Beste practices for 3d Clay printing.

How to properly operate your 3D Clay printer

In general the information provided in this section is applicable for all VormVrij® branded 3D Clay printers. If there is a very different approach for a specific model, it will be highlighted in the provided answers.

Is it difficult to 3d print with Clay?

No, and yes.
It’s as difficult as you make it.
Printing with clay is different compared to 3d plastic printing. In most cases you have to mix your own print medium and prepare your own clay cartridges to feed the printer.

On the other hand, once you have the clay, printing is quite straight forward. Simple designs, like basic tube shaped objects, are super simple to create.
With every new printer you receive one filled clay tube and an SD card with example G-codes. You can make your first prints right after installing your LUTUM® 3d Clay printer.

Can I use grogged clay, and what is best practice?

The new stainless steel augers [1] allow to print with grogged paste (0.2mm grogg at 25% mix).
There are some advantages to print with chamotte.

  • You need less water to get the correct clay viscosity
  • The prints are stronger
  • The final objects shrink less in the kiln

But there is a catch, use this clay improperly and the auger screw will wear to the point it needs replacement. [2] This is an expensive part so best follow the guidelines below.

With grogged clay you need to make sure there are no blockages in the clay flow. If there are, you need to solve the blockage, do not increase pressure or flow.

If there is a blockage at the tip, for example a build up of firmer clay than what’s in the cartridge;

this happens when the rotation speed of the auger is higher than the actual displacement/extrusion speed of the clay.

It will start to separate particles and water, water goes up, clay goes down and becomes more difficult to extrude.

To fix this you can increase the flow for more pressure. This is not the correct way, the auger will start to wear[3] as it grinds along the chamotte particles in the clay. Especially in the upper part where new clay is fed.

Eventually the soft slurry will move down and more of the screw can rotate while chamotte just hangs around.[4]

Over time it becomes worse as the only way to print is rotating the auger faster to debind the clay and push it out.

To solve this properly, as soon as you see that the extrusion speeds start to change during a print while the speed and flow of the machine remains the same:

  1. increase the pressure.
  2. clean the nozzle assembly up until the screw.
  3. before re-attaching the nozzle assembly extrude clay to refill the extruder with new homogenous clay.
  4. the rotation speed of the auger at moderate speed of 50mm/s with a 3mm nozzle should be around once every second.

You can print chamotte without wearing the auger significantly. Make sure the auger is not mixing, just pushing your clay down.