SALEM - Construction 3D Printing

Suspended Additive Layer Extrusion Manufacturing - 3D Printing extremely large multi-storey structures.

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SALEM is a 3D printing manufacturing concept, predominantly aimed at construction, that utilises a cable suspended Extruder and a modular, adjustable structure which enables the print envelope to be customised to the needs of the given construction project.

The printer features an Extruder for printing the cement, 8 Hoists for suspending and controlling the location of the Extruder; and a 4-legged support structure to provide the variable Hoists with a fixed axis. The Extruder is connected to all 8 Hoists via cables and cement is fed to the Extruder via a Tank and Pump system located on the ground. The printer would be capable of printing any aggregate/cement mixture that can be pumped, enabling structures to be built on, for example, Mars without construction materials brought from Earth.

Construction 3D Printing

SALEM is a form of Construction 3D printing, a relatively new method of Additive Manufacturing aimed at producing large objects for construction purposes. The general principle of Construction 3D Printing (C3DP) is the same as that of its much smaller desktop counterpart. A desired article for manufacture is designed using CAD software and is “spliced” into consecutive layers from the bottom of the model to the top using special software. These layers are then converted into manufacture instructions that tell the printer how to operate to reproduce that layer. The 3D printer then manufactures the desired article by printing out the model layer by layer according to the manufacturing instruction file (often referred to as a GCODE).

The materials printed by C3DP machines are typically cement or metals and the printers come in many shapes and varieties. These include rotary arms, robotic printers and overhead cranes to name a few styles. One of the best examples of current C3DP technology is a rotary arm printer designed by Apis Cor (see below).

Apis Cor 3D Printed Demo home

Current C3DP Issues

One of the key issues with current C3DP machines is scalability. To print a larger structure, you generally need to build a larger printer which is more expensive and limits the ease of assembly or deployment of the printer. The Apis Cor printer for example, can only print within a circular envelope as wide as the print arms reach (about 8.5m).

Some C3DP companies, such as the Chinese company WinSun, have approached this issue by completing their prints in segments at a central location, then assembling the segments at location. There are two main issues with this solution. The first is that it requires transport of the segments to the final build location. This is cumbersome for large structures and prohibitive for building structures in uninhabited regions without transport infrastructure like roads and where it is difficult to erect craneage to lift and place the segments.

WinSun Printer in operation

The second issue is that structures built in segments are inherently less structurally sound than a structure printed in one constant extrusion.

How SALEM works

SALEM works by triangulating the position of the Extruder based on the extension length of the Hoist cables and the relative positions of each Hoist. The Hoists can traverse the length of the Support Structure and will rise gradually as more layers are added to the printed cement structure. The Hoists can extend or retract the cables and by extending some cables and retracting others, it is possible to move the relative position of the Extruder in a fully controlled manner. This allows the Printer to print any shape within a 3-dimensional print envelope. The Printer could be capable of printing with millimetre accuracy once fully developed and will be capable of printing far more complex structures than current construction methods feasibly allow.

Each of the Supporting legs are composed of several standardised pieces. By adding or subtracting these grid pieces from the support the height of the printer can be adjusted. It is permissible to secure these Support Legs at any practical length apart, from as little as 2 meters separation, to upwards of 100 meters. When erecting the printer there are several calibration operations which set the starting positions of the Hoists, Support Legs and Extruder as well as identifies ground height and slope of the print envelope. This means that it is unnecessary to position the legs perfectly square as the print envelope is entirely relative.


Benefits of Construction 3D Printing

There are several benefits to construction 3D printing that have already been proven by many of the current C3D printers in development. The main benefits are:

  1. Cost – C3DP reduces the cost of building structures by minimising waste and significantly reducing the number of manufacturing steps...
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SALEM Proposal.pdf

The long form proposal for the SALEM 3D Printing concept

Adobe Portable Document Format - 4.97 MB - 05/14/2020 at 00:05


x-zip-compressed - 1.18 MB - 06/01/2020 at 20:33


Extruder holder V2.stl

Standard Tesselated Geometry - 648.81 kB - 06/01/2020 at 20:34


Cable clip.stl

Standard Tesselated Geometry - 3.85 MB - 06/01/2020 at 20:34



The arduino end of the code. This reads the processing 3 signals and controls the 16 motors of the desktop prototype

ino - 5.58 kB - 05/14/2020 at 00:03


View all 13 files

  • 8 × Spool Desktop prototype Hoist Spool. 3D printed
  • 8 × Spool Gear Gear that marries to the Spool Motor and the Spool for the Desktop Prototype Hoist. 3D printed
  • 128 × 2mm dia neo magnets Embed in the Spool gears and track gears to trigger hall effect sensors
  • 24 × A1344 Hall Effect Sensors Measures how much the track gears and spool gears have turned for a secondary absolute measurement(not yet coded)
  • 8 × Right Track Gear Cover Part 1 covers the track gear and contains A1344 sensors

View all 42 components

  • Key SALEM considerations for ​CalEarth

    jon.knutton08/07/2020 at 23:44 0 comments

    This Log is to better highlight the main considerations, advantages and adaptations applicable to SALEM for the CalEarth humanitarian foundation.

    There are currently around 1.6 billion people who do not have adequette access to shelter and 1.9 billion who are considered severely food insecure. This is the fundamental driving force for why SALEM exists and why it is open source. In modern society no one should have to go to sleep hungry and without a roof over their head. it's unnacceptable and deeply troubling that humanity could achieve such monumental feats of engineering and technological progress and yet still allow 1/5 of its people to go without the most basic of needs.

    When fully realised SALEM will allow for the cheap, rapid and labour light construction of structures of virtually any size in some of the hardest to reach locations on the planet and beyond. 

    One of the key design requirements of the printer was that it would be compactable, modular and for each subassembly to weigh no more than the manual handling limit of a two person lift. It was also designed to need no heavy machinery to be assembled. This is to ensure that it could be used to service the housing needs of individuals that do not have the benefit of a fully infrastructured environment, making it an ideal concept for use in humanitarian missions.

    The setup process of the printer demands no prior knowledge of architectural or engineering principles and is simple and easy to learn and teach with no technical steps (beyond basic computer knowledge) or requirement for careful accuracy (see section 2.7.0 of the proposal for a step by step detail). The print envelope is entirely relative and does not require a set up that is perfectly square or a ground that is levelled to any great degree. Calibration steps can be integrated into the software to automatically calculate the shape, area and ground slope/displacement to remove virtually all need for accuracy in setup and preperation. 

    The printer was also designed with the intention of printing with materials that can be readily found on site. For humanitarian efforts in arid regions, this could be as simple as a soil slurry. For wetter and seismically active regions clay can be refined on site out of the surrounding soil using a basic old method called wet clay harvesting. When the clay slurry has been extruded and has dried, a fire can be lit inside the structure to cure it for a long lasting weather resistant finish. To improve the structural integrity of the prints the soil/clay slurry could also be mixed with a small amount of lime or cement (2-10%)

    Construction 3D Printing naturally lends itself to the architectural ethos of CalEarth of utilising the power of the curve to produce stronger structures as this form negates the need for pausing the print to fit lintels and other supports. 

    As SALEM was designed with the intention of use for applications both small and very large it is also possible to set up the printer once for a large print envolope and produce multiple habitats in one print in much the same way you would stack multiple components onto one print with desktop 3D Printers to save time. This means that the build crew can be very small. needing only an initial crew of two people to assemble the printer and then one to feed additional building mix into the mixing tank as required.

    One pain point of this solution for humanitarian work is that there is a labour cost associated with creating the slurry. It is not expected that in the earliest versions of SALEM that the printer will be well enough engineered to manage large stones or other big impurities in the slurry consistency meaning the soil to be used will need to be siphted before being mixed with water and cement/lime in the mixing tank.

    For this reason, this technology would be most beneficial in proactive humanitarian missions wherein the community can prepare the soil or clay mix ahead of the printers arrival as opposed to producing...

    Read more »

  • Building the technology of the future

    jon.knutton07/13/2020 at 11:44 0 comments

    This is a promo video that explains what SALEM was designed for and what I am all about. Please take a few minutes to watch and if you like the message, share it out!

  • New Printer Animation

    jon.knutton06/12/2020 at 14:25 0 comments

    I wanted to give a better representation of how the printer might look when in operation with an actual construction print, so I created a short animation.

    Apologies for the terrible rendering, this is the first thing Ive ever animated.

  • This is a 100% Open Source Concept

    jon.knutton06/01/2020 at 22:28 0 comments

    I have been working on this project for about 2 years now and have spent perhaps 2000 hours so far developing it. My goal is to either find investment to move onto the second of 4 phases of development (details in the proposal in the files section) or to put this in front of companies or individuals that could adopt the technology and continue development. What is ultimately important to me is that this idea is used, so I have chosen to make it 100% free and open source for anyone and everyone to replicate (including for profit) if they wish. 

    I am currently patent pending (see files) so please contact me if you are intending to use this idea and would like written permission for legal reasons. If you would like to help me to continue my own development of this concept please get in touch at or send me a message on my site Cloud Beacon.

    I am a Project Manager and Aerospace Engineer by trade. In my last role (which I left in sept last year to pursue this) I was responsible for managing a portfolio of $1-200M worth of Experimental TurboFan Jet Turbine projects

View all 4 project logs

  • 1
    Print Desktop prototype parts

    This is an instruction manual for building a Desktop prototype version of the SALEM printer. SALEM has been designed specifically for construction 3D Printing applications so this desktop version is for demonstration purposes only and does not function as an actual 3D Printer (not accurate enough). It is however a fun project for all hackers and 3D Printing enthusiasts to complete and is in early stages of development so has lots of opportunity for improvement (especially on the software side).

    The first step to building one of these printers for yourself is to print out all the custom parts. The files for this can be found in the "Files" tab of this project. Components that are tagged "3D Printed" in the "components" section need printing with a suitable SLA printer.

    You will need approx 3 litres of epoxy resin to complete the full components print.

View all instructions

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