Project Overview

Welcome, to the project page of one of the largest DIY 3D printers! Here you will find the BOM, CAD model, wiring diagrams, printing parameters, and other particulars that did not make it into the YouTube series. Please note that this information supplements but does not replace the build series, so definitely watch the videos. For questions, comments, and to share your build, please post to the forum.

SAFETY DISCLAIMER: This is a dangerous build that draws close to 8 kW when heating up to temperatures >300°C. Poor electrical wiring may lead to a fire and/or electrocution. If the printer is enclosed, then there is a possibility that a person could become trapped inside of the heated chamber. Electrical and safety codes of your municipality should be adhered to. Dr. D-Flo is not responsible for any damages, loses, or injuries because of any individual attempting this project or operating the printer. Experience with building 3D printers, electrical mains wiring, and overall, mechanical knowhow are musts.

License: This project is licensed under BY-NC-SA 4.0. Users are allowed to adapt and remix the work but all contributions must be distributed under the same license as the original (e.g., noncommerical). The base 3D model cannot be redistributed, but modifications that unlock new features or significantly improve the base function of the printer can be shared. For any questions on this license please contact Dr. D-Flo.

Versions

This is an ever evolving and improving project. Below are the different versions of the Large Format 3D Printer (LF3DP). The later versions will be more capable, but also more expensive. Most of the mechanical components (e.g., frame, bed, and gantry) are preserved between versions. This is a DIY project, so feel free to mix and match versions depending on budget and requirements.

LF3DPα – The Alpha version uses a standard Tr8*8-2p lead screw with open-loop (i.e., normal) stepper motors. The end stops are mechanical switches, and all electrical components are wired directly to the mainboard (versus CAN BUS). The Alpha version is seen in videos 1-4. A complete 3D model and configuration files are available for the alpha version.

LF3DPβ – The beta version upgrades the stepper motors to closed-loop motors on all axes and electromagnetic brakes are used on the Z-axis. Duet 3 1HCL tool boards are used for each motor to minimize wiring through CAN-FD BUS connections to the Duet 3 Mainboard. The Beta version is seen in video 5. Configuration files are available for the Beta version, but the CAD file is largely the same as the alpha.

LF3DPγ (Coming Soon) – A high helix lead screw and nut will increase the travel speeds to greater than 100 mm/s. This version is still in testing and is likely to require larger motors.

Features

All the benefits of a hobbyist 3D printers scaled up significantly! Upload a model, click print, and create. Manufacturing of largescale prototypes has never been so easy.

Close up of pellet extruder printing.
Massive Print Area: 1120 x 1120 x 1100 mm
With a build envelop just shy of 4 feet in all dimensions, the LF3DP is capable of printing furniture and other large objects.
High Volumetric Output Extruder: 1 kg/hr - 450℃
This printer comes standard with a MDPH2 extruder by Massive Dimension, which can extrude at a rate of 1 kg/hr. Unlike typical filament extruders, the MDPH2 uses a screw to convey and liquify plastic pellets before the molten material is pushed out of a large nozzle (1 to 5 mm extrusion diameter). Please note: This printer can also be configured for other high flow rate extruders, such as the Typhoon and Pulsar by Dyze Design.
Affordable Pellet Feedstock
Pellets are the cheapest form of feedstock for any plastic-based manufacturing process. Save 50-75% of material costs by using pellets instead of spools of filament. Concentrated colorant can be added to the virgin material to achieve any color in the rainbow without requiring large amounts of storage. Recyled material can also be used for sustainable material printing.
Powerful Heated Bed: 5500W - 150℃
Most pellet extruder-based 3D printers or robotic arms require clamps and other forms of mechanical fixation to prevent large parts from warping and being dislodged from the print envelope. The LF3DP uses a 5500 W heated bed to keep the initial layers from cooling too quickly and lifting off the print bed. The ultra-smooth borosilicate glass plate provides an even printing surface, which can be augmented with PEI tape or your favorite bed coating for more difficult to print plastics.
Automatic Gantry Leveling
Inspired by the quad gantry leveling system of smaller CoreXY 3D printers, such as the Voron 2.4, the LF3DP uses a probe and 4 independently driven Z actuators to automatically square the gantry to the glass build plate. The result is a consistent nozzle distance (< 0.5 mm of deviation) for an even first layer.
Compact and Enclosed Form factor: 1600 mm x 1600 mm x 1800 mm
The enclosure is only 30% larger than the print bed, creating a small footprint for a printer capable of such massive prints. The enclosed build volume and high-powered bed heater allows polymers, such as ABS and Nylon to be printed.
Familiar Software: SuperSlicer
Import the LF3DP configuration files into or use your favorite slicer to create printable files. Upload the G-code to the LF3DP’s Duet web interface.

Limitations

Anyone who has owned a hobbyist 3D printer has wished at least once that their bed size was bigger. However, going from the standard 250 x 250 mm build plate to one 5x larger in both X and Y comes with a premium price tag and some limitations that you may not have anticipated. Please consider carefully if large format 3D printing is right for you and your business by reviewing the limitations below.

3D Printer Pellet Extrusion Failure

A spectacular explosion of plastic after the X-axis actuator failed.
Travel Speeds
The LF3DPα tops out at 60 mm/s (3600 mm/min or 140 ipm) print/travel speed. However, it’s max speed is even lower (~ 40 mm/s) if stock components are used (see Nut Block section). A lead screw transmission was chosen due to its ability to accurately move the heavy print head, which weighs 11.3kg or 25lbs when summing the weights of the extruder, full pellet reservoir, and aluminum carriage. However, the tradeoff for using a Tr8*8-2p lead screw is its low max speed. A more aggressive (higher pitch) lead screw could be used, but this would require larger motors, which would increase the cost of the build. The upcoming LF3DPγ will use a high helix screw to address this limitation.
Cost of Print Failures
This limitation is inherent to all large format printers but print failures at this scale can be both expensive and damaging to the printer. Warping and blobs of extra plastic can cause the extruder to collide with the printed part. Typically, the heated bed and careful tuning of print settings mitigate these potential collisions, but LF3DPβ version uses closed loop stepper motors to detect misstep steps and pause the printer to avoid wasted plastic.
3D Model Optimization
3D models that print well on a normal filament printer may print poorly or not at all with a pellet extrusion-based system. To have a high volumetric flow rate, pellet extruders have a large hold up of molten polymer, which oozes during non-printing movements. Carefully tuning the coasting parameter (i.e., prematurely stopping the extrusion before a non-print move) can eliminate most of this oozing and resulting stringing, but it is best practice to create models that can be printed continuously. The other issue with pellet extruders and printing large extrusions widths is that the polymer will integrate tightly with the previous layer because the thick extruded fiber has a high thermal mass. This is great for the mechanical strength of the part, but bad for support material removal. Consequently, support material printed with a pellet head will require destructive methods to remove it (sawing, hammering, grinding, etc.), which often damages the part. Designers should look to remove overhangs from their model. It should be noted that pellet extruders are capable of some amount of bridging as seen when printing the step stool in video 4, but this requires slow print speeds and a high CFM part cooling fan.
High Temperature Prints
One of the original goals with this printer design was extrusion and subsequent printing of performance plastics. This includes materials such as PEEK and PEI, which have high melting points. The MDPH2 extruder has a maximum temperature of 450 ℃, which is perfect for these plastics. However, a mixture of technical and financial limitations has thus far prevented the printing of these plastics. The high chamber temperature needed to prevent warping would require heating coils, which would draw even more amperage, and thick insulation would be needed to trap the heat in. The X-axis stepper motor and servo motor on top of the extrusion head would have to be water cooled to prevent their insulation from melting. But perhaps, the biggest challenge would be keeping the throat of the extruder cool enough, so that pellets do not bridge at the bottom of the feed tube, blocking the flow. In a heated chamber, the cold end fans would be less effective, allowing heat from the hot end to flow to where the pellets are fed from the hopper. Even a slight softening of the pellets can cause them to stick to each other. This would necessitate water cooling the throat of the extruder.

3D Model & Mechanical Design



There is currently no manual for putting together the printer, but the CAD model contains the location and type of each component in the assembly. Explore the model on your browser or download the file and open it with Fusion 360. The video series shows the order in which each sub assembly was put together.

BOM

  Google Sheet BOM

The BOM may contain affiliate links that provide monetary kickbacks to Dr. D-Flo. These funds are used to pay for this website and future projects.

  Wiring

  Disclaimer: Mains electricity (110 - 220 V) is dangerous both to yourself and your property. Improper technique can lead to electrocution and/or fire. Always unplug circuits and check with a multimeter to ensure a circuit is de-energized prior to begining work. Follow all electrical codes and consult with an electrician before attempting this project. The wiring diagrams and information provided are for reference only. Dr. D-Flo assumes no responsibility for your property or health if you take on this DIY project.


Power Supply

With the printer’s current configuration, the extruder heating element, extruder servo amplifier, and 24 V power supply for the duet mainboard and associated electronics are powered by a 15 A 110 V circuit. The 5500 W heated bed is on an independent 220 V 30 A circuit. This setup allows users to forgo the heated bed and use mechanical restraint (brim, clamps, etc.) to hold prints onto the bed. Therefore, a normal house outlet would work for powering this printer, a benefit of this design. It is easy to modify the electronics to run off of 220V. The only substitution required is new contactors that have coils rated for 220 V. Consult the manuals for the 24 V power supply, servo motor power supply, and MDPH2 extruder to use 220V power.

AC power connections for DIY large format 3D pritner
To enlarge the image, right click, and open image in new tab.

The two contactors are for switching on/off the 110 V and 220 V circuits. When supplied 110 V the electromagnet inside the contactors closes the circuit. If this circuit is interrupted, then the contactors will spring open cutting all power to the printer. An emergency stop button and the thermal fuse located near the heated bed are two possible ways to open the coils’ circuits. The emergency stop button is pressed by the user when a fault is detected or the thermal fuse blows when the bed or the chamber reaches too high of a temperature (i.e., thermal runaway).

Not pictured: Panel mount disconnect switches were also used to disconnect incoming mains power.

Contactors do not protect you and the printer from a short circuit. Electrical shorts result from poor wiring or a failed electrical component (e.g., silicone bed or ceramic heaters in the extruder). Shorts can cause electric shocks if the user touches any metal component on the printer and can cause arcing, a serious fire hazard. Shorts are more likely to occur near heating elements as wire insulation and terminations are often made from plastic materials, which can soften and melt at high temperatures, revealing the bare conductor. All wire insulation and terminations should be selected for their ability to withstand the temperatures of the printer’s chamber and heated bed. If there is a potential for the wire to come in contact with the extruder’s barrel, then it must be rated for > 500C.

Proper grounding of all electrical components is necessary to shut power to the printer if a short forms. The frame, printer bed, extruder, electrical cabinet, and solenoid cabinet all require a robust connection to ground. Wire these components in a star pattern to prevent ground loops.

Your local electrical code may require additional safety features.

Configuration and Slicer Files

Pellet Conveyance

Animation of pellets flowing in a tube for a pellet extruder for large format 3d printing

With filament 3D printers, the continuous extrusion of plastic is largely taken for granted. Pellet extruders, on the other hand, are more prone to material feeding issues as they are fed by discrete pellets and not continuous filament. While infrequent, pellets can fall into an orientation where they bridge across the diameter of the feed tube, blocking the flow of material behind them. Even a short interruption in the pellet flow will result in gaps between printed layers. Of course, a permanent block will cause a print failure. Print failures on this scale are quite frustrating as they generate a lot of wasted material and are costly. So, any system that keeps the pellets flowing is worth investing in at this scale!

There are methods for both detecting blockages and clearing bridged pellets, both of which are sold by Massive Dimension. A pressure transducer addon can detect a change in pressure, such as when material is not flowing into the barrel. This addon is quite expensive (~$6k) but is worth the cost because the printer can be paused in response to a pressure drop, and the jam can be cleared manually.

Pellet Vibrators

99% of all bridged pellets can be cleared by applying target vibrations to the throat of the extruder. Vibrations increase the fluidity of plastic pellets, allowing them to change orientations for continuous feeding. Massive dimensions sells a pneumatic vibrator called the Feedstock Agitator that is compatible out-of-the-box with the MDPH2 extruder. In video 5, a custom feedstock agitator was built as a more cost-effective solution that can be integrated directly with LF3DP’s controller board. Electrical connections are illustrated above, and pneumatics are below. The vibrator does not need to run continuously. Instead a duty cycle of 5 seconds on with 1 minute off is sufficient.

Two different vibrators for pelleted feeeding on 3D printer pellet extruder.
There are two options for pellet vibrators: CVT-P-1 Turbine and VM-38 Linear piston

Please note: Throat adapters were designed (and STL files are supplied) to support both the CVT-P-1 turbine vibrator and the VM-38 linear piston vibrator manufactured by the Cleveland Vibrator Company. While the CVT-P-1 was featured in video 5, there was an issue with the bearings and had to be returned after several hundred hours of operation. Linear vibrators are more robust, but they should be mounted perpendicular to the target of the vibrations. However, there was not enough space inside of the MDPH2 housing for this arrangement, but enough pellet movement was observed when mounting the vibrator parallel to the throat. The turbine vibrator is the better design because the produced vibrations are omnidirectional but is more expensive, and my unit had a bearing issue.

Pellet Conveyance from Bulk Material Storage

How a Venturi Vacuum system moves conveys pellets for large format 3d printing or for other forms of plastic processing

Due to their weight, only a small volume of pellets is stored on the printhead for immediate use. Once these pellets are exhausted, material from the pellet bin needs to be transported to the printhead. There were quite a few recommendations in the comment section of video 4 for ways to move pellets both mechanically (e.g., Archimedes screw) and pneumatically (e.g. Venturi vacuum). But the simplicity of a Venturi system is best suited for large format 3D printing. The only requirements are a source of compressed air, a solenoid to control the flow of air, a Venturi vacuum generator, and a tube to carry the pellets. Outside of the solenoid opening and closing, there are no moving parts.

The Material Conveyance Unit sold by Massive Dimension is a stand-alone Venturi vacuum system. When the capacitive sensor on the print head detects more pellets are needed, it directly triggers the solenoid, and the pellets are sucked out of the pellet bin and flow to the printhead. Once pellets have been replenished the capacitive sensor switches off the solenoid. In a perfect world, this setup would function as intended, but if the pellet tube ever becomes disconnected from the print head or the pellet bin runs out of pellets then the conveyance unit will remain on indefinitely with the first scenario causing all pellets stored in the bin to be thrown throughout the room. The mess that this can cause was seen at the end of video 4.

What is missing is a watchdog timer that turns off the solenoid if the printhead fails to fill in a set amount of time. For this reason, the capacitor sensor and solenoid were wired to the LF3DP’s controller board to carefully monitor the flow of pellets. If the bin runs out or the pellet tube becomes dislodged, then the controller board will turn off the pellet conveyance system and pause the printer.

The material reservoir that comes with the Material Conveyance Unit features a right-angle connection for the incoming pellet tube that is ideal for motion setups involving a robotic arm but not gantry systems such as this printer. Included in the available files is a material reservoir with a vertical connection, which was designed to be SLS printed. With the vertical connection, the pellet tube is not likely to fall off.

Pneumatic Components and Circuit

Configuring pneumatics for large format 3d printer

There are two pneumatic devices that need an intermittent supply of clean, dry air: the Venturi vacuum generator and the vibrator. The Venturi vacuum is rated for 50 CFM at 90 PSI, which is a tremendous amount of air for a hobbyist operation. Fortunately, the pellet conveyance system only takes < 2 seconds to refill the printhead. A 2 hp air compressor with at least a 10 gallon tank, such as the California Air tools 10020C, is sufficient for supplying air and only requires a common 15A 110V circuit. However, if the vibrator is set to run at a higher duty cycle than ~8% (5 seconds on and 60 seconds off), then a larger air compressor may be required.

The air supplied to the Venturi pellet conveyance system must be bone-dry because moisture can greatly affect the extrusion process by increasing unwanted oozing or even degrading the plastic (e.g., PLA hydrolytically degrades at high temperatures). If you see pockets/bubbles forming in the extruded plastic then either the pellets, air supply, or both are contaminated with water. Pellets should be dried according to the manufacturer’s specifications and an air dryer should be installed after the compressor. In humid Tennessee, three air dryers were tested with the LF3DP:

Product Name: Manufacturer Desiccant Volume Desiccant/Filter Maintenance (Total Print Time)* Cost
M-60 NPT Sub-Micronic Filter** Motor Guard N/A (Filter) ~48 hrs $82
Air Cleaner/Dryer (PA208503AV) Campbell Hausfeld 0.1 L ~24 hrs $99
Max Dry USA Weld 2L ~500 hrs $450
*A PneumaticPLus QLK32 Passsive Radiator was used in line before the dryer. Desiccant/Filter replacement times may vary.
** With the Motor Guard filter it is difficult to determine when to replace the filter as there is no colometric readout. Desiccant-based air dryers are preferred for this reason.

While the Venturi vacuum system works best at 90 PSI (0.6 MPa), the vibrator can run efficiently from 20 to 80 PSI (0.14 to 0.55 MPa). The vibrator should be supplied with the lowest pressure that still provides enough vibrations to prevent the pellets from bridging. Using a lower pressure will increase the lifespan of the vibrator, but it will take trial and error to determine the minimum pressure required.

Inner workings of a linear piston vibrator
Components of a linear piston vibrator

The lifespan of linear piston vibrators (but not turbine-variants) can also be increased by powering them with lubricated air. Inside of a linear piston vibrator is a weighted slug that bounces back and forth. Without lubrication the channel and the slug will both wear down allowing for more air to pass by without driving the slug, resulting in less vibrations. An inline lubricator can be installed after the regulator, but an oil separator on the other side of the vibrator is required to keep oil from contaminating the bed and the print. Plastic does not adhere to oil covered surfaces.

Pellets and Recycled Material

Dr. D-Flo next to a Supersack of PLA pellets for his Large Format 3D Printer
Dr. D-Flo next to a SuperSack of 1250 kg of PLA pellets.

While pellet extruders and supporting pellet conveyance systems have high upfront costs, significant cost savings can be had when buying pellets compared to filament. Spools of filament are commonly sold in 1, 2, 4, or 10 kg quantities. However, when purchasing larger spools not only can you run into compatibility issues with your 3D printer, but also, the cost savings are not nearly what you would expect. For example, 3DXTech sells their Ecomax PLA in 1 kg and 4 kg spools for $32 and $110, respectively. The larger spool saves you $18 or about 0.5 kg of filament, which is better than no savings, but 3DXTech will also sell you 10 kg of PLA pellets for $100. This example highlights two findings: 1.) plastic pellets are very cheap and 2.) the process of re-extruding the pellets as a filament contributes greatly to the ultimate cost of a spool.

When purchasing pellets in even larger quantities, such as a 1250 kg Supersack from Filabot, PLA pellets will cost $6 or lower per kg. If you plan on incorporating large format 3D printing in your business, then be sure to budget the equipment that can unload, move, and dry these large quantities of pellets. Large quantities of pellets can be dried with Massive Dimension’s Plastic Pellet dryer.

The LF3DP is compatible with thermoplastics that have a lower melting point than the 450℃ max extrusion temperature of the MDPH2. However, as discussed in video 5, some plastics such as ABS emit noxious volatile organic compounds (VOCs) and require industrial exhaust systems to print safely. Additional plastics, such as ABS, ASA, PC, PPS, PEI and PEEK, that are dimensionally unstable and must be printed in a heated chamber are also poor candidates for the current configuration of this printer. Insulation and active chamber heating can be added to the LF3DP to support these resins, but these upgrades will require changes to frame and will significantly increase the power draw.

The current design is most suitable for printing:

Recycling Plastics with Large Format 3D Printing

Many see Large Format 3D Printing as one possible avenue for breathing a second life into recyclable plastics. Old soda bottles can be crushed up and printed into park benches or even art installations. While there are startups that have demonstrated the feasibility of this idea, it is important not to overlook the technical challenges of printing old plastics. Perhaps the most pressing issue is sourcing a stream of recycled material that is:

These requirements can be met by sophisticated sorting and crushing machines or even by manpower alone, but both of these approaches are costly. As discussed above, new plastic pellets are cheap, which is why recycled products cost as much if not more than those made from new materials. Changes in public policy and new technologies are desperately needed to improve the value proposition of recycling commodity plastics for 3D printing.

However, there is one readily available source of recycled material that meets all three criteria: failed prints on both small filament and large format 3D printers. Assuming a single extruder, these failed prints are composed of one material and have a known thermal and chemical history. These parts can be granulated by a machine, such as the Filabot Reclaimer, and reprinted with the pellet extruder on the LF3DP. Nearly all prints on Dr. D-Flo’s LF3DP contain previously printed plastics, which helps lower the cost per kg of a massive print by even more!

Purchase the LF3DP or Components

Dr. D-Flo is excited to announce the sale of both turnkey LF3DP machines and individual components for DIY assembly.

DIY Components:

Components and kits will be available on the new Digital Fabrication Tools store at the beginning of February 2023. Prices are listed on the BOM. To log your interest and to receive priority in purchasing the limited stock of components please email Dr. D-Flo (David) at [email protected]

Turnkey LF3DPγ (Quantity available: 2):

Over the summer of 2023, Dr. D-Flo will hand build two LF3DPγ, which will feature high helix leadscrews for faster travels and print speeds (see versions). Dr. D-Flo will deliver the printers and offer hands on training for both running the instrument as well as optimizing CAD designs and slicer settings for large format printing. Delivers to North America only. Cost: $65,000. Email Dr. D-Flo (David) at [email protected] for more information.

Discussion and Feedback

Do you need more help? The best way to get your questions answered by Dr. D-Flo and other DIYers is to post a question on the forum. Click here for the forum topic specific to this project.

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