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Anatomy of Sigma & Sigmax R19 extrusion system: Partnering with e3D™ & Bondtech™ manufacturers

This article is aimed at businesses and professionals that may consider introducing 3D printing technology to their facilities and need to know how the extrusion system works, especially in what makes the new generation of BCN3D printers unique. The following blog is just a summary of the full whitepaper. 

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The main focus resides on the new extrusion system incorporated in the BCN3D Sigma R19 and Sigmax R19, composed by top-grade industry-leading components: Bondtech™ Extruders, BCN3D Hotends by e3D™ and Filament Runout Sensors.


How does it work?

The Extruder System takes the raw material from a spool, pushes it through the Filament Runout Sensor, which will pause the active print in case of detecting a lack of filament, and enters into the Bondtech™ Extruder. This last mechanism pushes and pulls the filament to feed the e3D™ Hotend, the part that melts the filament to deposit it layer by layer.

E3D™ Hotends

The hotend can be described as the component of an FDM 3D printer that heats, melts and extrudes the material layer by layer through a nozzle. The whole structure of the hotend helps maintaining a consistent and accurate temperature, as well as providing an optimized thermal dissipation.

Parts of the hotend

The main parts of most hotends are:


In this article, e3D™ hotend assembled on BCN3D printers will be thermally compared to a standard hotend. How heat is transferred through the hotend defines the difference in quality and reliability between hotends.

The reliability of a hotend can be calculated through the temperature difference between the expected target temperature and the temperature actually reached by the hotend. Every hotend has its own structure to conduct the heat, so due to fabrication tolerances there will always be a tolerance when calculating the real temperature. The accuracy difference is shown in the following distribution:

The BCN3D hotends by e3D™ have considerably tighter tolerances than standard hotends, having at maximum a difference of ±0.5ºC. The majority of these hotends have no meaningful difference from the real temperature. Meanwhile, a standard hotend can be at ±2ºC from the real temperature.

When this accuracy has tight tolerances for all hotends, it ensures that each printer will behave exactly in the same way in terms of printing experience. This means that the printing profiles that BCN3D engineers prepare at their facilities will work perfectly in all BCN3D printers.

The heat dissipation, the heat transfer from the hottest parts to colder ones, has been analyzed through thermal simulations. The test has been done using PLA filament and heating the hotend at 220ºC (493 K):

When comparing both hotends, it can be seen that the BCN3D hotends by e3D™ easily dissipate the heat due to a high-performance heat sink and its number of lateral fins, which is considerably higher than a standard hotend – without changing the global dimensions of the injector. That means that e3D™ hotends can reduce the transition zone and have more control over the flow passing through itself. Standard hotends are more likely to have under-extrusion problems when 3D printing, because of the filament friction during the transition zone.

E3D™ know-how

E3D™ assembles more than 800 hotends per day, using high-precision machining that gives the hotends one of the highest reliabilities of the 3D printing market. During production, each individual hotend is rigorously tested and then hot tightened by E3D™. E3D™ use its own custom-built assembly equipment to semi-automate the assembly process and conduct quality control to ensure every hotend performs to the same high standard.

Bondtech™ Extruders

An extruder is the motor and all its associated mechanisms that push and pull the filament to carry it from the spool to the hotend. The main goal in this section is to understand how an extruder works and analyze why Bondtech™ Dual Drive extruders are probably the best ones that are currently in the 3D printing industry.

The main difference between Bondtech™ and other extruder manufacturers resides on the fact that Bondtech™ system consists of two high precision CNC machined and hardened steel drive gears, while the majority of the brands have only one drive gear. The symmetrical force from two gears, helps to secure the filament grip from both sides and minimizes the risk for under extrusion, filament deformation and grinding.

Parts of the extruder

To fully understand how this difference can affect the features of an extruder, some of its parts are shown below:

Comparison. The influence of the Gear Ratio

The Gear Ratio refers to the relation between the torque supplied by the motor and the Pushing Force of the filament. For Bondtech™ extruders it can be considered as balanced. It means that the extruder is able to feed relative fast extrusion prints and also deal with fast retractions. Besides, using this Gear Ratio increases the resolution of the system as the extruder will be able to supply more Pushing Force, allowing the printer to work with low layer heights.

Pushing Force for Bondtech™ Extruders is considerably higher than for any other standard extruder for all the studied materials. They ensure that all filaments will be printable for complex and fast prints, apart from obtaining a high printing resolution.

Bondtech™ know-how

Bondtech™ is a pioneer in extruders manufacturing and is a synonym of quality and reliability. Works with a huge volume of production and the assembly is semi-automatic, as the majority of the competitors assemble everything manually. Each unit comes assembled, tested and verified for optimal performance.

Filament Runout Sensor

At BCN3D Technologies, thanks to continuous development, we set out to improve BCN3D printers reliability and offer a solution to the problems of runout filament, through the Filament Runout Sensor (FRS).

This is a mechanical switch to detect filament presence, allowing to prevent one of the most common and frustrating failure reasons. In case of running out of filament during a print job, the printer will automatically pause and warn the user to load new filament and resume the print, saving time and money.

Parts of the FRS

The most important parts of an FRS are:  


3D-printable body

A 3D-printable body was a must, given the fact that several of the parts of BCN3D printers are manufactured in-house by other BCN3D printers, proving that FFF technology is a perfect manufacturing technology for relatively low volumes. This alone would help BCN3D save on prototyping time and production costs down the line. Thanks to 3D printing, the number of design iterations can be higher, ending up with a refined design. Using Mirror and Duplication modes from BCN3D R19 printers, lead times were reduced considerably to fulfill the printers demand.


The development of this new mechanism has allowed BCN3D to solve one of the most common troubles users found during their prints. The FRS goes in the same direction as the new hotends and extruders introduced before: to set a new standard in reliability. It is also an example of how BCN3D takes advantage of its own technology to develop its products, during the design and production phases, and proves that FFF 3D printing can be used to create end-use parts.


BCN3D has partnered with top world manufacturers such as e3D™ and Bondtech™ in order to equip BCN3D printers with the highest-grade components available nowadays in the 3D printing industry. The result can be found in the new Sigma R19 and Sigmax R19, which feature a new extrusion system composed by extruders powered by Bondtech™ and hotends optimized by e3D™, apart from a new filament runout sensor to detect material presence.


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