The Shop > Composites & Plastics

3d metalcasting test

<< < (4/7) > >>

vtsteam:
Tom the white fumes and flames were zinc burning off from the brass. As John doubleboost said, brass is tricky compared to bronze. Temperature control and timing is important, covering the crucible can help, etc.

I have a hard time seeing what you are making in these photos as well as most others you post because they are so small. When I go to Photobucket to see if they are available larger, they don't seem to be. Just wondering if that's a problem with my anti-script add-ons, or if your photos are really just very low resolution. If they are just small, can you post them 640 pixels wide? Cropping to the object of interest and then posting the cropped image that wide would also really help

From what I can see, it looks like maybe you're casting a slide valve? I can't really tell -- or see surface finish of the pattern or casting. That would help figure out what's going on.

S. Heslop:
I suppose you already know, but it's worth repeating. But you should be careful not to breathe the zinc fumes. They can make you fairly ill, with flu like symptoms. There's even been cases of people dying from it.

Interesting thread though. It's nice to see people using 3d printers for useful stuff since i'm sick of seeing people using them to make ugly statues or things that'd be easier to make without one.

tom osselton:
Ok I never knew zinc burned with a white flame I thought it burned off as the white smoke, in the test melt the other day we didn't see the white flame. We are using the furnace outside so the fumes are not too bad and usually there is a bit of a breeze.
I could post them at 640 that's no problem I read on here that some have pics off to load faster and was trying to find a happy medium.

vtsteam:
The zinc flame usually looks white to me -- maybe a little greenish, with definite voluminous white smoke. Keeping air out of the crucible with a clay cover can help, and pouring at the lowest temp reasonable that will fill the mold. I notice many people overheat aluminum in videos I've seen, and skim too much, so get a lot of oxidation. I imagine the same is true of brass.

In a charcoal furnace embers inevitably fall into the melt and float on top. This actually reduces oxidation as the burning carbon absorbs it. That, and the usually reducing atmosphere of a pile of charcoal means the aluminum doesn't burn. I don't skim the embers off until pouring. and I get little real dross and shiny castings. I think propane is more convenient to most people, but the tendency with many is to overheat and oxidize the melt with that powerful flame.

I've done a few small brass melts with charcoal, and they worked out well, though fuel has to be added during the melt. I don't know how that compares with a propane melt of brass.

mattinker:
The Zinc actually boils at 907°C and a melting point of 460°C it's not burning it's boiling. The melting point of brass is 900 to 940°C, so keep get to melting point and pour, hot molds will help keep the fluidity up longer. I have no experience of casting brass, it's not very attractive!

Regards, Matthew

Navigation

[0] Message Index

[#] Next page

[*] Previous page