概述:

This documents describes the applicable design rules for the Full Color 3D printing process on Shapeways.

Process overview for full color 3D printing

Wall thickness rules and guidelines

Structural strength rules

Clearances rules

Full color 3D printing, the limitations

Design recommendations

Full color 3D printing process overview:

The Full Color Sandstone material and the Full Color 3D printing process on Shapeways uses Zcorp 650 3D printers. The 650 is a significant improvement over previous Zcorp machines since it enables 3D printing using the color black and eliminates some of the “blurring” issues associated by other Zcorp printers. The process however that we use is different from regular printing using these machines.

The process itself works by a printing head incredibly similar to a inkjet printing head depositing a powdered plaster material and also adding color to the print. The material used is a powdered plaster. Traditional issues with the Zcorp process are flaking, lack of structural strength and a 'washed out' look.

To combat this lack of strength Shapeways uses a rapid thermoset composites. These add significant strength to the 3D printed parts as compared to traditional Zcorp finishing techniques such as infusion with cyanoacrylate (Super Glue). Additionally a unique machine is also used to apply the composite materials using a resin infusion method. Compared to traditional Zcorp parts the Shapeways Full Color 3D printed models and parts will be stronger and have brighter clearer colors.

For more information about the file requirements for the process you can look here.

Wall thickness rules:

The minimum wall thickness is 3mm Features will print up to 0.1mm. Please see wall thickness tutorial for more information.

Sharp surfaces have additional problem under the Full Color 3D printing process. During cleaning the tips of the sharp surface (aka spikes) can be brushed off very easily. These points will expose white tips at these sharp surfaces which damage the overall look of the part. This means that small details that break will look really ugly. Please refrain from using small pins, spikes or very thin breakable details in your Full Color models.

Structural strength rules:

Full color 3D printed models are very brittle when they are printed but not yet cured. The structural strength of the model is very important. The production staff need to be able to handle the model manually in order to remove it from the printer, remove support material and put it in the resin infusion machine.

The following example shows a model which has structural strength issues:

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The legs and neck are too thin to sustain the weight of th body and head respectively. When printed the model will collapse into itself. The right arm is too thin to sustain the weight of the gun. The tail should also break if we tried to print it. This is a good example of a great model that should print well in White, Strong & Flexible or the Detail materials but will not be printable in Full Color. Please remember how fragile these models are before they are infused.

To insure a model can be properly printed , handled and shipped we apply a body volume vs limp thickness ratio. Please do not make jokes about this unfortunate internal technical term. This ratio is 1.5. For example if a head has a volume of 12cm3 the neck should be at least 9mm thick to be able to support the head.

Full color 3D printing, the limitations

Parts in parts or intertwined parts are not possible in general. They require extensive manual labor and have high risk of failing our quality requirements.

These parts cannot be cleaned properly. Each part of a model needs to be reached with a brush to effectively clean it properly.

Moving parts are not possible. They require extensive manual labor and have high risk of failing our quality requirements.During curing these parts get fused together. To avoid this the part needs to moved constantly during the curing process.

Similar to parts in parts or intertwined parts also deep or narrow valleys are not accepted. Powder gets stuck in these valleys because the brush cannot reach it.

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Recommendation is to make valleys have an angle of more than 10º.

For small or delicate parts we would recommend another process.

The resolution of this process is lower than the others so for high definition needs we would also recommend White, Strong & Flexible or the Detail processes.

Even though these models will be stronger than any other models made with Zcorp machines the grey Robust and White, Strong & Flexible processes provide you with much more strength.

Main advantages for designers:

The process is our cheapest material so it should make it easier to make larger things.

The build volume is large so this helps also.

So with regards to pushing the envelope in technical models, moving models etc. we would not suggest the Full Color3D process. We expect people to have the most success with characters, interior decoration items, sculpture, personalized sculpture and co-creation items that capitalize on the fact that people can upload their own textures, patters or images to the Co-Creator.

Design recommendations:

The following recommendation enable designers to solve most of the process related design problems:

Ensure that the models can stand upright at all times

Ensure more than enough structural strength of legs (thus holding a bigger body volume – limp thickness ratio)

Small / thin features like hands & fingers should be closed and attached to the main body.

Tails of animals or similar model parts should rest on a plate

Rigid body or strong backbone improves the structural strength of a model- For example: support an animal with thin legs with a thick tail (like a squirrel) or a thick pillar right beneath the body.