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3D Printer Filament Buyer's Guide

Posted by Alex R English on

This is intended to be a very basic Personal 3D Printer filament buyer’s guide for new 3D Printer users. Every single point presented here is worth a lengthy post, but this should serve as a top-level summary that might help you determine what plastic filaments will best suit your needs.

Additionally, see What Plastic Filament does my 3D Printer Use.

For corrections or ideas of other factors worth considering, share them with us at content AT protoparadigm DOT com.

Diameter

There are two common diameters of 3D Printer plastic filament, 1.75mm and 3mm. Your Personal 3D Printer is likely to use one of these. Each printer (or to be more specific, each extruder) is designed to work with one diameter of plastic filament and will not work with the other. Check your printers listed specifications or documentation to see which it uses. If you can’t find any indications of the diameter in those places check forums and user groups for the information, or ask there if you still can’t find it. If your printer came with some filament, you can also measure the filament to determine which of the two it is.

Some printers may use proprietary diameters that are slightly different from above. As above, read up to make sure your printer can use filament from suppliers other than your printer manufacturer. Likewise, if you’re shopping for a printer right now, make sure to buy one that uses standard materials so you have more choice when it comes to suppliers (which also gives you access to more materials, colors, etc.), or at least make sure there is a good technical reason for the proprietary diameter besides just locking you into the brand.

Filament diameters and tolerances will vary slightly from supplier to supplier, brand to brand, and possibly from product to product (different colors or different plastics), though filaments coming from the same supplier should be fairly close. There is a slight discrepancy between the nominal diameters for each size. For 3mm, the maximum diameter of the filament should not exceed 3mm. Our nominal, and that of many others is 2.85mm (and may range from 2.8 to 3.0 from different manufacturers - there is much more variance across the industry in target nominal diameters and overall specs on 3mm filament than on 1.75mm). This is in contrast to 1.75mm where the nominal diameter IS 1.75mm and not a maximum. This is one reason this smaller size is sometimes referenced as 1.8mm, which is used as a maximum dimension by some brands.

Filament can also have lumps (short sections where the diameter is larger than tolerances allow, usually only a few cm long), and neck-downs (short sections where the diameter is smaller than tolerances allow, again, usually only a few cm long). These will often cause jamming or stripping, but should be rare from a quality supplier.

Material

There are several materials available to print with. In general, the question for a new user usually comes down to ABS vs PLA. These are the two most common materials used in Personal 3D Printers. Each have distinct characteristics. The main deciding factor between ABS and PLA is probably going to be personal preference, though there are some limiting factors on each printer that may make one preferable to use over the other.

Here is a quick reference table of some of the differences between ABS and PLA. The details of each of these points can be found later in this post.
ABS PLA
Extrude at ~225°C Extrude at ~180-220°C depending on grade
Requires heated bed Benefits from heated bed
Works reasonably well without cooling Benefits greatly from cooling while printing
Adheres best to polyimide tape Adheres well to a variety of surfaces
Filament tolerances are usually tighter Finer feature detail possible on a well calibrated machine
Prone to cracking, delamination, and warping Prone to curling of corners and overhangs
More flexible More brittle
Can be bonded using adhesives or common solvents (Acetone or MEK) Can be bonded using adhesives
Fumes are unpleasant in enclosed areas More pleasant smell when extruded
Oil Based Plant Based

HIPS should also be mentioned here as a worthwhile printing material, even though less commonly used than PLA or ABS. HIPS has a nice look and feel, and is soft enough that it finishes very well. It prints similarly to ABS and can be bonded or smoothed with d-limonene as a solvent, which is a lot more pleasant and safe to work with than the solvents available for the others. It performs well in terms of impact resistance, but perhaps less well in other measures of mechanical strength. While it is generally thought of as a support structure that can be dissolved with d-limonene, it has its applications as a main print material as well.

There are other materials used for printing, in particular PET, PETG, PHA blends, Polycarbonate and PVA, but which are outside the scope of this buyer’s guide. Here you can find one of our early posts about printing with Polycarbonate. You may also come across blends of materials, such as a polycarbonate/ABS blend or polystyrene blends, but these too are outside the scope of this post.

Formulation

Each different kind of plastic can come in different grades. For instance, two grades of ABS we use are PA-747, which has been a staple in the industry for a good while, and MG94, which is still somewhat of a specialty/premium grade. 

Different grades may have different properties like process temperature, working temperature, flexibility, viscosity when melted, stickiness when melted, differences in look and feel or base color, etc. These can all affect both your ability to print with them and the quality of your prints or the difficulty of calibration. Many filaments are made from a single base grade and a pigment (or without, in the case of natural materials) but increasingly many are made from blends of multiple grades, even multiple types of plastic (may be referred to as a blend or an alloy), or other additives to change the characteristics of the material. These additives can include industrial process aids, impact modifiers, mineral fillers, compatibilizing agents used in blends, and many, many others.

Different products from different manufacturers (or different product lines) may be optimized for different properties including economy, filament extrusion (tighter tolerances, better look and feel of filament, etc.), printability (compatibility, print quality, etc.), environmental impact, printed part mechanical characteristics, finishing options, and any number of properties. The best advice to give on finding a formulation that works for you is to start sampling products from reputable brands to see what works best for your needs.

Strength

While many people will claim that ABS is stronger than PLA, we haven't found them to be substantially different. PLA is more brittle than ABS and will tend to splinter and break where ABS may tend to bend, but similar force is required for either to fail. It is more likely that you will find your print settings and design to be bigger contributing factors to the strength of printed objects than the type of plastic you're using (at least in broad terms, such as between PLA and ABS). Insufficient infill density, too few shells, delamination (layers pulling apart), and related problems may make your object weak even though the material itself is relatively strong. If your objects feel too flimsy or break too easily try upping infill, adding shells (perimeters), and tweaking your temperature and speed (to try to get better adhesion between layers) before you write off your plastic.

Printer Limitations

Does your printer have a heated bed? Is the bed capable of reaching temperatures over 100 degrees celsius? ABS tends to warp and peel, and often won’t stick well to an unheated, or under-heated print-bed. If you have an unheated bed, or one that doesn’t get hot enough, you’ll probably want to stick with PLA and other lower-warp materials.

Does your printer have a cooling fan blowing directly at the print area near the end of the nozzle? If it does, you’re probably good to go with either material, but if it doesn’t, ABS may be a better choice. PLA has a tendency to curl at corners and overhangs, a tendency that can be minimized with proper cooling. While good cooling will help either, ABS may fare better without a fan since delamination and cracking can occur when it is cooled too quickly.

Bed Surface Requirements

ABS and HIPS adhere best when printed onto a bed covered with Polyimide Tape (you will also see references to Kapton, which is a trademarked name for a brand of Polyimide Tape). PLA is a little more lenient and works great on Kapton, but also works well on blue painter’s tape. Polyimide Tape is more expensive than painter’s tape, but it goes a long way and can be replaced a little less frequently. Some people have luck printing PLA directly onto freshly cleaned glass (be careful not to drive your nozzle into your bed though). For more tips on getting your prints to stick, see  this post on bed adhesion tricks.

Temperature Resistance

ABS softens at a higher temperature than PLA, which makes parts printed in ABS more resistant to warping under higher temperatures. Keep in mind, we’re not talking about a huge difference; you’re still going to have a bad time if you print an oven rack accessory in ABS. For more moderate temperature situations, the difference may be important to you, it depends entirely on how you plan to use your printed object.

Printing Environment Considerations

Fumes can also play a factor. If you are operating your printer in a poorly ventilated environment, or where people will congregate, such as a classroom or your living room, you may find the fumes from long prints with ABS a bit overwhelming. PLA has a much more organic, less “plastic” smell to it. The strength or offensiveness of fumes can vary by grade and overall formulation as well.

The temperature of your environment can make a difference too. If your 3D Printer is open to the air and you’re printing in an environment with relatively cold air, you’re much more likely to experience cracking and warping with ABS than with PLA. When the ambient air temperature is very cold, such as in a basement or shop during the winter, layers of ABS will have more of a tendency to come apart and peel away from each other.

Finishing

After a print, you may need to join parts together, or clean up the surfaces to make them look nicer. PLA, ABS, and HIPS may be sanded, and can be painted with acrylic paints. Printed parts can usually be joined with adhesives (those that advertise they adhere to plastic) (we like super-glue for its strength, ease of use, and quick drying time).

ABS parts can also be solvent-welded with MEK (methyl ethyl ketone) or Acetone (especially in the form of ABS Glue, as we’ve detailed before), and can to some extent also be polished with these to create glossy surfaces. HIPS can be solvent-welded with d-limonene, which is safer than most other solvents and more pleasant to work with. Common solvents for PLA (chemicals you would use like MEK or Acetone are used with ABS) tend to be very dangerous, expensive, and hard to acquire.

Mechanical finishing such as drilling or reaming, thread-tapping, shaving, and others tend to work better on ABS and HIPS than on PLA, both because they are a little more malleable and because they are less brittle.

Environmental and Economic considerations

Like many other plastics, ABS and HIPS are petroleum products. PLA is made from vegetable waste (primarily from corn, but also from sugar beets and sugar cane). This is important to some people. Likewise, consider where your plastic is coming from. Supporting domestic retailers who use domestic suppliers helps reduce the energy used to transport goods, and also helps the domestic or local economy.

Color

Unpigmented filament, whether natural ABS with its creamy appearance, the lighter white of natural HIPS, or transparent natural PLA, are great materials to keep stocked. For one, from many retailers they tend to be less expensive, which makes them great for test prints and prototypes where color doesn’t matter. Unpigmented materials or others with some amount of translucency also tend to minimize the appearance of flaws, which is great for finished prints, but they actually make it more difficult to diagnose calibration issues while you are getting your printer settings dialed in since it is harder to see artifacts and defects with complete detail.

Colored filaments print slightly differently, and also make it somewhat easier to diagnose printing issues. We recommend calibrating your settings and printer to print well with a dark colored filament, which will generally give you good results with other colors, and with natural filaments. Selecting colors is completely subjective and is based entirely on personal taste and the kinds of items you wish to print. As you’re stocking up, think about how you’ll be using your printer and what colors you imagine you’d like the printed items to be.

Also note that some plastics are translucent or transparent where others are opaque. With few exceptions, ABS is usually opaque, though natural ABS has a milky, slightly (very slightly) translucent appearance, which is the same for HIPS. For the most part, any color of PLA may be offered as translucent, or opaque.

Packaging

Some people like coils, others like spools. There are pros and cons to each.

Spools (also called reels) are the easiest to work with. They store and travel neatly, dispense easily and evenly, mount conveniently, and look nice while helping avoid tangles. There are many accessories out there for mounting spools on your printer (or above it, or next to it, or under it...) or dispensing from spools set along side your printer on the desktop. The biggest down side to spools is the weight. When buying 1kg of plastic on a plastic spool, almost a third of the shipping weight can be the spool itself.

Coils (sometimes called "Air Spooled", which seems a bit hokey and misleading to us) are cheaper as you don't have to pay for the spool, and they weigh less, so shipping costs should be reduced. These are less common now than they were a few years ago. If you've got a spool with a removable flange that you can drop your coil onto, it can be just as easy to work with as buying spools; if not, you'll need some way to dispense it. Coils are more practical for smaller quantities of plastic filament, anything greater than a pound becomes unwieldy very quickly.

Supplier

Make sure you are buying from a good supplier. While we feel we’re a great supplier, we recognize that there are other good suppliers out there. We suggest considering the following factors when selecting suppliers.

Calibration

Keep in mind that when using plastic filament from different suppliers, you may need to recalibrate your 3D Printer. This isn’t necessarily difficult, but it does take time and effort. Keep this in mind when shopping around. While filament diameter is a major factor here, the formulation of the plastic will play a role here as well.

Price

Of course, price is a major factor for most people, but keep in mind not only the price tag of the plastic itself, but also the cost of shipping. Buy multiple spools or coils at a time to reduce per pound shipping costs. Also make sure to find information about any deals or promotions a supplier is offering.

Another important consideration in price is that if you buy cheap filament and wind up throwing portions of it out (whether throwing out the filament or failed prints attempted from it), you may not come out ahead (that stuff you're trashing cost money).

Tolerances

Make sure your supplier will stand behind their tolerances. Poor tolerances can cause problems ranging from poor surface finish to failed prints (which also mean wasted plastic, see Price above). See our post about the importance of filament tolerances for more information.

Customer Service

Make sure you select a supplier that is responsive to customers, has reasonable guarantees and return policies, and stands behind and understands their products.

Other Notes

As with everything, you will need to prioritize and decide which considerations are important to you when buying filament.

Hopefully this is helpful to you. If you have any suggestions for points we didn't hit on, please let us know at content AT protoparadigm DOT com. Likewise, if there are any questions you have about buying filament that you didn't feel were addressed here, let us know about that too.

Updates

(March 20, 2016)

This post originally went up some time ago and a number of things have changed. For one, there are now MANY more printers and printer manufacturers in the market. For this reason, we removed the table at the start of the post showing which diameters different printers use because that isn't the focus of this post. Other minor updates have been made to account for differences in printers, available products, and updated methodologies or understandings.

The information about grades of plastic has also been updated. When we wrote this post, all of the products marketed for the personal/desktop market were simple formulations of one of just a few base grades of resin along with a pigment. The industry has come a long way in that time. There are now more grades out there, and more manufacturers (like ourselves) using blends, additives, and proprietary chemistry to change the characteristics of the resins. Our former recommendation was to make sure your supplier stated what resin they are using, but that is no longer as helpful or as realistic. Formulations for filaments are now more sophisticated and considered trade secrets by manufacturers. For this reason the section above was renamed from "Grades" to "Formulation" and was edited to reflect these ideas.

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