3D Printing Guide

This is a 3D printing guide for CSCF's 3D printer.

While the documentation on this page is mainly for internal use, others may be able to benefit from it.

Glossary

Warnings

The following warnings are very important for safety reasons and to prevent damage to the 3D printer:

• Only use 99% Isopropyl Alcohol (IPA) to clean the 3D print sheet. Do NOT use other chemicals (especially acetone).
• Only use approved filament and material types. The use of cheap filament or incompatible material types may damage the extruder or hot-end.
• Wait 15 minutes after a print has finished before attempting to remove the printed object from the print sheet. This allows it to cool, allows it to detach easier and will prevent damage on the smooth print sheet (if used).
• Never use a knife or spatula on the print sheet. This will scratch the surface and damage the coating.
• Keep your hands free from the 3D printer during use.
• Wait for the extruder to reach ambient room temperature before handling any part of the extruder.
• Do NOT use g-code sourced from online. G-code generated from a slicing program will be machine specific. A 3D printer will happily run any g-code even if it means destroying itself. The safest way to avoid this is to generate your own g-code.

Dangers

While consumer 3D printers are generally safe and typically marketed for home/education, there are still some dangers present that should be considered.

FDM 3D printers have a heating element in the hot-end and print bed. These heaters are regulated by thermistors (temperature sensors) to ensure that they do not exceed their set temperatures. It is extremely important that FDM printers have thermal runaway protection. Most thermistors present on 3D printers track temperature via resistance on a circuit, this means that if a thermistor is damaged or the cable for the thermistor is cut then the controller may read it as a low temperature due to the open circuit. On 3D printers without thermal runaway protection, this would cause the controller to continuously heat the printer unchecked. This is a fire hazard and can damage the heater, controller and power supply of the 3D printer.

The Prusa i3 MK3S 3D printer used by CSCF has thermal runaway protection for both the print bed and hot-end. If either thermistor reports a temperature too low then the print will immediately be cancelled and the printer will cool down with a "MINTEMP" error. Any further 3D prints will be immediately cancelled until the issue is resolved.

The final dangers to consider are regarding the use of certain materials. In FDM printing, thermoplastic filament is melted which will create fumes. How toxic these fumes are is dependant on the type of material being used. With resin based 3D printers, the resin will give off toxic fumes even when not being used. The resin would also require gloves when handling to prevent contact with skin.

Generally, CSCF will use two types of materials on its FDM 3D printer; PLA and PETG. While PLA is much less harmful than other materials due to it being starch-based, it may still have additives to improve print quality and shouldn't be considered 100% organic. Other materials such as PETG or ABS may give off fumes that smell either unpleasant or cause headaches.

When using an FDM 3D printer, always ensure that the space you are printing in has adequate ventilation.

Approved Printing Materials

Generally, the best 3D print filament to use will be Prusament from Prusa Research. While many other online users may recommend their own preferred brands, I prefer Prusament due to their tight spool winding and 0.02mm (20 micron) guarantee on filament diameter deviance. Prusa Research also publicly lists all of their spool data online in order for users to track the exact properties of each one of their spools purchased. -- Devon Merner - 2020-01-07

The following printing materials are able to be used on CSCF's 3D printer and are high enough quality to prevent damage:

• Prusament PLA/PETG/ASA from Prusa Research - $25-30 USD per 1kg - Link to supplier

Choosing a Material

The most common 3D printer filament materials is PLA and ABS.

Polylactic Acid (PLA) is a "bioplastic" material similar to polypropylene, polyethylene and polystyrene made from biodegradable plant sources such as corn, rice starches or sugar feed. PLA has a much lower melting point than other materials and little to no contraction during print cooling. This makes PLA ideal for detail based prints such as models, figurines or smooth surfaces. PLA is typically used around 180C to 220C and does not require a heated print bed to use (although having a print bed around 60C helps with adhesion). Due to PLA's lower melting point, it is not ideal for use in high temperature environments (such as outdoor or car use).

Acrylonitrile Butadiene Styrene (ABS) is a polymer used in 3D printing with a much higher melting point over PLA. ABS is used in most commercial plastics (e.g Lego bricks). ABS is not recommended for large or detailed prints due to the large amount of contraction that occurs during print cooling. This causes major problems with print layer separation, warping and separation from the print bed. ABS is ideal for high temperature environments or for watertight parts (since ABS can be sealed with an acetone vapor bath to be completely smooth). ABS is typically used around 225C to 260C and absolutely requires a heated bed around 110C. The environment ABS is printed in must be controlled to prevent drafts from rapidly cooling and splitting the print. As such, a heated or controlled build chamber is recommended.

PETG is a Glycol modified version of Polyethylene Terephthalate which is typically used in the manufacturing of water bottles. Its characteristics are very similar to ABS in terms of thermal properties and strengths but without the large amounts of contraction that would occur when the print is cooled. All of the 3D printed parts used on CSCF's Prusa i3 MK3S are printer are PETG. PETG is typically printed around 240C to 250C and requires a heated print bed around 90C.

For internal uses, CSCF in most cases recommends only using PLA or PETG. If you are trying to print something with large amounts of high detail (i.e figurines) then PLA is the best choice. If you are printing something to be durable and functional in most environments then choose PETG (although it may not look as nice).