How to 3D print stacked face shields

Given the large demand for protective visors at this particular moment, I have created a complete profile for the latest version of Cura. I hope that will help lots of people contribute to the battle against Coronavirus. The preset is made for the Ender 3 or similar printers that have a 0.4 nozzle (if you have a 0.6 nozzle you can go even faster). The profile is optimized for PLA filaments.

You will find several files containing 2/8/16/24 face shields stacked one upon another.
The version is the closed one which is the ideal one as it prevents airflow to pass from above.

Contents

How it works

The peculiarity of the project consists in decreasing the printing speed and the flow of all the first layers with the use of the Cura modifiers.
Furthermore, it does not require supports, the space of 0.6 mm from the nozzle to the piece, allows the material to cool and not stick, just like when using raft as support.

All of this was possible by modifying a 3D model to acts as a modifier to change the print settings. I’ve copied the original model and changed the total height to 0.6mm and made that model act as a settings modifier.
Now moving the modifier model on the Z-axis bringing it to -0.3 mm, the settings of only one layer of the original model will be changed, with the addition that the modifier protrudes down by 0.3 mm which also makes it easily selectable.

Once the modifier model has been selected, it is necessary to change the speed settings, setting everything at 20mm / sec and the flow, bringing it back to 100%, these personalized settings will thus be applied only to the first layer of each piece.

Now using the GROUP option it is possible to combine the modifier with the original model. At this point, we can duplicate and stack the grouped models at will, pay attention to position them correctly at Z +0.3 and then group them in subgroups to manage them more easily.

Parameters optimization

Most likely you will have to change the flow and temperature by finding the best parameters for your PLA and your printer.

You can use the TEST model which contains only 2 pieces for testing, the temperature must be increased if the extruder starts to jump, (however, using a lower temperature facilitates the detachment of the piece), if you have extrusion problems, also decrease a little bit the speed. The flow, on the other hand, must be increased if the walls come off, or decreased if you see over-extrusion and you cannot separate the pieces, even here the right balance is needed.

Once the test model is printed correctly, you can use the other model with 24 pieces, where they are stacked in groups (they must be separated with Ungroup) to print as many as you want (if you have problems, disable the Cura option that automatically positions the pieces on the plane).

Separating the printed parts

Use pliers to divide them and then a spatula, but be careful! always use gloves!

Main Settings

Hardware: normal or PRO Ender 3, generic PLA, 0.4mm nozzle
Temperature: 210-225C
Flow: 105-115%
First layer: 100%
Top / Bottom: 100%
Line width: 0.67 mm
Layer height: 0.3mm
Speed:
First layer: 20mm / sec
Other 35 mm / sec (on average)
Jerk: 8
Acceleration: 800
Walls: 3
Top / Bottom: 4
Infill: 15%
Combing: OFF