So I finished up investing the two prints and burned them out. Much better results on the shells but still had some trouble on the yellow brass pour which was mostly my error. I should have spent more time on skimming the melt and heated the shell up hotter before the pour. Hind sight is 20/20 they say. i knew I had made an error on the first pour, so I went hotter on the second and spend more time on skimming. That gave me the results i was hoping to see. There is a bit of a learning curve with switching processes, no doubts there! And I could have easily done these castings as a bock mold. So maybe its time to go big or go home? Time will tell LOL.
Looks pretty decent to me, and far better than any brass or bronze castings I have done. I have never had any luck with brass or bronze. All I get is a bunch of heavy smoke and slag.
Alot of people do. Makes me question what it is that is making the difference. Did I just hit the that magic furnace environment by accident or what?? I know that when I shut down the burner, things change...I can see that, and it is the o2 levels that are effecting things. Even going from a half full crucible to a full one on a windy day, yep Notable difference. Oxidation is a bitch..
Here is some of my better brass/bronze work. I have had all sorts of trouble; gassing issues (no I did not use a degasser, but should have), partial fill (melt not hot enough), and when the melt is heated to get it towards pour temperature, the smoke gets so extreme that it catches on fire. Nightmare stuff every time I tried it. I have had much better luck with iron than brass or bronze. I suppose that if I put the same amount of time into troubleshooting brass/bronze problems that I have put into troubleshooting iron and aluminum problems, I would have better results, but I really got disgusted with brass/bronze, and I use those ingots as boat anchors now.
Maybe this will help you out, Molten brass hates air. I use smaller crucibles and I dont fill them more than half way full, this keeps the wind off it somewhat. I try to do all my skimming while the furnace lid is closed and the furnace is running, the furnace environment keeps the zinc from igniting (lack of oxygen - reducing atmosphere) Once the melt is clean I try to move as quickly as possible, I shut down the furnace and as soon as I do the molten brass will "flash" creating a layer of an zinc oxide (fluffy crystalline stuff) that seals over the melt but is easily disturbed so move quickly but smoothly to the pour and pour fast and hard. I dont usually flux or degas either, seems to hurt more than it helps. No covers also.
I have never had a gas issue with a true Brass... Manganese bronze is another story. I suspect wet sand is Patj's issue.. which i find odd since I know he has no problem with cast Fe... V/r HT1
Not to hijack David's thread, but I had I had some scrap yellow brass, some manganese brass ingots, some red brass ingots, and some naval brass in the form of some very tough boat shaft. Melting this stuff was done early in my beginning foundry days, and I really had no clue about much of anything related to a foundry. None of the above metals I melted worked out. We can start another thread if we want to discuss it further, but suffice it to say, I admire the quality of David's pours for sure, having been there, tried that, and failing miserably.
lol pat, if you want to do brass, come up where I live, I'll show you all kinds of tricks for casting in brass. Alot of the parts in the steam engine build was done in brass and naval brass, so Ive had my share of brass casting, lol.
are you sure the shaft was Naval brass and not manganese bronze??? Manganese bronze is very difficult to cast successfully unless you know what you are doing V/r HT1
