3D Printing Overview

Up Plus 2

Prusa

Dimension uPrint

+ Dimension sst1200es

Objet Alaris30

+ Objet30 Prime

Typical Uses

draft parts

basic internal components

draft parts

basic internal components

structural parts

features requiring dissolvable support

highly finished parts

precision parts

specialty materials

Bed Size (W, L, H)

5.3in x 5.5in x 5.5in

6.7in x 6.7in x 6.7in

uPrint: 8in x 6in x 6in

sst1200es: 10in x 10in x 12in

11.57in x 7.55in x 5.85in

Print Materials

ABS or PLA (colored)

ABS or PLA (colored)

ABS (Ivory), Dissolvable Support

Alaris30: White Acrylic-Based Model, Washable Support

Prime: Colored Acrylic-Based, Flexible, Clear, Washable Support

Material Cost

Low

$0.04/g

Low

$0.04/g

Medium

$4.67/in3

High

$0.35/g

Layer Height (Resolution)

0.3mm

0.012in

0.15-0.4mm

0.006-0.016in

0.25mm

0.010in

0.016mm

0.001in

Printing a 1in x 1in x 1in Cube

Up Plus 2

Prusa

Dimension

Objet

Industry Cost

$6

$6

$77

$81

PDL Cost

$0.68

$0.68

$4.01

$14.85

Print Time

48min

37min

34min

2hr 50min

Complex Plastic Shapes

3D printing has quickly become a core technology used in design prototyping, and for good reason. 3D printed parts can be used in design prototypes to simulate plastic parts that would normally be injection molded in consumer products. Prototypers should use 3D printing wisely though, as printing times can be long and materials used can be expensive. As such, 3D printing should only be used in appropriate situations, such as with complex parts that would be difficult to fabricate otherwise, and when material demands match up with what 3D printers can provide. In general, 3D printed parts are used for 2 distinct purposes in design prototypes: internally for structural elements or to provide outer casings or shells with a highly finished look.

Choosing a Printer Type

FDM/FFF: tougher, more structural parts with a worse finish

FDM and FFF are two acronyms that describe the same type of 3D printing process, where heated plastic is extruded like glue out of a glue gun into precise shapes. FDM stands for Fused Deposition Modeling, and is a term coined by the company Stratasys to describe the process used by their Dimension line of printers, whereas FFF, or Fused Filament Fabrication, is commonly used to describe printers by other companies.

These parts can be made of ABS or PLA, and are typically stronger and tougher parts well suited for functional parts that will move, be handled, or experience stresses. These parts can withstand dropping and can normally withstand additional fabrication processes like drilling and cutting after being printed. If a model needs to be both tough and finished looking, these parts typically require additional products in order to have a smooth finish (we typically apply a spot putty/glazing compound to fill in gaps between layers). Some printers have dissolvable support material, but printers without separate support material will use the model material to make support structures, often leading to a worse finish.

Up Plus 2

Prusa

Dimension

PolyJet: brittle but nicely finished, precise parts

PolyJet printing is an advanced form of 3D printing, where resin is jetted from an inkjet head, similar to the process used by inkjet printers. The material is then cured using UV light to create the model. This process allows for very precise, detailed models.

The acrylic-based material used in polyjet parts also sands very easily, making these prints great for models (typically looks-like) that need a nice outer finish. The downside to these parts is that they are brittle, meaning that they are prone to fracturing when stress is applied. The gummy support material is removed with a waterjet, and then parts that need to be finished are typically wet-sanded.

Objet Alaris

More types of 3D Printers

SLA: Stereolithography 3D Printing occurs when a laser light draws a pattern in a resin tank to selectively cure resin into the model. One common example of this type of printer is the Formlabs series, which uses a variety of light sensitive materials.

SLS: Selective Laser Sintering printers typically melt powdered material in a tray to build up 3D printed parts. This technique can be used to make parts out of materials that cannot be used for 3D printing otherwise, such as metals.

Integrating Hardware

3D printing for design prototyping starts to get really exciting when you integrate hardware into your 3D printed parts! It's common to integrate nuts and bolts, bearings, and bushings into designs for connecting components together or making them move relative to one another. Motors can be attached to belts or lead screws to provide motion. Zip ties or adhesives, such as super glue or epoxy, can be used to fix hardware components in place. DIY-style 3D printers are actually a great example of how hardware can be integrated into 3D parts to make a functional machine.

Making Visual Models

3D printed parts can also be used for creating visual models, where the surface finish of the model is intended to create the feeling of a finished product. There are different finishing procedures for different 3D printed parts, depending on the size of the gaps between layers and how the model material responds to sanding.

3D Printing Design Tips

Printing/Layer Direction

Layer direction is an important consideration when designing 3D printed parts. The 3D printed parts are going to be weakest along the direction that is held together by layer adhesion, so pay careful attention to which way a part is printing if the part needs to be structural in any way.

The print orientation will also affect whether the part needs support while printing, and also the print time, as parts with many layers will take longer (a layer has a minimum cooling time before the next layer can be printed, regardless of the size of that layer).

When designing your parts, think carefully about how the part will be oriented to print, and consider breaking parts up that will need to be printed with a large amount of support material, especially for parts with same-material supports like the Up Plus 2 and the Prusa.

Adding Fillets

When designing parts to be 3D printed, watch out for parts of the design that will have sharp internal corners. In these situations, it is often helpful to add a fillet feature, which increases the cross-sectional area of the layers, allowing for improved adhesion. This will help prevent separation in the spots where the part is the weakest.