the casting and venting from the top works best.... What was your source of brass?? Not spent shell casings I hope???
everything David said +1 !!! as probably the most prolifiac brass caster here, I'll chime in with these notes https://www.normans.co.uk/blog/2014/05/difference-brass-finish-make-musical-instrument/ Shoot for the 70/30, it is a good alloy and easy to work with , you will need to replace the zinc being burned out, you can do that in the beginning, by placing about 5% extra zinc in the Melt, Newer U.S. pennies are great at 95% Zinc, with a copper plate of 5% ( yes this is a crime in the US,) so dont make it a production process, But for a quick and dirty process it is perfect, Or you can Plunge 5% Zinc just before pouring. dont sweat the possibility of getting in too much Zinc as 60/40 is a great alloy , adn if you go the other way your good save for color , just try to work with a good starting metal to avoid lead and Sulfur , (already mentioned) , Brass shell casings are the perfect 70/30 alloy, but the sulfur residue from the gunpowder is a terrible contaminate if you should have an opportunity to go that route, you need to remove the primers and clean the casings, Vibrating or sonic cleaning bothe work V/r HT1
If someone gives you a bucket of .22 rimfire casings check they didn't throw in duds that didn't fire! (That was a close one) I agree with Jason, silicon bronze in a shell, oh woopps, he hasn't posted yet Edit: I used to drop small lumps of charcoal into my brass melt as a bit of a cover, not sure it is a desired practice or a waste of time?
True sort of, there are exceptions to the prohibition on melting pennies: Whether this exception might apply to you in this case, you'll have decide for yourself, although in my non-professional legal opinion, using pennies solely because they are made primarily of zinc would probably mean you are attempting to profit from the metal content of the coins and thus would be illegal.
Interesting project and a challenging shape. Is this for fun or do you intend to get a usable mouthpiece? Metal sax mouthpieces, and many hard rubber and plastic ones, are machined from solid stock to very high tolerances. Especially that inside chamber where tiny differences make a huge one in how it plays. Most are machined by CNC but there's also a small number of hand operators still around. Here's a few examples. https://video.search.yahoo.com/vide..._20_19_ssg08&sdk_ver=&cd=&cr=&uid=&uref=&tt=b https://video.search.yahoo.com/vide..._20_19_ssg08&sdk_ver=&cd=&cr=&uid=&uref=&tt=b https://video.search.yahoo.com/vide..._20_19_ssg08&sdk_ver=&cd=&cr=&uid=&uref=&tt=b
It is my understanding (not lawyer, but collector and occasional melter of coins) that if you aren't melting them for commercial purposes (i.e. making money at taxpayer expense) it is legal to melt them. The provision is, as I understand it, to avoid issues with seigniorage and the like. I got my understanding from reading information at the US Mint's site. Coins no longer intended for circulation can be melted at whim (silver coins, etc).
Okay thanks everyone for the input! Will try this stuff for the next pour. I have been using 70/30 ish brass made from a chunk of garage sale copper and modern pennies. I do have a little brass from shell casings but have kept it separate haha. Any recommendations for where to get brass or copper? Is it worth it to buy stock or does scrap work fine? This is for fun but I am trying to get a usable mouthpiece, I realize most modern ones are machined, but I don't have the equipment. There are some makers that use investment casting, but don't reveal their processes.
So I did another pour, got the metal much hotter with no borax and filled from the bottom of the casting, vented from the top. Got a much much better casting! Still had some porosity where the sprue fed in, is that my design or something else? In the olden days mouthpieces were cast, not so much anymore.
