3D Printed and Slipcast Cup

In this project, you will learn how to design a vessel in PotterDraw and export a digital 3D model of the form you designed. You will then take that digital model, scale it and make any necessary adjustments using TinkerCad. You will use Cura to prepare the model for 3D model and export your model into gcode. With the gcode file you will 3D print your model in PLA plastic. 

Once you have the plastic 3D print of your digital model, you will learn how to make a plaster cast of that object so that you can slip cast it in multiples using porcelain or another slip casting clay.

What you will learn:
– How to create unique vessels in PotterDraw.
– How to export your model from PotterDraw and import into Tinkercad.
– How to edit your model in Tinkercad to make it easier to 3D print.
– How to slice your model in Cura to create a gcode file.
– How to make a plaster mold from a 3D print.
– How to cast porcelain cups from your plaster mold.

The following tutorial demonstrates how to create digital vessels in PotterDraw. You can download PotterDraw HERE

Once you have completed your model in PotterDraw. Save it as a PotterDraw file in case you want to come back to it and do more editing. Then save export it as an .STL file. This will allow you to open it in other software, including Tinkercad and Cura.

Use the following video to learn how to use Tinkercad to make alterations to your model to make it easier to cast in plaster. This includes making a casting flange with holes to allow you to more easily remove it from the plaster mold.

Now that you have the digital model completed, you’ll need to use a slicing software like Cura to generate the .gcode that the 3D printer will actually read during the 3D printing process.

After you print your model, you’re ready to prepare it for the plaster molding part of the process. The most important part of making a plaster mold is preparation – you need to use a mold soap to allow the plaster to release from the model, as well as taking extensive precautions to make sure plaster doesn’t flow out of the bottom of your cast. Here’s are some step-by-step photographs that will help you walk through the process:

Sanding the 3D print
You may find that you need to sand the 3D print if there are burs or print layers that you want to minimize.
Painting the 3D print
Once you sand the object, you can spray paint and use spray polyurethane or lacquer to make the object smoother.
Using metal flashing for molds
These are three 3D prints with printing casting flanges, each with their respective metal flashing tubes to hold the plaster.
Soaping and prepping the mold
Here you can see inside the mold before the plaster is poured in. The 3D print has already had Murphy Oil soap on it, and you can also see the oil soap on the flashing. Also notice the marker lines indicating where to stop pouring plaster.
Adding plasticine around the base of the mold
It is very important to make sure you don’t have any plaster seeping out of the bottom of the mold. Use plasticine or clay to seal all areas where you think you could have plaster seep through.
Plaster mold after pouring
This is after the plaster is poured and the flashing is removed. At this point, you would remove the plasticine or clay and carefully remove the print from the plaster. If it feels stuck, don’t force it. Use compressed air to blow air between the two parts.

Once you are absolutely sure you are ready to pour plaster, use the plaster calculator on Glazy here: https://plaster.glazy.org/ First you need to calculate the volume, then once you have the volume you can determine exactly how much water and plaster to weigh out.

The following video walks you through the slip casting process, including filling the mold, pouring it out, removing the vessel from the mold and cleaning the rim.

It’s important to clean the rim at just the right time. You want to catch it at just before leatherhard.
When the object has pulled away from the mold around the rim, it’s usually ready to be removed from the mold
Cast cups
Cast cups in progress!

Some fired examples of the cast cups in the tutorials above …