Which Filament Sizes Are Available?
There are only two diameters of filament available: 1.75 mm and 3 mm. Of the two options, the smaller diameter is the most popular in 3D printing because it allows users to make precision prints.
The 3 mm sized filament originated from its traditional use in plastic welding. Although it’s marketed as 3mm in diameter, it is actually more often 2.85 mm; the 3 mm number is denoted so users can easily distinguish it from the 1.75 mm option.
About 1.75 mm Filament
The 1.75 mm filament is the smallest filament that you can get for a 3D printer. For that reason, it is commonly used for complex print projects. However, despite its popularity, there are some pitfalls to using this filament.
Pros of 1.75 mm Filament
Users are typically most familiar with the 1.75 mm filament. You will have lots of choices as far as style goes, and this smaller thread size is more accessible for most to work with since it does melt faster and is easier to print to precise dimensions with.
The 1.75 mm filament is still the most widely available option; you will be able to find a lot more types of filament and styles if you go with the 1.75 mm filament compared to 3 mm filament.
Good for Precision
When you need a filament that can take care of the finer details, 1.75 mm filament will be your best option. There are several scenarios in which you would want a filament that delivers precise dimensions. For instance, if you are making mechanical parts, such as automotive components, then this smaller filament will allow you to finely tune the measurements.
Melts Faster than 3 mm Filament
Intuition would say that 1.75 mm filament tends to melt more quickly than 3 mm filament. This is certainly true as any plastic with less surface area will take less time to heat and melt. The big question is: why is this so advantageous?
With 1.75 mm filament, there will be less pressure required to melt the extruding material. The result is that you will have more chances to play with the flow rate settings. The 3D printer will also be able to push out the plastic at a higher volume. You can print out objects of the same surface area in less time.
Cons of 1.75 mm Filament
1.75 mm filament is certainly not without its cons. For one thing, it will be easier to break. The smaller filament is less forgiving when the material has become strained to some degree.
Getting Brittle & Breaking
Some users report having problems with their 1.75 mm filament getting brittle and breaking. One user, in particular, laments about having issues with 1.75 mm PLA (polylactic acid). Even if the prints come out fine, they may break at even the slightest touch.
It has been suggested that this is often a result of storage conditions. Excess humidity can cause the filament to absorb moisture from the air, leading to altered physical properties. Regardless of the cause, you will find that a 1.75 mm filament will generally be more susceptible to the environment’s effects than 3 mm filament.
This is because the narrower filament is much easier to break. It will not take much force to snap off a piece of 1.75 mm filament. In contrast, the 3 mm diameter product will be harder to break, even when it becomes brittle.
Will Be More Susceptible to Heat
Some filament types must be printed at high temperatures. For example, ABS has to be printed at a temperature of 240 to 270 degrees Celsius (454-528 degrees Fahrenheit). Temperature-resistance is thus considered a strong suit of this thermoplastic.
You won’t notice as much resistance to heat if the filament is 1.75 mm in diameter. In this case, the larger option may serve you better if you happen to have a printer capable of printing 3 mm material.
The effect may not always be appreciable, though, as 1.75 mm thread has served the 3D printing industry well. There are also types of filaments that are not nearly as resistant to heat as ABS is. With these other types of plastics, heat-resistant properties may not matter as much anyways. If you do care about heat-resistance, you should already be using ABS or another similar material to make prints.
Less Freedom with Flexible Filaments
This will also be discussed in further detail in the 3 mm section, but 1.75 mm filament will give you less freedom with flexible or semi-flexible filaments like TPU or ABS. You may find you can really test the limits of a flexible material through trial and error if the thread size is closer to 3 mm.
If the filament is 1.75 mm in diameter, you will certainly have less of a chance to accidentally stress it to the point of breakage. If you are unsure why this is the case, imagine having a thin rubber band and a thicker rubber band of the same size. The thicker rubber band will be more resistant to the stress you are placing on it than the thin rubber band.
About 3 mm Filament
This filament has fallen out of favor because it is usually a little harder to maneuver. You will not be able to use this filament with small extruder nozzles, leaving little room for intricate designs. However, there are still advantages to using 3 mm filament, as will be discussed below.
Pros of 3 mm Filament
If you are working with a flexible filament, you have probably learned the hard way that 1.75 mm diameter material is not the most forgiving. In some circumstances, the larger thread size certainly does make more sense.
Easier to Use with Flexible Filaments
Some types of filaments are more flexible than others. Polypropylene is an example of a filament that is known for being more flexible. As such, it is often used to make living hinges. These are often seen on the caps of bottles and allow users to shut and close the containers as they please. The flexible nature of this plastic makes it less susceptible to being broken.
Naturally, flexible filaments can be more durable if the diameter of the material being extruded is greater. Polypropylene is subject to warping, thanks to the fact that it has the lowest density among all the plastics used in 3D printing, so using a thicker diameter will increase its density and durability.
Less Likely to Bend in a Bowden Extruder
A Bowden extruder is a type of extruder where the motor is placed away from the carriage where the hot end is. This is an alternate option to a direct drive extruder that is less heavy. It can move faster than a direct drive extruder.
Since Bowden extruders are placed along the printer’s frame, the filament must travel through a long tube to reach the nozzle where the filament is released. 3 mm filament has been reported to be less prone to bending in a Bowden set up.
Greater Line Width
You could say that with 3 mm filament, you’ll be able to get farther with less material than you would with 1.75 mm filament. Even at 2.85 mm, the thread is still more than 1 mm greater in diameter. This greater line width will make this larger filament preferable for larger prints.
3D printer users have established a basic rule-of-thumb that the line-width should be up to 50% greater than the nozzle diameter. The 2.85 mm filament certainly delivers in this regard.
If you are trying to mass-produce prints and there is not too much precision involved, then the larger thread size is sure to service your needs.
Cons of 3 mm Filament
There are reasons that some users stray away from 3 mm filament, as will be discussed in further detail here. If any of these are major deal breakers for you, then you should probably be using 1.75 mm filament instead.
Fewer Style Options
As mentioned earlier, you are bound to find a wider variety of filament styles if you are using a 1.75 mm filament. The 3 mm filament has been reported to be going out of fashion in recent years.
Despite this, there are obviously still printers out there set up to handle 3 mm filament. You will generally not be able to use 1.75 mm filament in these printers without making some serious modifications.
Limited Nozzle Size
A disadvantage to the 3mm filament size is that you will be limited to using nozzle extruder heads sized large enough to handle the larger filament. 3D printer nozzles come in a broad range of sizes:
At the smaller range, you will have trouble with a 3 mm filament jamming in the nozzle. This will leave you to take steps to remove the filament from the interior of the nozzle head.
If you want to work with the smaller diameter nozzles, then your best bet will be to use a 1.75 mm filament.
You Need Larger Printer Components
One unfortunate aspect of printing with a 3 mm diameter filament is that you will need to use larger printer components to get the job done. The torque required from the stepper motor is three times greater than the requirement would be if you were using 1.75 mm filament.
You will likely need a larger stepper motor if you are going to work with a 3 mm filament. For commercial/industrial printing applications, this is not as much of a concern since these businesses probably have enough room for a large printer. But hobbyist 3D printer users are more likely only to have enough space for a smaller printer that can also work faster.
Which Filament Size Is More Affordable?
The most commonly-used filament is PLA (polylactic acid). It is widely available and affordable and is used to make prototypes and models like those typically used in academic settings. This is the reason why the prices for PLA are being used as a point-of-reference for comparing the cost of 1.75 mm filament and 3 mm filament.
Here are some examples of 1.75 mm filament:
Here are some examples of 3 mm filament:
The spools are 2.2 lbs. in mass. If you look, you will notice that they are all remarkably similar in cost. In terms of up-front cost alone, 1.75 mm and 3 mm filament are pretty much equivalent. Any differences in price would result from the costs associated with converting your printer to handle filament of a different size.
You may find it more expensive to get the parts to print out 3 mm filament effectively, as was referenced earlier. This larger filament requires users to use a motor with enough power to handle the heavier filament. The 1.75 filament is generally preferable for hobbyists who just want a small printer that can print with ease.
Are 3D Printers Capable of Handling Both Filament Sizes?
Many printers will handle both filament sizes, but as hinted at above, modifications will be necessary. With some 3D printers, it will be specified that you don’t even need to make hardware modifications to handle both 1.75 mm and 3 mm filaments.
Even if this is the case, you are still encouraged to add and separately name printers in the “Add Printer” section of the settings so that you will have the right printer and tool head combination prepared when you decide to switch between 1.75 mm and 3 mm filament.
Nozzle diameters also go a long way in determining whether you can use both filament sizes in your current setup. As previously mentioned, narrow extruder nozzles will have difficulty handling the 3 mm filament.
Which Size Filament is Best for Me?
If in doubt the 1.75 mm variation is standard and is easier to heat compared to the thicker filament and is always a safe choice.
You ultimately will have to go with the filament that is most compatible with your current setup. The differences between 1.75 mm and 3 mm (2.85 mm) filament aren’t necessarily significant if you are in the academic setting. However, in the professional setting where measurements to the thousandths of an inch make a difference, then your best bet will likely be 1.75 mm filament.
This is because you can really only use a filament that is 50% bigger than the diameter of the extruder nozzle. Most nozzles will fall within a range of 0.1 mm to 1 mm. A 3 mm filament will pretty much put you out of scope for using these smaller nozzles.
To be clear, there are situations in which a 3 mm filament will serve you well. If you are working with a flexible filament, you will notice that the 1.75 mm option may be too easy to break apart. The larger filament is indeed more forgiving in this regard.
You also may find yourself in circumstances where you need to mass print items larger in size. The greater line width of 3 mm filament makes it a more efficient choice to print large objects where fine details aren’t as much of a concern.