Printing with MOLDLAY

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pyronaught
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Re: Printing with MOLDLAY

Post by pyronaught » Sat May 21, 2016 2:01 am

The parts are small enough to fit that, and that was the process I planned to use since it looks like air bubbles are the number one enemy. There's a video showing a guy making lost PLA castings for jimc here that looks like a good process to try and follow:

https://www.youtube.com/watch?v=20iYekoQUUA

I built a nice vacuum pump a few years ago for doing vacuum bagging that should work, I just need to get one of those glass domes and whatever those perforated brass casings are called.

This guy has a good video on making a simple forced air charcoal foundry and is getting pretty good results with casting aluminum with it:

https://www.youtube.com/watch?annotatio ... SoWxG30rb0

I wouldn't put the foundry pot on that wobbly flower stand like he is doing though, that's an accident waiting to happen.
Experience is what you get when you didn't get what you wanted.

Mach
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Re: Printing with MOLDLAY

Post by Mach » Sat May 21, 2016 6:15 am

Yeah that video is DavidF - he's a mod over at Alloy Avenue. The vacuum table is one part that is used for the investment process. The acrylic domes you can get from a jewelry supply house like rio grande. The part you're referring to is called a perforated flask. You'll need a vacuum caster to make use of it. It's different than the the vacuum table. It allows you to pour metal while pulling a vacuum on the invested flask. You'll also need a kiln or burnout oven to burn out the PLA. And lastly, you'll need a furnace to melt metal.

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pyronaught
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Re: Printing with MOLDLAY

Post by pyronaught » Mon May 30, 2016 5:22 am

Been reading a lot and got my first furnace built.
furnace1.jpg
furnace2.jpg
Experience is what you get when you didn't get what you wanted.

Mach
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Re: Printing with MOLDLAY

Post by Mach » Mon May 30, 2016 6:11 am

Looks good! Did you DIY refractory or buy commercial?

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pyronaught
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Re: Printing with MOLDLAY

Post by pyronaught » Wed Jun 01, 2016 4:33 am

Mach wrote:Looks good! Did you DIY refractory or buy commercial?
I did DIY plaster of paris and playsand 50/50. I made some mistakes though so I'll be surprised if this doesn't crack. If it does, I plan to use commercial refractory for the next one. It's going to take a few weeks to dry this thing out though, it is really a lot thicker walled than it needs to be. Next time I'll put a drain hole in the bottom, use a fiber blanket around the perimeter, make the cavity larger to reduce the amount of refractory used and cast the thing in one pour instead of several. Plaster of paris just sets to fast to allow doing a single pour on something that large. Even with the 10 quart batches I was mixing it was still on the verge of setting by the time I was done mixing it, so I know there are air voids inside of it.
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pyronaught
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Re: Printing with MOLDLAY

Post by pyronaught » Wed Jun 01, 2016 4:47 am

From what I've been watching on youtube, it really looks like sand casting is the way to go compared with lost PLA. With sand casting you can print your part with whatever filalment you want, then coat it with something to smooth out the surface and not worry about if it will burn out or not. Plus you get to keep reusing your printed part instead of destroying it each time. I like that you can also inspect the interior of your mold before using it too, and redo it if there is a flaw instead of finding out only after you have gone through all the trouble to cast it. You also don't have the burn-out step, nor do you need a vacuum chamber and you can keep reusing the same sand for a long time. It's just a lot simpler and you get great results with less surface flaws as long as you are using a nice fine greensand for it. The geometry of your part has to be compatible with sand casting of course, but I think a lot of parts would work with it.

Here's a good video showing some sand casting: https://www.youtube.com/watch?v=4DwuSpmhMKs

That guy has a lot of great casting videos, including a complete how-to series on how to build that awesome beer keg furnace he has. If I can get a keg I'd like to make one just like it.
Experience is what you get when you didn't get what you wanted.

Mach
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Re: Printing with MOLDLAY

Post by Mach » Wed Jun 01, 2016 11:57 am

Check out myfordboy's furnace build. Very well done. https://m.youtube.com/watch?v=HFaA218gT2k

Brian's keg furnace is top notch but a little too big and heavy for my current needs. I'm currently building my furnace from a couple of propane cylinders. I'm printing the hot face mold in pieces with the idea to cast in commercial refractory and burn off the mold while firing the hot face. That'll get wrapped if firebrick or ceramic wool.

I've done sand casting before. It can work well for the right parts. It takes a moderate amount of patience for complex parts as the steps involved can trash your mold at any point. But like you said, you can start over with no net loss.

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pyronaught
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Re: Printing with MOLDLAY

Post by pyronaught » Fri Jun 03, 2016 2:06 am

That's an interesting method, you wouldn't be limited to the size of whatever metal container you could find doing it that way. Using the sander to make a vibrating tamping stick was a pretty good idea too.

I've got parts coming for building a Ron Reil propane burner. I decided to skip using charcoal due to the mess and lack of temp control.

One thing I don't see hardly anywhere are tongs for extracting and pouring. I did see some on budget casting.com, but they were very expensive. Maybe everyone just makes their own so there is no market for mass produced tongs. The combination extraction/pouring tongs the Fire Keg guy has looks pretty awesome, but I've never seen anything like it for sale anywhere. I bet it was expensive.
Experience is what you get when you didn't get what you wanted.

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pyronaught
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Re: Printing with MOLDLAY

Post by pyronaught » Mon Jun 06, 2016 4:29 am

While waiting for the parts to get here for my Reil burner, I decided to design my own that could be made from cheaper parts that you can buy locally. The burner below can be made from $22 worth of parts from places Lowes or Home Depot. The regulator and braided hose I bought on Amazon, so that is not included in the price. That's a 40 psi regulator with a nice metal pressure adjustment knob that works really well. The pipe I'm using is 1/2" size, so the whole thing is pretty compact and would work well in smaller furnaces. The flame output is not small though, as you can see in the image, so it could also be used in larger furnaces. The venturi on the inside is a 1/4" compression cap, so it allows changing the cap to play with different hole diameters and the hole is perfectly centered so that you don't have to play around with trying to center it like you do those side mounted Reil burners.
burner1.jpg
burner2.jpg
Experience is what you get when you didn't get what you wanted.

Mach
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Re: Printing with MOLDLAY

Post by Mach » Mon Jun 06, 2016 3:07 pm

On the tongs, you can buy them from budget casting supply or similar but they can get spendy. Brian's tongs are very cool. Looks like he designed them in a CAD package and had them fab'd in stainless. MyFordBoy has a nice combo set as well albeit lighter weight.

Nice work on the burner. I have a natural gas line already for a 300Kbtu crawfish burner so I went the natural gas route. That's 2" exhaust pipe plumbed into a 3/4" line.

Image

Here's my furnace design. A majority of the hot face forms are 3D printed.
Image

And just so we're on topic. Here's the casting flask insert that I'm printing with Moldlay. It drops in the bottom of the casting flask when investing. Once burnt out, the resultant channels assist in vacuuming a non-perforated flask.

Image

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