Ceramics Design Rules: Basic Info
|Min Wall Thickness
However, to keep your models from breaking, we recommend:
- If sum of bounding box dimensions (x+y+z) is between 120-200mm, min wall should be 3mm
- If sum is between 200-300mm, min wall should be 4mm
- If sum is between 300-400mm, min wall should be 6mm
|Max Wall Thickness
||for embossed details: keep width of detail greater than 2mm, or 36pt font (Arial)
for engraved text: keep width of detail greater than 3mm, or 60pt font (Arial)
|Min Hole for Hollow Parts**
||10 mm in diameter, though if possible try to make it 15mm
Other holes should be greater than 3 mm
|Min Size (bounding box)
||Dimensions of the bounding box must add up to 120 mm or greater
|Max Size (bounding box)*
||300 mm x 220 mm x 170 mm AND
the sides of the dimension should add up to no more than 400mm
|Minimum Density of Model
||Material to Bounding Box Ratio should be greater than 5%
||accurate up to 3% deviation
|Multiple Parts per STL
||See below on how to fit multiple parts into one STL
||Clearance should be min 3.5mm
Pieces that fit together are suggested to have clearance of 4 mm (ie teapot & lid).
Objects must have a clear base
* Special orders up to 200 x 250 x 200 can be considered but will depend on design, fill percent and whether supports are needed.
** Designs that are hollowed out should have a hole so that the printing powder can get out of the design.
*** Clearance is distance between parts--like for instance the distance between tips of a tweezer--required to maintain the gap
Tips on how to create stronger structures
The following will help you increase your chances of your design being strong enough to survive the printing process. This is not to say that if you follow this design, you will create an infallible model. Nor is it to say that you can't create models unless you follow these tips.
Tip #1: Rule of Thumb: If this structure was made of wet sand, would it break?
Just like Stainless Steel, there's a part in the process of making ceramics model where the model is fragile and brittle. It's basically like wet sand. So when building your structures, think--can my structure be made with wet sand?
Tip #2: Hard to reach places might not have glaze applied. Glazing will reduce definition of design details, for example grooves will fill with glaze. up to 1 mm of glaze can be added in certain areas.
Tip #3: When putting multiple parts in one file (ie cup and a lid), please keep in mind the following
Parts should not be nested
The longest dimension of all parts must be on the same plane
Individual parts in an STL should have bounding box where the dimensions add up to above 12cm, or 120mm.
Tip #4: Try avoiding structures that change from thick walls to thin walls repeatedly
Tip #5: Joining faces should have a radius of 2.0 mm
A rule of thumb is can you snugly fit a 4mm (diamter) ball bearing into the corner of your piece? If there's a gap between the corner and the ball bearing, then it is too sharp. Sharp corners are likely to crack when heated.
Tip #6: Thin struts cannot be attached to a large unsupported sections. Unsupported struts should be less than 8 mm in length.
Tip #7: Large sections should be lower in the model to add stability
|Stronger structure because the foundation adds weight to the bottom
||Weaker structure because the head is heavy
Tip #8: Your model should have a strong and obvious base/bottom
These pieces needs to be glazed. While it's being glazed, or toasting in the oven, it needs a base to support it. Pieces with a clear base will be much more likely to glaze than pieces without. For pieces without a clear base, we have support structures, but the support structures might leave small dents in the surface of the glaze.
|These bunnies have a clear bottom.
||This bowl also has a clear bottom
Pieces without clear bottoms will be put on stilts, think of it as tiny claws that hold up your piece while it is in the kiln. Because the support only touch the object at a small point, it minimizes the disruption in the glazing process. However, the point still creates little "craters" in the glaze surface.
To avoid this, make objects with a clear base
, a clear surface the object rests on.
Tip #9: Holes in pieces must be at least 5mm in diameter. If you only have one escape hole for your hollow part, that hole must be 10mm in diameter.
Holes are difficult because it is difficult to get the powder out. Also, when glazed, smaller holes will seal in the glaze, thus the 10mm minimum.
For decorative holes, please keep the holes above 5mm in diameter. This also applies for things like necklace loops.
Tip #10: Edges should be smooth (no knife edges), or long tapered edges. Try to make your edges dull and rounded.
The jagged edges will fall off during depowdering
Tip #11: Pieces that "fit" together are tough, but if you have to design this please keep a clearance of 4 mm.
For pieces that fit (ie teapot lid and teapot), the clearance between the designs should be 4 mm. This is because the glaze will add up to 1 mm of surface volume in some places. To ensure that your piece still fits, please keep a 4 mm gap between the two pieces.
Also note, items must have a bounding box, where the dimensions add up to at LEAST 120 mm
The pieces can't be small otherwise it will be difficult to glaze. Also, small pieces tend to lose all their details in the glaze process. We decided to do pieces where the bounding box ADDS up to at LEAST 120 mm, so you can still print thinner tiles and more square-ish models.