Let's start up a Metal Casting conspiracy


(Lady Red) #1

A few folks have been discussing doing metal casting in the kiln/sparkleforge, so let’s start conspiring here.

I just bought a big roll of 3d printing filament that is supposed to be able to be burned out in the kiln. That would let us 3d print parts and cast them in metal. I’ve also been doing a decent amount of work with wax sculpturally so I can talk about that process too.

I’m currently taking a metal casting class at CCSF.

I also have some cuttlefish so we could do some cuttlefish casting to get more experience with casting in general. That’s a really fast and easy way to get started.

So who else is interested in joining our casting conspiracy?


#2

I took a foundry class at the Crucible a few years ago, it was pretty fun and I got a few doorstops out of it. I have been idly wondering how much of an OSHA nightmare it would be to cast type but that’s probably out of scope for anything at NB given the Pb


(Lady Red) #3

what’s Type?


(Trent) #4

This would be great. I would be so glad if the hot area got used and I have a few things I would like to try since others are interested.


(Tyler Maran) #5

We also have a huge block of wax that could be used for some lost wax casting. I say we put together a few molds (printed and wax) and we can burn them out in the kiln. Best to do it with several molds so we are making best use of the kiln time.


#6

Metal type, like fonts for letterpressing. Used to be made entirely out of lead but now made from some kind of antimony alloy I think. Pretty sure there’s still a bunch of lead involved though, so probably not practical to do here


(Lady Red) #7

@robbintt speaking of other things to try, I wanna make bismuth crystals!

Also I’m pretty familiar with shaping hard and soft wax by hand. Soft wax is kinda like modeling clay, hard wax is kinda like plaster carving.

I have a bunch of cuttlefish to do cuttlefish casting as a quick way to get started. The cuttlefish is a very soft, foamy material that’s pretty fire resistant - you can carve a small (approximately 1-2 inch) flat mold into it and pour the metal. I think that would be a great way to get started and learning the process of casting. doing a lost wax burnout takes a longer attention span because it takes several days

Should we choose a day to meet up and work on this stuff?


(Trent) #8

Yes! I am in. How is this weekend? Will we need multiple days to cast and pour or can we do it in 1 day? (Based on your class?)

···

On Fri, Apr 5, 2019 at 9:40 AM Lady Red via Noisebridge noreply@discuss.noisebridge.info wrote:

mcscope

      [Lady Red](https://discuss.noisebridge.info/u/mcscope)

      Laser Trainer




    April 5

@robbintt speaking of other things to try, I wanna make bismuth crystals!

Also I’m pretty familiar with shaping hard and soft wax by hand. Soft wax is kinda like modeling clay, hard wax is kinda like plaster carving.

I have a bunch of cuttlefish to do cuttlefish casting as a quick way to get started. The cuttlefish is a very soft, foamy material that’s pretty fire resistant - you can carve a small (approximately 1-2 inch) flat mold into it and pour the metal. I think that would be a great way to get started and learning the process of casting. doing a lost wax burnout takes a longer attention span because it takes several days

Should we choose a day to meet up and work on this stuff?


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(Lady Red) #9

I could do saturday (tomorrow)! I can bring the cuttlefish and I’ll see if I have any metal I can bring.

According to the way my class has gone, if we make cuttlefish molds we ought to be able to make the molds and cast the same day. Wax is more involved and seems inevitably multiple days (or i guess one really long day may be possible)

We’re probably gonna have to figure out how we can do it ourselves since we have different equipment, but I’ll explain how my class.

Typically here’s how my class goes.

Students prepare wax at home. We use either hard wax (carving process) or soft wax (modelling/additative process. I prefer this). Hard wax is good for geometric shapes and gives you more control, soft wax is good for more organic shapes and is difficult to get clean lines and edges. We buy the hard wax from Otto Frei in oakland and I believe the soft wax is from riogrande.com. Soft wax is also called microcrystalline - they may have it in douglas sturgess. There’s also red INJECTION WAX which you can squirt into silicone molds with a special machine, but I haven’t used it yet.

in class, they add sprues, WEIGHT IT, and stick it into a metal flask, then invest it (with an investment material that is Not Plaster but is plaster-y. I know it contains fiberglass. We use a vacuum hood to get the bubbles out of the investment before it starts to set.
Then we wait 1 hour to set and stick it in a machine called a Steam Dewaxer which burns the wax out of the flask overnight.

So that’s a hard time limit - 1 hour to set the plaster and then begin the burnout, which we give overnight. We would probably have to see how long this takes us to do in our kiln, but I think we ought to expect multiple hours.

We come back two days later and the instructor has moved our flasks from the steam dewaxer into the kiln so they’re really hot. We heat up our metal by placing it on top of the kiln - (putting cold metal into a hot crucible is bad in some way that I didn’t catch). Once the metal is warm, we put it into the crucible in a centrifugal casting machine.

Here’s an image. Ours looks like this. It’s in a big metal drum which keeps any metal from escaping.

This is like a centrifuge with a crucible and spot for a flask on one side, and a counterweight on the other, with a spring that you can wind on bottom. The crucible has a little mouth on the side that pours into the flask

It’s surrounded by a tall metal wall to prevent molten metal from flying everywhere if it doesn’t go into the flask

We make sure the screws are tight and wide the centrifugal machine, then hit the metal with a compressed natural gas (CNG) + o2 torch long enough to melt the entire thing.

When it’s halfway melted, we take the flask out of the kiln and place it in the centrifuge. We finish heating the metal and let the centrifuge go. When it spins the lake of liquid metal goes up the wall of the crucible and out of the mouth of the crucible into the flask.

We wait for it to cool off slightly and remove it with tongs from the centrifuge. Let it sit a bit more then quench it in a bucket of water. Then you fish the casting out of the water and start cleaning it up with a flex-shaft machine - which is like a giant desk mounted dremel for metalworking.

So I think we ought to try to make some cuttlefish molds when we meet up and try to do some test pours to figure out how our systems works, and maybe start some prints or investments. I have some wax so if we want to try to do a burnout in the kiln maybe we could


(Tyler Maran) #10

I think some cuttlefish pours would be fun and easy for a practice run. That’s something we could knock out in a day.

I’m not sure what kind of plaster you are using in your class, but it typically takes more than a few hours to dry (or else it would crack in the kiln burnout process). I’d say once we get the tools ready, it’ll go something like this:

  • Make our wax molds
  • Make our initial investment (day 1) with plaster and a vacuum chamber (we have a small one at NB). Leave the plaster to dry for a day.
  • Do a burnout in the Kiln (day 2). I would recommend not overnight, because I would like to supervise it (smoke and ventilation and what not). This will take 3-4 hours and the machine shop will probably just be off limits. I imagine hot and smelly. Between burning and cooling, this will probably be a full day.
  • Pouring (day 3): we will need to collect some metal (brass, aluminum, pewter are ideal) for our casting. Our crucible and foundry here will probably hold about one mold at a time.

(Trent) #11

The burnouts in the past were totally fine, totally safe, and not smelly. It didn’t cause too much heat in the room either with the forge exhaust hood flipped on.


(Tyler Maran) #12

Hold up. We should cast the NoiseBridge Logo out of Club Matte bottle caps.


(Lady Red) #13

Moldlay castable 3d printing filament just arrived. Should we meet today to hack on this? I’ll bring the cuttlefish and some bronze. I’ll head over there around 2pm


(Tyler Maran) #14

Yea I’ll be there in an hour or so.


(Lady Red) #15

I’m here working on getting a print started with Moldlay. Come find me!


(Lady Red) #16

So current state:

  • There’s moldlay in the 3d printing area, attached to one of the printers. I labeled the side with tape. I tried a print but it fell off the printbed after 2 hours and so I had to abort it… then I couldn’t get any more filament to come out of the printhead after that. The moldlay is pretty soft and if the filament isn’t feeding smoothly, it tends to get stripped by the feeding wheel and bunch up. I did manage to get most of a print done though so it seems promising.

  • I made a cuttlefish mold and left a bag of cuttlefish and a screen to sand them in a brown paper bag underneath the metal table. Feel free to grab one and make a cuttlefish mold if you know how, or catch me or Tyler in the space and we can show you.

We should make some molds and meet up to do some pours. Feel free to use the moldlay or cuttlefish to make 'em


(Lady Red) #17

Here’s a good video on the casting process, for anyone catching up. This one shows some extra steps you can do to get a hollow metal casting. We’re gonna do simpler stuff, at least to start


(Trent) #18

I have been hiding under a rock. Are you around NB today?


(Lady Red) #19

Today I’m at an all-day filming of Joseph’s technicolor dreamcoat for my spouses birthday. The 3d printing filament is at noisebridge though if you wanna play with it


(Jarrod) #20

This sounds completely rad.