Week06

3D Scanning and Printing

Group assignment

• Test the design rules for your printer(s).

• Document your work and explain what are the limits of your printer(s) (in a group or individually)

3D Scanning and Printing

This week’s objectives:

• Test the design rules for your printer(s) 3D printer : Ultimaker 2+ extended. Material : PLA.

1. Clearance test.

2. Bridging test.

3. Infill test.

4. Finishing test.

5. Overhang test.

6. Angle test.

Individual assignment:

• Design and 3D print an object (small, few cm3, limited by printer time) that could not be easily made subtractively.

• 3D scan an object, try to prepare it for printing (and optionally print it)

3D Printing:

Rhino6 :

1-Started setting my design parameters.

2-Then started sketching my model.

3-Finishing the sketch

Machining:

I. Cura 4.4:

1- Opened the saved “.stl file” with Cura 4.4

2- Selected the type and model of the printer in my lab (Ultimaker 2+).

3- Selected the kind of filament I was going to be using (PLA)..

4- Clicked on slice, previewed the item and the estimated time. Finally I saved the file to the Printer’s USB flash drive.

II. Printing:

1- Connected the USB to the Ultimaker 2+

2- Chose Print.

3- Selected my file

4- Let the printer prepare the file, heat up and do its work.

5- Make sure to monitor the printer every now and then to make sure nothing went wrong.

3D printing process

Modeling

3D printable models may be created with a computer-aided design (CAD) package, via a 3D scanner, or by a plain digital camera and photogrammetry software. 3D printed models created with CAD result in reduced errors and can be corrected before printing, allowing verification in the design of the object before it is printed. The manual modeling process of preparing geometric data for 3D computer graphics is similar to plastic arts such as sculpting. 3D scanning is a process of collecting digital data on the shape and appearance of a real object, creating a digital model based on it.

CAD models can be saved in the stereolithography file format (STL), a de facto CAD file format for additive manufacturing that stores data based on triangulations of the surface of CAD models. STL is not tailored for additive manufacturing because it generates large file sizes of topology optimized parts and lattice structures due to the large number of surfaces involved. A newer CAD file format, the Additive Manufacturing File format (AMF) was introduced in 2011 to solve this problem. It stores information using curved triangulations.

Printing

Before printing a 3D model from an STL file, it must first be examined for errors. Most CAD applications produce errors in output STL files, of the following types:

1. holes;

2. faces normals;

3. self-intersections;

4. noise shells

5. manifold errors.

Finishing

Though the printer-produced resolution is sufficient for many applications, greater accuracy can be achieved by printing a slightly oversized version of the desired object in standard resolution and then removing material using a higher-resolution subtractive process. The layered structure of all Additive Manufacturing processes leads inevitably to a strain-stepping effect on part surfaces which are curved or tilted in respect to the building platform. The effects strongly depend on the orientation of a part surface inside the building process.

Some printable polymers such as ABS, allow the surface finish to be smoothed and improved using chemical vapor processes based on acetone or similar solvents. Some additive manufacturing techniques are capable of using multiple materials in the course of constructing parts. These techniques are able to print in multiple colors and color combinations simultaneously, and would not necessarily require painting. Some printing techniques require internal supports to be built for overhanging features during construction. These supports must be mechanically removed or dissolved upon completion of the print.

All of the commercialized metal 3D printers involve cutting the metal component off the metal substrate after deposition. A new process for the GMAW 3D printing allows for substrate surface modifications to remove aluminum[51] or steel.

Materials

Traditionally, 3D Printing focused on polymers for printing, due to the ease of manufacturing and handling polymeric materials. However, the method has rapidly evolved to not only print various polymers] but also metals and ceramics, making 3D printing a versatile option for manufacturing.