Conveyor belts can extend the build area of a 3D printer
There are many remarkable things about FDM 3D printers, but build volume isn’t one of them. Although there is a market for dedicated large-format additive manufacturing systems, the typical build volume for a desktop extrusion printer is around 200 x 200 x 200 mm.
While that build volume may suffice for most small parts and prototypes, it presents an obvious limit on what you can do with a printer. A small build area restricts printer users to small-size parts and small batches of parts: larger parts need to be assembled from multiple smaller components, while large batches require a sequence of several builds with an operator removing parts from the print bed between each build.
But what if 3D printing wasn’t subject to such restrictions? What if an otherwise standard FDM printer could print extra-large parts and huge batches of individual small parts? With a conveyor belt 3D printer, both of those scenarios become possible.
This article goes over the basics of belt 3D printers, looking at how they work, their advantages and disadvantages, and the leading belt 3D printer models.
A traditional FDM (fused deposition modeling) 3D printer has a solid print bed covered with a build surface, above which a printhead deposits filament onto the build surface. Movement of the printhead and/or print bed allows for motion along the X-axis, Y-axis, and Z-axis.
A belt 3D printer replaces the conventional print bed and build surface setup with a conveyor belt, so the surface onto which the hotend extrudes material is constantly moving. Instead of moving the printhead or print bed by one step to proceed to the next layer, the belt moves fractionally along the Z-axis.
Additionally, the printhead is mounted at a 45° angle, and the combination of the moving belt and the angled nozzle enables printing of parts with theoretically infinite length along the Z-axis or a theoretically endless batch of parts.
Of course, while continuous printing allows for theoretically endless printing along the Z-axis, there are two physical constraints: the ability to support a long part as it stretches off the edge of the belt (usually achieved via runners or another type of support) and a limited supply of filament on a spool.
Needless to say, the most distinctive element of a belt 3D printer is the conveyor belt itself. The belt varies by printer: for example, the popular Blackbelt 3D printer uses a carbon fiber composite belt, while the Creality CR-30 uses nylon. The belt must be flexible enough to function as a conveyor belt while also being able to adhere to 3D printing materials. Some belts, such as those from Powerbelt3D, have a thin plastic coating specifically to help with part adhesion.
The next most important feature of a belt printer is the angled printhead, which allows for continuous printing along the Z-axis. Other benefits of the tilted nozzle include a reduced need for overhangs and support structures.
The most common motion system on a belt 3D printer is a Cartesian XY head, with the motion of the belt replacing the Z-rod movement of the print bed. As we will see in a later section, the 45° angle of the nozzle must be accounted for while slicing.
The third key feature of a belt 3D printer is some kind of system for preventing parts simply falling off the edge of the belt when they reach the end. For batch printing, a user may put a container under the edge for parts to fall into. For printing of extra-long parts, a roller system may be used to support the length of the part once it leaves the belt. Otherwise, the weight of the section of the part sticking off the edge may cause the entire print to tip up. Category leader Blackbelt sells a version of its printer that comes with a dedicated roller table for accommodating long prints.
In terms of printing capabilities, the main difference between belt 3D printers and regular FDM printers is the idea of infinite Z or continuous 3D printing. If enough filament is fed into it, a belt 3D printer can print endlessly without reaching the limit of a standard build envelope. But what belt printers offer in terms of continuity, they lack in quality: the inferior surface and stability of a belt printer can have a negative impact on part quality. The range of usable materials for belt printers is also very narrow.
There are also differences between belt and traditional printers in terms of adoption and usage. Clearly, belt printing is still a niche technological category, with few options available on the market, which limits its mass appeal. As such, its current user base is — despite the technology’s suitability for batch part production — dominated by hobbyists, tinkerers, and 3D printing experts, rather than professional or industrial end-users looking to implement a turnkey solution.
Mass produced belt 3D printers have only been on the market since 2017, when the Blackbelt printer was launched. However, hobbyists had made DIY belt printers before then, and the hobbyist community has been a constant driving force behind the wave of popularity for belt 3D printers. Research on the feasibility of continuous printing using a conveyor belt goes back to 2014 and possibly beyond.
Some of the most widely sold belt 3D printers are discussed here.
Dutch company Blackbelt 3D launched the groundbreaking Blackbelt 3D printer in 2017. At more than $10,000, it is on the more expensive side, but it produces high-quality prints and remains the benchmark for belt 3D printing.
The Blackbelt 3D printer is available as a standalone or roller table version (for supporting extra-long prints), and can be equipped with a standard Bowden extruder or a VarioDrive extruder for printing flexible materials. It has a semi-heated bed and a large frame.
Creality 3D, the Chinese developer of the popular Ender 3 printer, makes a belt 3D printer called the CR-30 or 3DPrintMill. It demonstrates the importance of the DIY printing community to belt 3D printing, as it was co-developed by the YouTube-famous engineer Naomi Wu. That being said, it is not open source like some other belt printers.
Equipped with features like a heated bed and filament runout detector, the Creality CR-30 has a low price of around $1,000.
Recommended reading: The best Ender 3 retraction settings
Another belt 3D printer born of the DIY community, the White Knight is a rugged printer which shares features with the CR-30, as it was developed by some of the engineers behind the Creality machine.
The White Knight is not sold as a ready-to-use printer, but parts for it can be sourced for about $2,000.
Brought to life via Kickstarter, the iFactory One Pro has a price tag of around $2,000. It is sold as a printer but requires extensive assembly before use. Features include an onboard camera for print monitoring, an intelligent error detection system, and a Wi-Fi-enabled Raspberry Pi 4 motherboard.
The IdeaFormer belt 3D printer has received some attention due to its very low price ($550 at the time of publication) and prominence on platforms like Amazon. Manufactured by the Zhuhai Bell Technology Co in China, the IdeaFormer has its fair share of fans and critics, with specs comparable to those of the CR-30. It may be a suitable machine for beginners due to its low price, but support options are limited.
Popular 3D printer company Printrbot shut down in 2018, but before doing so it launched its own belt 3D printer, the Printrbelt. Buyers may be wary of purchasing a machine without any support from the manufacturer, but the $1,500 printer produced good quality prints via its Kapton-coated steel belt and Raspberry Pi board.
Because of their moving build surface and angled printhead, belt 3D printers require different g-code to standard FDM printers. Consequently, not all slicer software supports belt printing.
Fortunately, Ultimaker Cura does support belt printing. Blackbelt Cura, a patched version of Cura that accommodates printers with a slanted gantry, is available to download from the Blackbelt website. Although the software is designed for the Blackbelt printer, it works with comparable systems such as the CR-30, White Knight, PrintrBelt, and Powerbelt3D Zero.
Another slicer that supports belt printing is Raise3D’s ideaMaker software, which has parameters such as belt raft offset and belt raft thickness.
Alternatively, users can implement a g-code script that adds some key belt printing instructions onto the conventional printing g-code (for example, offsetting each layer to accommodate the 45° tilt of the gantry). Bill Steele has written a script for this purpose, allowing users of other slicers like Slic3r and PrusaSlicer to use belt printers.
The benefits of belt 3D printing include:
Ability to print very long parts as single components
Ability to print large batches of small parts without interruption
Automatic removal of parts from belt as they reach edge of bed
Compatible with Cura
The limitations of belt 3D printing include:
Limited print quality
Limited print speeds
Belt material not ideal for adhesion
Only suitable for certain materials like PLA and PETG (not ABS)
Niche technology with limited developer and community support
Incompatible with standard heated beds
The ability to print extra-long parts or large batches of parts is a desirable characteristic of belt 3D printing. However, belt 3D printers cost upwards of $1,000, and some FDM users might not wish to invest in a whole new system to carry out continuous printing.
An alternative is to use a DIY modification for an existing FDM printer. One example is Paul Chase’s PrintShift, a system for turning a Prusa Mini into a belt printer. Although Chase doesn’t sell the mod in kit form, he provides a bill of materials and instructions for building it. Similarly, Powerbelt3D runs a project called Ender EZ Belt, which focuses on converting an Ender 3 into a belt printer. The company sells its own belts and provides downloadable files, a bill of materials, and instructions for the rest of the modification.
Another alternative to belt 3D printing — albeit a much more expensive one — is large-format additive manufacturing via machines from companies like BigRep and Thermwood. These machines do not have infinite Z-axis printing but have large build areas across all three axes, in addition to compatibility with a wider range of high-strength materials.
Recommended reading: Infrared cameras for large-format additive manufacturing
The recent advent of belt printers has opened up new possibilities in FDM 3D printing. Although first developed and championed in the hobbyist/DIY space, machines like the Blackbelt show that there are reliable, professional-grade solutions available for this niche technology.
Those considering investing in a belt 3D printer should, however, familiarize themselves with both the benefits and the limitations of the technology. Although many belt printers are capable of producing impressive “infinite-length” parts or large batches of smaller parts, they cannot match the quality of material versatility of traditional FDM printers. For parts that require extremely fine details or close tolerances, the technology may not yet provide an adequate solution.
Another important thing to note is that the learning curve for belt printing is, perhaps surprisingly, not all that steep. Those familiar with Cura will be able to migrate to Blackbelt Cura without issue, and those who run g-code commands directly will have no problem implementing post-process scripts which accommodate the unorthodox 45° angle of the belt printer’s printhead.
Overall, belt 3D printing provides a novel solution to the problem of limited build size on the Z-axis. Whether it is better or more cost-effective than large-format additive manufacturing (or simply running multiple print jobs on a traditional FDM printer) depends on the user and the project at hand.
 Dam DH, Le HN, Bui DT, Nguyen NL. A research on conveyor belt 3D printer in industrial applications.
 Günther D, Heymel B, Günther JF, Ederer I. Continuous 3D-printing for additive manufacturing. Rapid Prototyping Journal. 2014 Jun 10.