Ok, I am new to casting, so please go easy. Yesterday I tried my first cast using brass and a sandcast mould I made of a 3D printed name plate. However I was so pleased that the cast went well I forgot to empty the crucible. The crucible is the type that fits into an electric furnace. There is a fair bit of brass remaining at the bottom of the crucible. I have read that I should not try to reheat the brass as it will break the crucible. Is there anyway that I can remove the brass without breaking the crucible. And if it does break within the furnace am I correct in thinking it’s game over for the furnace also. Thanks, m
How big is the crucible and how full? You're probably SOL but you might try placing it in your freezer, or dry ice. The colder the better. The metal will contract more than the crucible and if you turn it upside down and wrap it on a block of hard wood while still cold, it may pop out. At this point you have nothing to lose. Good luck, Kelly
Thanks for getting back, it’s a 3kg crucible, remaining metal is 1 1/2 inch from the bottom. I will try the freezer tip. But have also ordered a few 1kg crucibles. I found that the 3kg was just too large for the parts I need to cast. .thanks.m
I'd be interested to see if freezing it causes it to crack. At least in the case of silicon bronze it wets the interior of the crucible and sticks tight unlike aluminum. Pete
Just an update. Went out to the workshop today, had a look at the crucible. Too my amazement I found that the metal was free moving at the bottom of the crucible. I was able to just slide it out. However it looks like my luck was down to the brass being not a good quality material, but a cheaper mix with a high level of zinc. Surrounding the metal was a lot of white zinc powder, it looks like the metal on heating up had burned off some of the alloy mix and had reduced in size on cooling down, so not sticking to the crucible. However I am not sure how having a high zinc level will help or not in casting the material. But the crucible is saved to heat up another day.
Could have possibly been temp related. It would be better to have pics but the first melt I did with brass I thought the same thing....poor metal quality..but on my third melt I decided to melt some of the same material and at a higher temp it went right into solution and had almost no slag. I also over heated my brass once and just got horrible shrinkage but not the powder so I would think you are probably just on the cold side of going into solution. My camera is AFU right now or I would take pics so you can see what I mean. One thing that does sound like you were possibly close to right temp was the shrinkage you got.
