3D model design guidelines for 3d printing

This  design guidelines is for a 3d modeler that wants to design 3d models for 3d printing.

When we design 3d model for 3d printing or additive manufacturing, we must know there is some restriction. Please read <General 3D printing design rules> to know about the restriction. Even you know the restriction clearly, maybe you still don’t know how to do that when you start design 3d model. FDM/FFF is the most technology used on desktop 3d printers, and this article is a design guidelines for 3d printing using FDM technology.

Many filaments are available for FDM 3d printers, such as ABS, PVA, PLA, HIPSTPU…They have different characteristics, and the 3d printer’s precision is different too. So the restriction may be a little different too.

Note: Because 3d printing technology or additive manufacturing becomes better and better, the design guidelines should be updated as well in the future.

Max. size of 3d model

The build size of 3d printer may be different. When we design 3d model, usually it should be less than the build size. Otherwise, we need to split the 3d model and join them together. For example, 3D printer Anet A8, the build size is 220*220*240mm.Then the 3D model should be less than 220*220*240mm.

Minimum size of 3d model

It is the smallest dimension in which your 3d printer can manufacture. In most cases it is no problem, but if your 3d model is very small, e.g. Smaller than 1*1*1mm, you need to pay attention on that.

Wall thickness

3d design guide-wall thickness

The minimum thickness of wall should be equal to or thicker than the suggested dimension. If the wall is too thin, maybe it will fail when printing, or may break when you remove the object from the printer and clean it. The minimum wall thickness may be different according to your 3d model and printer. For FDM printer, usually the suggested minimum thickness is 0.8mm~1.2mm.

Engraved and Embossed Details

3d printing design guide-Engraved and Embossed Details

FDM technology 3d printer:

For engraved surface details or text, the suggested minimum line thickness is 1mm and depth is 0.3mm: W1>1mm, De>0.3mm;

For embossed surface details or text, the suggested minimum line thickness is 2.5mm and height is 0.5mm: W2>2.5mm, H>0.5mm.

Escape Holes

3d print design guide-escape hole

3D printed object’s price depends on the volume of material. So a hollow model will be cheaper than a solid model. Inside some 3d models, there may be hollow cavities too.3D prints are created layer by layer, and there will be some material inside the “hollow” area, for example, some powder, supporting material, etc. After we take out the object from 3d printer, we need to remove the materials. So there must be holes to allow the materials escape.
Usually we use pressed air to blast the excess powder. In order to do that safely, the escape hole should be minimum 2~4mm in diameter.

If there is only one escape hole, maybe the excess material near the hole cannot be removed. So it is best to have multiple escape holes at different locations.

Space between moving parts

3d print design guide-space between moving parts

When you want to create moving parts such as joints, hinges, you must ensure there is enough space. In mechanical engineering, we call it tolerance. But in 3d printing, we can consider that as space or gap.
For FDM technology 3d printer, we suggest there should be a minimum space of 0.4mm between the moving parts. The more space the better.

Space between parts that will be assembled together

If your 3d model is too big, even bigger than the building size of your 3d printer, or the 3d model is too complex and need much support material, then you can consider to split it to make it print easily. After 3d printing, you can assemble them together or glue them.

In order to do that, we must consider the space between the parts need to assemble. In mechanical engineering, usually we can do that by setting proper tolerance. For 3d printing, there should be a proper space between the parts. For FDM technology printer, it should be at least 0.3mm.

This design guidelines is only for 3d printing.If you create 3d models for CNC machining or injection, it will be different.

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