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Choosing Filaments for First Time 3D Printing

Tom Simon

Moderator
One of the first questions a person new to 3D printing has to sort out is what kind of filament to use. The novice is presented with a large number of choices, all with three-letter-acronyms (TLA’s). The most common filaments are PLA (Poly Lactic Acid), ABS (Acrylonitrile butadiene styrene), PETG (Poly Ethylene Terephthalate, HIPS (High Impact Polystyrene ), Nylon, as well as a number exotics such as Ninja Flex, conductive filament, and others.

In addition, there are many filaments that have additives that change their color or appearance. Typically, these are conventional materials such as ABS or PLA that have pigments or additives mixed in. Some of my favorites have a wood like or metallic appearance. We’ll talk about these a bit later.

The two most common materials are PLA and ABS. If you are just starting out, you will want to use one of these. ABS, however, is the more challenging of the two to use. Because of its chemical properties it shrinks more than PLA as it cools down. As a result, it can be difficult to get ABS to adhere to a print bed that is not heated. It will curl up, causing the print to fail. The solution is to use a heated print bed, typically maintained at around 110 C.

With ABS it is advisable to keep the entire work piece warm to improve layer adhesion. If molten filament is deposited on a room temperature prior layer, it will cool rapidly and pull away, reducing the quality of the bond between the two layers. The solution is to enclose the print area so the heat from the bed can warm the print in progress. An enclosed printer with a heated bed is an absolute requirement for printing with ABS.

Even if you have the proper set up, ABS is still more challenging. Generally, it has a higher tendency to warp off of the print bed. When this happens the part can be misshapen or the print can fail if the part detaches completely.

Lastly, if you are making parts that need to have a precision fit with other objects, with ABS you will have to factor in shrinkage into your design. With PLA, there is much less shrinkage, and results with true dimensions are more easily obtained.

PLA does not have the layer separation or bed adhesions issues that ABS has. Nevertheless, ABS does have its advantages. ABS is stronger than PLA. If you want a smooth, non-3D printed finish on ABS you have the option of treating the finished print with Acetone vapor to smooth out the surface.

Overall PLA is easier to use and is more predictable. The prints made from PLA are strong enough for most applications. Of course once you become familiar with PLA and have success with it you will probably want to experiment with other filaments.

Filaments with additives, such as wood or metal, will be more abrasive to the extruder tip. It is highly recommended to use a steel or high lubricity extruder nozzle. This will extend the life of the extruder. The critical feature of the extruder is the nozzle diameter. The printing process depends on a properly controlled layer thickness. If the nozzle become wider, it can change the width and height of the extruded plastic and adversely affect print quality.

There are excellent sources of information about the details of using various filaments. But starting with PLA is a great way to get going without having to do a lot of fussing along the way. For the record, the extruder temperature for PLA should be in the range of 190 C to 220 C. If you decide to heat the bed with PLA then 60 C is a good temperature.
 
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