Couple things I poured today. Not the best as I knocked a chunk of sand loose during transport or closing the mold. Need few more melts with the blower to get it dialed in.
This was yellow brass... scrap pieces out of flat stock...1/16" to 1/4" thick. I do much better melting thicker brass....when I use only the thinner scrap pieces I get a ton of slag/zinc. On this particular pour I wound up with half my melt weight in slag and only poured two molds as the rest was trash. I am sure I am doing something to cause this as it seems to be better some days and worse on others. Sure it is related to heat and time. I need to get my thermocouple set up so I can see the temps. and see if I am too hot or not. I am not doing any more brass til I get it set up. I have the temp gun and wire...guess I could use it like that til I get a ceramic thermocouple cover for it later. Right now, it seems for me, the best method is to fill the crucible and to not touch it until I see everything go into solution and pour immediately...seems if I try to slag it out before pouring I just create a lot more slag. I am beginning to not like brass.LOL This is the part where only being in an industrial setting with the same metal is becoming a handicap.
Perhaps put a cover on the pot? (What I plan to do, even if red/dread brass is more my inclination). That, and have something like charcoal to compete with the zinc, etc. for Oxygen? Ammen speaks of using charcoal in "Casting Brass". lmine.com has crucible covers. https://www.lmine.com/crucible-covers-c-1_2_504/ Smallest goes fine on an A4 salamander, unless they are lying... "This be Dread, Mon - Dread Brahh'ss." (Saying in (fictional) Jamaican Foundries)
why does everyone have such trouble casting Brass??? 1) how long from the Time you put heat to metal til you pour??? more importantly from the time you get liquad til you pour, this time needs to be limited 2)is your metal clean??? is it Lacquered?? 3)Are you getting slag, or Dross? slag is glassy, dross is powdery and crumbly 4) How big is your crucible ? you will have more trouble with dross in brass with a smaller crucible not the A# some A# have went metric 5)are you sure you are getting a neutral flame in your furnace , lets circle back to your metal, 6) are you sure you are using brass, any chance you mixed in some brass plated Zamak ??? that il cause you some serious dross, if you get the zinc content over 45% Brass is super easy to work with it melt it , add a little make up zinc, pour and yes take your own advice and stop pourin til you can take temp readings, right now your results look like you are WAY overheated , or you are using some FUBAR green sand V/r HT1
1. Roughly 30 to 35 minutes from start to pour. 2. Yes...nothing on it at all. Could be high zinc content...used for patternmaking and engraving. 3.Dross. Definitely powder. Almost like half the melt never goes into solution but instead turns to powder. 5. No...I have only melted with it a few times and have been trying to get it dialed in. I think I got it about right on the last melt as it seemed to melt much faster and with less gas pressure. 6. I think this is the issue. When I used a big bearing I cut up that was a different brass in about 3/8" thick chunks it all went into solution like butter. When I mix the two together I can tell the thinner stuff does not go into solution but just turns to dross. the temp could also be an issue...I would need to be able to adjust the heat better and with the current blower I am using i am afraid that may not be so easy...even on low it may be too high. I run it on low as med and high just way overkill. What temp do you like to reach before you shut off the burner? Also I do notice when I melt more mass i have less issues...smaller melts suck.
I meant to reply to your post earlier but I see I did not. I meant to mention the sand is synthetic..it is good...the print I made the piece off of was awful and the sand did too well in showing the flawed surface...even at 18 degrees in the building where I was molding.LOL All of these models have rough surface finish off of 3d printer due to changing the size of the graphics to fit my needs. I need to try to get the graphics better before printing but I have been unable to do much with them yet. This was my third attempt to clean up this model and I finally decided it would be easier for me to cast it and work with the casting.LOL
ok one last piece of advice: when you load your crucible you want some thing nice and solid on the very tip top, so put all your small stuff in the crucible , then put some large piece of scrap ( A pouring inverted basin works well for me ) this large piece of scrap acts sort of like a crucible lid, as the furnace gas cannot interact directly with all the small pieces which have lots of surface area to oxidize V/r HT1
