When to 3D Print
- Complex Geometries
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- Internal geometries
- Organic geometries
- Areas where milling can’t be achieved
- Rapid Prototyping
- Parts needed fast and at a lower cost, as opposed to sending to manufacturing
- Parts that don’t require heavy loads
- CAD Variations
- Testing different models or tolerances
- Scaling for visualization
- Iteration
When to consider methods other than 3DP
- Simple Geometries
- Rods can’t be printed vertically and lose shape when printed horizontally
- Options to purchase rods
- Boxes
- Takes longer than laser cutting
- More expensive than buying project boxes (minimart)
- Plates/Disk
- Takes longer than laser cutting or other subtractive methods
- Cheaper to laser cut
- Rods can’t be printed vertically and lose shape when printed horizontally
- Size
- Restricted to build volume
- Can split the design into parts
- Longer print times = higher risks of failure
- When parts or part features are smaller than printer specifications
- Restricted to build volume
How 3D Printing is different from other fabrication methods
Injection Molding
A common way to manufacture plastic parts with complex features, smooth surface finish, and at low cost (in high volume). 3D printing also offers complex features but produces rougher (sometimes porous) surfaces at low cost in low volume.
Thermoforming
Thermoforming is a good option for making thin-walled hollow parts but requires mold.
Subtractive Process(Laser/Mill)
Often faster or cheaper to cut(subtract) from plastic or other stock to create the desired part.
For example, laser cutting parts with features only in the x, y-axis or milling parts with features in the x,y, and z-axis. Using plastic that is not 3D printed offers a wider variety of plastic options like Delrin and HDPE.
3D Methods
FDM/FFF (VIDEO 2)
Fused Deposition Modeling/Fused Filament Fabrication, a continuous filament of thermoplastic through a heated extruder
SLA (VIDEO 3)
Stereolithography, UV laser-based resin printing. A form of additive manufacturing where a light source, such as a laser or projector, cure a liquid resin into a hardened plastic. The build plate is upside down with a tank of photopolymer resin below and the laser projects through the bottom of the resin tank.
SLS
Selective Laser Sintering, uses a laser to fuse polymer powder
3D Printers @ The Makerspace
FDM/FFF
Ultimaker 3/S3/S5
[-]Hobby level printers
[-]Dual Extruders allow for printing two different materials, such as PLA with PVA support or two different colors of PLA
[-]Heated glass build plate ensures the proper adhesion to prevent movement during a print job
Stratasys F370
[-]Industrial-grade printers quality parts
[-]Dual Extruders allow for printing two different materials, such as ASA and QSR support
[-]Heated chamber to prevent quick cooling of the plastic which results in warping
[-]Material management
Markforged Onyx Pro
[-]Continuous Fiber Reinforcement (CFR) - continuously lays down fiberglass into parts
[-]10x stronger than plastics
Dolomite Fluidic Factory
[-]Allows rapid prototyping of fluidically sealed devices such as microfluidic chips, manifolds, and connectors
[-]Uses material Cyclic Olefin Copolymer (COC) a biocompatible, translucent, and robust polymer
SLA (VIDEO 3)
Form 2/3
[-]Engineering/Medical resins available
[-]Achieves better resolution for detailed parts
[-]Watertight parts due to the continuous bounding of resin
[-]Requires alcohol wash and UV cure
SLS
Fuse 1
[-]Nylon material
[-]No support required
[-]Better material integrity than FDM/FFF
[-]Requires post-processing
[-]Sifting unused powder
Choosing Between 3D Printing Methods
- FDM/FFF
- Best For: Basic proof of concept models and simple prototyping
- Layer + Nozzle
- Layer height is determined by Z-axis
- 0.4mm nozzle diameter
- ⬆️ Layer height → ⬇️ print time
- Hot Extruder/Toothpaste consistency
- Thermoplastic going through a hot extruder
- Plastic comes out in a toothpaste-like consistency and cools off afterward.
- Supported
- Parts with over 45° overhangs should consider support
- Support can be the same material as part material
- Water-soluble material PVA for internal supports or supports that are difficult to remove
- Orientation plays a significant role in support
- Infill
- The internal density of the part
- Default 20%
- Reduce print material and print time by lowering the infill density
- Affects structural integrity of part(s)
- Support Removal
- Remove by hand or pliers
- Dissolve in water if PVA
- Drill out holes
- Sand down supported surfaces
- Orientation
- Better accuracy in x/y axis than the z-axis
- Strength better in x/y axis versus layers in the z-axis
- Minimize support material
- Consider supported surfaces
- Taller parts will require a longer print time, increasing the risk of failure
- Lowest Z height
- If support is a need then material cost may increase
- Consider orientation based on curved surfaces
- Stair stepping
- SLA
- Best For: Functional prototyping, patterns, molds, and tooling
- Layer + Laser
- Resolution is determined by Z-axis but SLA parts have a better surface finish because the laser spots size is significantly smaller than the extruders from our FDM/FFF printers
- Partial Cure
- When printing the laser is only continuously bounding each layer and not doing a full cure of each layer. The part does not have full material properties until a final cure is done.
- When printing the laser is only continuously bounding each layer and not doing a full cure of each layer. The part does not have full material properties until a final cure is done.
- One Material
- Since the materials are liquid resins, only one material can be used at a time
- Requires Support
- Support required for overhangs, spans, and unsupported minima
- Support is required to keep parts in place
- Orientation –
- Preventing overhangs
- Reducing print time by reducing the Z height
- Reduce large cross-sections is the Z-axis
- Tilting flat surfaces
- Consider supported surfaces
- Preventing suctions cups between the part and the tank window
- No infill/solid
- To prevent uncured liquid resin left inside parts, there is no selectable infill and the parts are completely solid
- Can create hollow parts with drain holes for the resin to exit
- Post Processing
- Wash
- We perform a full IPA wash based on the material for optimal properties
- Cure
- We perform a full UV cure based on the material for optimal properties
- Support Removal
- We DO NOT remove any support, the user is responsible for removable
- Wash
CAD to 3D Part
[1] CAD (Solidworks, OnShape, etc.) is where the user designs and edits 3D part geometry. At this stage it is good to consider how part will be fabricated by the 3D printer. [2] STL. Exporting CAD geometry as a stereolithography file (.STL) file type translates the CAD geometry into triangulated surfaces. At this stage some curved geometry can become noticeably faceted in the final part. [3] Slicer. The input of the slicer software is a STL file. The Slicer software allows the users to manipulate perimeters that how printer will print the part. Important parameters to consider are: part orientation, layer height, and infill. [4] Machine Code. The slicer creates instructions that the printer will follow; usually gCode. At this stage the user has no ability to effect the final part. [5] Print time. 3D printing often takes hours or days to complete. Making choices at the CAD stage and the slicer stage can reduce print times. Long print times gives the printer more opportunity to have an issue; reduce print times when possible. At this stage the user has no ability to effect the final part. [6] Post Processing After the part is removed from the printer most parts will require post processing; such as removing support material, or washing and curing.
Choosing Materials
Table of Materials
Materials Guide
Slicing (VIDEO 4 & 5)
- Cura Slicing Sample Part
- Choose Printer Size (UM3, UMS3, UMS5)
- Import STL(s)
- Choose material(s)
- Orient parts for optimal resolution, speed, and cost
- Select support
- Select layer height, default .2 layer height
- Select infill, default 20% infill
- View Preview
Video Coming Soon
- Preform Slicing Sample Part
- Choose Material
- Import STL(s)
- Auto orient*
- Auto-generate support*
- Auto-layout
- Check Printability Status
*Formlabs has optimized the auto slicing for each specific material. Only make minimal changes to the auto slicing.
Video Coming Soon
Assembly
Thread Inserts/Nuts
It is better to incorporate threaded inserts/nuts rather than printing threads.
Snap Fits
A quick and easy way of connecting two 3D printed components using interlocking features.
Tolerances
3D printing has deviations from actual dimensions. Consider tolerances when designing your parts.
Part Modication
It may be required to cut 3D prints, sanding surfaces, and drill out holes.
Finishing Parts
3D prints can to polished and painted to obtain a professional look.
