3D printing

Printing Parameters

Layer Height

Layer height is the thickness of each layer on a print, and is often described as the resolution or print quality. Thinner layer heights will yield higher resolution prints, but will also take more time to complete. Thicker layer heights will yield lower resolution prints, but can save time in printing. For most student projects, somewhere in the middle of your machines capabilities may yield a good balance of print quality an print time.

Infill

3D printing allows us to create semi-hollow objects in order to save time and material. Smaller infill percentages use less material and can save significant time in printing, but will yield prints with lower strength. Larger infill percentages will use more material and take longer to print, but will be stronger, heavier, and more durable. For projects that do not have any strength requirements, 20% infill is a good starting point. For projects that do have some mechanical requirements or are structural in nature, try starting with an infill of 50%.

Raft

A raft is a thick first layer designed to adhere to the build surface and allow models to stick easier. Rafts are sacrificial features in 3D printing and are broken off and discarded once the print is complete. Rafts are particularly useful when printing tall and narrow models or models that do not have a large flat surface to stick to the build surface.

Supports

Printers build components layer by layer, each layer adhering to the layer underneath it. Supports are needed when a feature in a 3D model is floating in air relative to the printer build surface, meaning there is no material underneath it for the new layer to adhere to. Supports are sacrificial features in 3D printing and are broken off and discarded once the print is complete. They enable printing for more complex geometries, but like other additions they add time to the print and use extra material.

Common Failures

Build Surface Adhesion

One of the most common failures seen in 3D printing is poor adhesion to the build surface. If your print knocks loose from the build surface in the middle of the print, the job will continue and will likely produce a jumbled mess of filament. Under certain circumstances, this may cause damage to the machine.

Solutions

1. Design parts with large flat surface for proper build surface adhesion.
2. Use a raft.
3. Make sure model is placed flat on the build surface in slicing software.
4. Clean build surface and reapply adhesive.
5. Perform Z-offset calibration printer

Extrusion Issues

Another issue you may see is filament is struggling to extrude from the nozzle or is blocked entirely. With use nozzles can jam with various forms of build up causing extrusion issues. There also may be issues with the extruder itself causing issues.

Solutions

1. Make sure extruder is pushing filament as expected.
2. Replace nozzle.
3. Clean nozzle.

FDM Printer Parts

Build Surface

No surprise based on the name, the build surface is the surface onto which the 3D model is built. Build surfaces can be a variety of materials based on your brand of printer but are commonly glass or metallic. Some printers have heated build surfaces to help with adhesion of the model to the surface.

Hot End

The heating component used to heat up the nozzle and melt the filament as it extrudes.

Nozzle

The heated component where filament is fed into and comes out of the bottom to build components. Nozzles come in several materials and diameters and is chosen according to desired features on the printed parts.

Sensors

There are several sensors present on FDM 3D printers to monitor printer components and make sure prints are completed successfully. Features will vary by 3D printer brand and model.

1. Temperature sensors
   1. Used to monitor the temperature of the nozzle and build surface (if applicable)
2. Limit switches
   1. X, Y, and Z limit switches
   2. Used to find the position of the extruder and build surface relative to one another
3. Z-probe
   1. Used to measure distance from nozzle to build surface and determine bed levelness

Stepper Motors

Used to control X, Y, Z axes of the 3D printer and to feed filament into the hot end and nozzle.