DIY Foundry: Lost foam + Petrobond Casting

Another casting session. This time, I'm trying out a super-easy lost foam technique: bury the foam pattern in Petrobond sand. After ramming, the petrobond should maintain its shape, even as the molten aluminum is vaporizing the foam pattern.

Investment casting typically involves coating the pattern with layers of ceramic slurry, waiting for it to dry, burning out the pattern and finally pouring. This technique allows me to skip most of these steps.

Patterns were drawn in Inkscape, converted to gcode with MeshCAM, built by my homemade CNC foam cutter. Gating and vents were attached by hotglue. My attempts to use was to attach foam gating to foam patterns failed. Hotglue seemed to work pretty well, although I will be experimenting to find a better alternative.

Disclaimer: This is dangerous. If you've worked in a foundry for 25 years, I respect your experience and value your suggestions... but please don't imagine that I am putting myself forward as the picture of safety.. or industry standard practice.

Category:

Howto & Style

Tags:

• address
• pour

[Joe11Blue]

Seriously dude, you should be wearing at least some leather's. I t wouldn't take much molten metal of any kind to take off a foot or an arm.

[amaedesign]

@Joe11Blue

Sweet! I was hoping for some troll action here! There's a nice little thread on one of my other videos where foundry experts proceed to remind me (over and over and...) that my lack of safety gear is unsafe. That was the point of the other video.. they didn't read the description. As a result, I turned it into sort of a parody of their finger wagging.

And yes, I do know the experts are right. =)

Curious though.. how does molten metal "take off" a limb? LOL!

[Joe11Blue]

@amaedesign Human flesh will melt at around 800*F. Human bones literally pop at around 1100*F. Bones will not melt or burn, they pop apart.

I'm not trolling, just advising, as some kid that is unaware of the risk's involved could take your lead and get seriously injured. All it would take is a cold spot in a bad mix from the crucible, or something else ridiculously unexpected.

[amaedesign]

I didn't mean you were trolling - I meant that I was... albeit accidentally. My foundry videos seem to draw comments about safety. Fair enough; I am surely not wearing the proper gear here.

You'd think that it goes without saying that hot metal is dangerous. Then again, I've run into enough people that need it to be said. Maybe I should just re-title my videos "How to die in molten metal." =)

[565Customz]

so....how big of a foam part can i do that with?

[amaedesign]

@565Customz

As big as your equipment allows, I suppose. In my case, I'm limited to 8lbs of molten aluminum at a time. That's how much my crucible will hold.

The foam technique itself probably doesn't have a real limit to how big you can go. Naturally, things get more dangerous as you deal with larger machinery and more hot metal (and fuel).

[skinwehr]

@amaedesign

A few weeks ago I was centrifugal casting bronze. The flask had a blow out (my first among hundreds) and white hot, 2000*F, bronze sprayed all over the shop like a white phosphorus lawn sprinkler- it was really dramatic. I was fine, shielded behind the safety barrier, but afterward I noticed my safety glasses, which were on the bench, had been shot right through like a .22 hit them.

So yes, respect molten metal.

[skinwehr]

@amaedesign Haha... More and more I run into people who either A; are to stupid to be trusted with somewhat dangerous hobbies (anything above coloring books and stamp collecting really) and B; people who are too "safety obsessed" to have any hobbies at all.. lest they be coloring in a pink and blue padded nursery.

[1220975]

Could you give a detailed video on your pouring shank? That would be helpful

[Joe11Blue]

@amaedesign Oh ok. LOL!

Thanks for video though, and have you done any Investment Casting you wouldn't mind showing?