3D Print Preparation

A Slicer programme allows you to import your .stl files and convert them into printing instruction code - for Claybot or any other 3d printer to follow. Your 3d-model is effectively broken down digitally into slices or cross-sections, based on the settings you choose.  Settings depend upon the output material and your 3d-print machine characteristics.  Amongst other things, your Slicer programme will tell you how much material will be consumed and how long your 3d-object is going to take to print. 

This information is then neatly bundled into a GCode file which contains a stream of digital instructions to direct where, when and what the 3d-print-head and clay extruder will do.

The GCode can be delivered into the printer over a network, or by transferable SD card plugged into the Claybot Control Tablet.

The Claybot Control Tablet also comes pre-installed with a full set of tools to move from 3D .stl model to printed clay object.

Printing your 3D clay object

Claybot’s Control Tablet has an intuitive user interface to help you pull the strings.

Use Object Placement to position your piece. ‘Scale’ if necessary and then ‘Slice’ your object into printable layers.

Set the Primary Extruder speed control between 3 - 4 to achieve a good flow of clay.

Start a sacrificial print to check the clay is being laid down commensurate with your print-head speed. Adjust head speed as necessary on the Manual Control tab of Slicer.

After finding the calibration stops your print is ready to go. GCode from the Slicer program drives the movements of the Claybot motors and extruder print-head.

Fine tuning of your print can be done even while it’s in process. Use the touchscreen to determine key parameters: print-head speed and ceramic flow from the nozzle. Begin with a slow print-speed setting and ramp up (along with increased clay flow) once your continuous print builds past the base layers.

It is also great to experiment with independent, outside influences on your 3d-printed objects. For example, the Claybot sound speaker demonstrates how to impart various effects DURING printing. Unusual print-speeds may give a poor result but just might give something uniquely different.

Post-print sculpting

All Pre- and Post-processing of Claybot objects follow standard clay/ceramic practice. After printing you can still shape and work the clay like any other conventionally produced work. The state of the body evolves as the greenware piece dries prior to placing it in a bisque firing.

As an object air-dries it moves through these states:

• Wet (newly produced) and not workable
• Soft (damp surfaces)
• Medium (inner damp surfaces – leather-hard outside)
• Leather-Hard
• Bone-dry

It is important to remember that just because one section of your piece is in one state does not mean internal or wall intersections are in the same state. The time it takes for drying to occur varies depending on design and environmental conditions. But in low humidity, ambient temperatures 20-30°C, this will take a minimum of 2-4 days and could be as much as 7-10. Depending on your project, you might choose to slow this further by wrapping all or parts of your object in polythene to prevent drying out in advance of adjacent sections.

At various points in the greenware drying cycle it may become judicious to imbue decoration to your object. A summary of the main techniques is provided below.

Subtractive Decoration involves removing clay from the surface of your 3d-printed object. This includes:
Carving – which may be done at any stage from soft to bone-dry. Although carving tends to be most satisfying when the clay is medium to leather-hard, gestural “smeared” effects are best introduced in very soft clay.
Piercing openingsinto a clay object may be preferable to attempting to print and support them in the wet state. Piercing is normally done at medium leather-hard stage with a hole-puncher or razor knife. However, it may also be accomplished at the leather-hard or bone-dry stage with an ordinary drill bit.
Incising usually refers to shallow carved lines or patterns using a dull-pointed dowel, or a dull pencil. Too sharp and you are effectively inviting cracks to form!
Additive Decoration is where clay is added to the existing surface of a clay form. In general, you should score the object surface and slurry all add-ons, except in sprigging. If the add-on itself is soft plastic clay, score and slip/slurry only the attachment point on the main form. If the add-on is leather-hard, score and slurry both surfaces.
Appliqué generally refers to preformed flat pressed or carved clay decorations added onto the surface of a piece.
Sprigging is pressing either small coils and/or balls of clay onto the surface. A thin coat of slip (without scoring) is adequate and is a nice way to introduce coloured contrast.
Modelled decoration includes a variety of methods when clay is added and then smoothed into the surface to create raised ridges, strips and pads. Sculptural manipulation with fingers and hands is then accomplished.

Kiln firing

It would seem illogical to begin this section saying that you do not necessarily need a kiln to get the main benefits from a Claybot. You can 3D print, do post-print modelling and decorate with acrylic paints if your objects do not have to perform function (e.g. food and liquid tolerance). They will however remain very brittle.

If you are ready to uncover the true delights of glaze decoration and make your objects impermeable to water for functional purposes, then kiln firing is an absolute necessity. If you do not have one on-site, then perhaps there is a kiln in your school cluster where you can arrange access?

In firing clay your objects are going to go through several chemical and physical phase changes.

Our section The Beauty of Clay has more details