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meduza

MOLDLAY Filament

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Having some experience in lost wax casting, it would be my suggestion to all who would like to try this, to use actual "investment" in order to make a mold around the 3D print instead of much more harsh, concrete which is a mixture of limestone and binder.

Using actual investment powder--a form of plaster of paris, saves time and money. After you heat to "lose the wax" step, your negative is intact, and will have no "flashing issues" when pouring metal, because there are no seams to allow for molten metal to seep into and require manual removal later.

Next, place investment containing cast piece + mold BOTH into a 5 gallon bucket of water, which will dissolve the investment totally, while cooling your molten piece at the same time. Said bucket has a name in casting circles: Quench Bucket

Water is much cheaper than buying and discarding citric acid saturated with cement.

If you are concerned small metal fragments somehow got into your dissolved away from your cast investment material, there is a wet method for quick harvesting of said metal, and a dry method for separating and harvesting said metal fragments.

Wet Method: run contents of 5-gallon bucket containing dissolved investment through a small gold miner's sluice, and catch the run off for drying and reuse. The metal fragments will lie in the bottom of the sluice due to specific gravity of said metal fragments (if there are any). However, if one is working in gold or silver, one should be concerned with any minute losses, as they do add up to big bucks. US$42 per gram for 24K Au is a significant monetary loss.

Dry method: pour through a homemade or commercial brass mesh sieve.

Allow dissolved investment to settle to the bottom of capture bucket as an undisturbed sediment, usually 24hrs.

Using a piece of flexible tubing as a siphon, remove the clear liquid down to the sediment layer. Allow the investment sediment to dry in ambient air.

Remove, crush dried investment with a pestle of some type in the bucket, then pour out as powder.

Measure out the now dried and pestled, powdered investment to reuse, and mark as Used Investment. Store in airtight container as investment is obviously hygroscopic.

On next molding project, measure out old, pestled-back-into-powder-consistency investment PLUS add a small amount (no more than 25% by weight) of new, unused investment mixed in wtih the old. Mix thoroughly with hands or mechanical means.

Voila-- you have new lost wax investment powder mixture ready for your next lost wax casting project.

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Make your own investment from scratch using equal parts of Plaster of Paris ( aka gypsum plaster...yes the stuff found in sheets of drywall found at the lumber yard) and -200 mesh silica sand. Plaster of Paris alone will not hold up dealing with the temperatures needed to cast PMs (gold and silver at 2000 F/ 1100 C.)

 

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In fact you don't need wax (or wax -like), you can do lost PLA casting too. Of course you may need a slightly higher temperature for PLA to flow as a liquid. There are several YouTube videos on this subject.

 

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True that, however, the offgassing of PLA burnout is something that needs to be taken into consideration, especially if working indoors.

Wax burnout offgassing is bad enough--think birthday candle smudge pot. :shock:

 

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DonMilne: Yes you can do lost PLA casting, but it takes quite some time to completely burn out the PLA, and it is definitely something you do not want to do indoors, this seems like a much easier material to work with.

And yes, i also thought that his concrete method were very rough and unnecessary since a real investment form is much easier to work with.

 

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The Moldlay prints ok. I disabled the retraction because I didn't want the heat to creep up the bowden because of the lower melt temp.

I print a basic ring and the treat the surface with a soldering iron to get this fluid molten surface and bring it to the casting service. I don't want to do the casting myself, they have better equipment to do this more precise and quicker... The casting itself is a vacuum system, so the molten silver comes in all the tiny spaces.

PLA works as well, but the guy told me that the temperature to burn out the pla/moldlay is different. For Moldlay the instructions says 270 degrees, but for pla, they use about 800

degrees to get everything out.

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5a33150ad7149_2015-12-1312_44_49.thumb.jpg.313283999871a77ef1b021f687457552.jpg

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