The extruder of a 3D printer is the part of the printer that does the actual printing; it can be likened to the print head of a typical inkjet printer in that it moves back and forth to deposit the material. The extruder is typically made of two main parts: the extruder body and the hot end.
The extruder body can look very different depending on the printer. Most off the shelf printers use a direct drive system where the extruder stepper motor directly drives the plastic filament into the hot end; these extruders typically use the smaller 1.75 mm filament. Another common extruder system uses gears to drive the filament into the hot end; these are usually found on DIY printers that use the larger 3 mm filament.
The hot end is the business end of a 3D printer. It is the end that gets hot, as the name suggests, to melt the plastic filament and deposit it on the part being printed. The hot end consists of three main components: the nozzle, whose size dictates part quality and print speed; the heater cartridge, which produces the heat needed; and the heating barrel, which the plastic filament is fed through to be heated. The typical extruder set up looks like this diagram.
Another type of extruder exists called the Bowden extruder. This model separates the extruder body from the hot end, instead connecting them via a PTFE tube that the filament travels through. Bowden extruders allow the relatively heavy extruder body and motor to be mounted on a printer’s frame instead of on the moving carriage most printers use. This allows the carriage to be lighter and move faster, allowing faster prints; however not a lot of force can be applied to the filament to push it through the hot end, and they can be difficult to switch filaments with. The Ultimaker is a good example of the Bowden extruder system.
The best extruder depends on the printer you want. The best way to decide is to first look at the capabilities you want your printer to have and choose a hot end based on your requirements. From there you can decide the best way to feed it with the extruder body. When choosing an off the shelf printer, extruders are usually unique to the model, so looking at what the printer’s temperature capabilities and print speed is about the best you can do. For the purpose of this article, we will be looking at extruders as though you are trying to build your own printer.
Once you have decided on the right hot end for your printer, the next step is how to mount it to the printer. The most common type of mount is the J-head mount; a cylindrical mount with a slot about 4 mm from the top that allows the extruder to be mounted with ease. The slot fits into an extruder mount, usually made of wood or metal (plastic will melt!); while the cylinder usually fits into a hole in the extruder body, lining the hot end up with the filament for easy feeding.
The extruder body is usually a personal choice. They can be either direct driven or gear driven, however direct drives are favored for their simpler design. If you decide to print with 3mm filament, a gear drive may be your best option as they provide more force to the filament. Extruder bodies can also be customized, especially gear models. A simple search on .STL sharing sites will yield dozens of unique gears and extruder bodies.
One other thing to consider is how many extruders you want on your printer. Most printers just have the one extruder, but several models go for a dual extruder design. Dual extruders offer the ability to print in two colors or even different plastics at the cost of print time and a smaller print volume. If you are considering a dual extruder system make sure that your control board can handle having two extruders, and that both hot ends are level when you go to print.
The hot end is arguably the most important part of the printer, without it you simply could not print. Is also The most important features to look for in a hot end are the nozzle, max temperature, filament size, and voltage.
You want to make sure the voltage of the heating cartridge matches other systems on your printer; most are 12V, but 24V is common too. There is no real advantage of one voltage over the other, it just depends on the components you use.
Filament size is dictated by what you want to print. 1.75mm is the most common these days, but many people still prefer to use 3mm. Make sure your hot end matches the filament you intend to use, a 3mm hot end will not work with 1.75mm filament!
The nozzle is very important as it dictates how much plastic can be printed at a time against how detailed your print can be, as well as your maximum layer height. The most common size nozzle is .4 mm, which is a good medium between the speed of .5 mm nozzles and the detail of .35 mm nozzles. Larger and smaller nozzles exist, however most people stay within the practical .35 to .5 mm range. Nozzles are typically made of brass and can be screwed onto or into the heating cartridge or heating barrel depending on the model of the hot end. It is a good idea to be sure your hot end has interchangeable nozzles.
Finally, the max temperature a hot end can reach will dictate what plastics you can print with. Many hot ends max out at temperatures suitable for PLA and ABS based filaments only, maybe nylon. These hot ends are usually limited by a PTFE liner used on the inlet of the hot end (by the J-head mount) that acts as a heat barrier between the hot end and the plastic extruder body. A popular alternative is the all-metal hot end, which does away with the PTFE heat barrier in favor of active cooling with a fan. All-metal hot ends also have the advantage of being able to reach much higher temperatures and be compatible with any plastic filament on the market.
Below is a comparison of some of the best hot ends and extruder combinations on the market today.
Have you had enough with clogged extruders that mess up the print job? Or have you had to change the stock extruder because it did not print well with a non-proprietary filament?
Well, fret no more and look no further because Flexion has heard and answered the prayers of you and countless other 3D printer enthusiasts suffering from the same. Say hello to the Flexion Retrofit kit, a replicable single extruder kit designed for a range of available 3D printers.
Why is it the Best?
Available in 2 makes for the diversity of available printers, the whole kit comes with all mounting hardware and 4 nozzle (0.2, 0.3, 0.4 and 0.5 mm ) outlets. In just 1lbs of net weight, the extruder prints at a much faster rate as compared to stock or upgradable extruders within the same price range. The kit is developed with a self-cleaning mechanism which means your print job won’t get stuck at any point, and allows you to add more filament when the current pack finishes. The high pressured discharge allows a consistent print with the more rigid ABS and PLA filaments, making printing with flexible filaments (flexible PLA, TPU, TPE and other non-proprietary filaments) an unforgettable experience.
Moreover, the insulation upgrade, cleaning brush and other accessories available make maintenance a snap and the fact that it’s removable means it can be replaced by other versions (dual extruder etc.) of the same make. The drive gear, heating block and the feed barrel have been developed using precision modules allowing the extruder to channel feed rates, printing speeds and extruder pressure in the most optimal way for your printing job.
Upon reception, the box that holds the DIY kit has all the parts neatly assembled in a foam case for with each part clearly described in the user manual which also directs you on how to disassemble your stock extruder and install the kit. Flexion has even provided STL files (here) for the fan mount that you can print yourself when replacing the plastic plate, accompanying most stock extruders. The printable plate/fan mount (for those worried about heating issues) also has holes allowing to easily access the hex-screws on top of the kit without having to remove the plate which sits on top.
All in all, if you’re unhappy with your prints for any reason, and are thinking about replacing the extruder, get the Flexion retrokit extruder and print like never before!
Hot ends with the PTFE heat barrier such as 3D CAM’s MG Plus hot end are not as common as their all-metal counterparts mostly because of their temperature restrictions. The PTFE lined hot ends do tend to be cheaper, as all metal hot ends require special machining for their cooling fins; and are able to print a little faster than all-metal hot ends because the PTFE liner allows the melting area of the barrel to be longer, which melts the filament faster.
Quieter (no dedicated cooling fan)
Typically faster due to larger melting area
Easy to change nozzles
Hard to find, older design
Limited to PLA and ABS only, some models can go a little hotter but this is rare
Typically paired with: Geared or direct drive extruder bodies. The Wade’s Extruder is the most popular on DIY printers.
Lulzbot Hexagon Hot End with TAZ Single Extruder body
The Lulzbot TAZ extruder is an all-metal of end found on their TAZ and Lulzbot mini printers, with the mount used in their TAZ printers. This hot end is capable of reaching 300C, which is hot enough to print with any filament on the market today (Lulzbot recommends not using filaments with carbon fibers, as these damage the nozzle). Lulzbot makes their design open-source, or non-proprietary, too. This usually means documentation is easy to find on their parts and makes hacking easier.
High temperature allows for printing of any material
Hexagon hot end can be found by itself and is compatible with DIY printers
Shorter than other hot ends, allowing taller prints.
Easy to change nozzles
Requires active cooling fans to prevent melting extruder body and printer jams
Typically paired with: TAZ Extruder body, DIY extruder bodies.
The E3D V6 is the latest version of the popular E3D all-metal hot end. The all-metal claim is a bit false, though, as the E3D does come with a PTFE tube that is inserted into the hot end for thinner (1.75mm) filaments. When the PTFE tube is not used, the E3D can reach 300C with ease, and print with just about any filament on the market, just like the Hexagon. The PTFE Liner never enters the really hot section of the E3D nozzle, so a meltdown is not a concern if used properly.
High temperature allows for printing of any material
Easy to change nozzles
PTFE liner tube improves smaller filament performance but limits max temperature
Needs active cooling fan to prevent melting extruder body and printer jams.
Typically paired with: Any J-head compatible extruder body.
The extruder of your printer plays a vital part in determining your printer’s capabilities. Max temperature, print speed, filament size, power requirements, control board, and even layer height are affected by the choice of hot end alone. The area of the print bed alone is the only important statistic of a printer not affected by the extruder. Choose wisely the best 3D printer extruder when deciding; stay informed and look into every option for the best results.
If you just want to get started with the best recommend product, see the table below: