The Evolution of the Mosquito Hotend: Revolutionizing 3D Printing

Prototype 1 - Proof of Concept

The initial prototype version of the Mosquito Hotend introduced a simplistic yet innovative design to solve the persistent issue of tedious nozzle changes. It comprised a basic structure of a thin-walled metal tube connected to a hot block wrapped in Kapton tape. The hot block and thin tube were enclosed within a metal square with a brass nozzle; this version laid the groundwork for subsequent developments.

Though rudimentary, its significance lies in addressing a common challenge faced by hobbyists, marking the inception of the Mosquito's journey toward a user-centric solution.

Prototype 2 - Solidifying Form

The second iteration brought about significant material enhancements and a redesign that set it apart from conventional hotend structures. This version featured a machined aluminum heat sink that bears much resemblance to today’s Mosquito. The first version of the Bimetallic Heat Break was constructed from a thin-walled tube and two brass nozzles.

Repositioning the hot block below the original square design marked a notable departure from traditional setups—marking the first implementation of the rigid tubular structure that the Mosquito is known for. At Tom Sanladerer's advice, the hotend was lengthened to more closely resemble the form factor of standard hotend options for easier aftermarket integration.

This pivotal change improved performance and increased compatibility, setting a distinctive precedent that distinguished the Mosquito from its contemporaries.

Prototype 3 - Material Selection

Building upon its predecessor, the third iteration introduced subtle yet crucial refinements. An internal heat break fin was added to enhance functionality, and the screws used to connect the heat sink and hot block were reduced from M2 to M1.4 to improve thermal isolation.

This prototype introduced Slice’s signature retaining screw system for heaters and temperature sensors, a departure from the industry standard of clamping heaters and sensors into place. This decision removed unnecessary stress from the cartridges, extending their lifespan.

Materials evolved, utilizing production-grade components, marking a crucial transition toward better durability and performance. Most common hot blocks are typically machined from aluminum, which has a much higher coefficient of thermal expansion (CTE) than steel or brass nozzles. This requires the hot-tightening of nozzles with standard hot blocks, a less-than-ideal user experience. A copper alloy was the material of choice for the Mosquito, allowing for cold, one-handed nozzle changes.

This version solidified Mosquito's commitment to continual improvement and reliability—the first step toward a pre-production prototype.

Prototype 4 - Pre-Production

The key innovation was introducing a small heat sink on the heat break, revolutionizing temperature control, and marking the creation of the Bimetallic Heat Break silhouette we know today. This addition effectively managed heat distribution, curbing issues like heat creep and ensuring stable printing. The refined temperature regulation enhanced print quality and facilitated seamless transitions between filaments.

Despite no significant material changes, this iteration optimized the hotend's design for better stability and functionality. Prototype 4 solidified Mosquito's reputation for pushing the boundaries of reliability and precision in 3D printing technology and was the Generation-1 version that debuted at the 2018 Midwest RepRap Festival (MRRF).

Generation-2 (2018, Q4)

Mosquito’s heat break design was quickly modified after the product’s launch at MRRF. Once Mosquito was in the hands of our first customers, we noticed two key issues that needed to be addressed:

1. Much of our testing had been done with ABS or other engineering materials. Printing PLA, the most ubiquitous filament, was difficult and often resulted in clogs. 
2. Filament extrusion lines at the time were often inconsistent, resulting in out-of-spec filaments with varying filament diameters. The Gen-1 Mosquito was tightly toleranced, making it nearly impossible to print with an out-of-spec filament.

In late 2018, the Gen-2 Mosquito was released with an improved heat break geometry to accommodate PLA and inconsistent filament diameters better. This change vastly improved customer satisfaction and quickly made Mosquito an industry staple.

Generation-3 (2020, Q3)

After two years of use and community feedback, the Gen-3 Mosquito was released in 2020 alongside the debut of Mosquito Liquid. This revision included several crucial changes that drastically improved Mosquito’s performance:

1. Heat sink design was overhauled to accommodate the Prusa Research MMU and Mosaic Palette.
2. Rigidity of the heat break was improved for easier assembly and maintenance.
3. A lubricious coating was added to Mosquito and Magnum heat breaks to reduce internal friction.

These significant changes to the heat break changed how Mosquito could be utilized, opening the door to new and exciting applications that were previously inaccessible.

Generation-4 (2021, Q2)

The final Mosquito design revision that introduced the hotend available today was introduced in 2021—targeted at improving Mosquito’s abrasion resistance without changing the heat break’s form factor. 

While collaborating on hotend integration with RIZE 3D, it became clear that the Mosquito heat break could not handle some of the highly abrasive materials they utilized.

We partnered with RIZE to develop a heat break that could handle even the most abrasive filaments. After much iteration and testing, we revised the internal design of the heat break to improve its abrasion resistance. This significant improvement marked the transformation of Mosquito from a hobby-oriented accessory to an industrial component and initiated its adoption by major 3D printer manufacturers worldwide.

This heat break revision was rolled out to the public in Q2 of 2021, enabling abrasion-resistant printing for all Slice Engineering customers.