Rotoforge README

This is Rotoforge, a 3D printer that uses continuous friction welding to print metals, plastics and ceramics heterogeneously. If a wire is fed into the contact patch of a wheel which is spinning fast enough and with sufficient torque, the wire will heat up due to friction, and become more flowable(see thixotropy) due to plastic shear(see flow stress and the Zener-Hollomon Parameter).

Under these conditions, even materials like aluminum, copper, steel, glass, and high grade engineering plastics will become extremely fluid (without melting) and bond (given the correct contact and mixing conditions) at the contact patch, in air, without a shield gas!, at relatively low temperatures and pressures. This allows relatively low force, FDM like printing of these materials on a standard 3D printer, given a way to feed wire, and a wheel with adequate speed and torque to keep the material flowing under the chosen RPM and feed rate conditions. This printing process, like forging, can yield material which is stronger as printed, than the initial feedstock.

For example, when printing with Al1100 from full soft wire (yield tensile strength (YTS) ~25 MPa, ultimate tensile strength (UTS) ~90 MPa at 100% elongation) Rotoforge achieves ~90 MPa YTS and ~120 MPa UTS at 33% elongation. a 3.6X and 1.5X improvement respectively at a modest cost in ductility. (approximate equivalent to printing ~H18 temper Al-1100)

Here is what I recommend for getting started with Rotoforge

If you would like to download the part files, schematics and documentation including text assembly tutorials and a getting started guide, clone the repository, or download the zipped folder here on github. We also have a youtube channel and a read the docs page.

If you want regular updates on progress from Michael, he has a blog he updates periodically.

For more active discussions we have a discord channel and a subreddit.

for proper data storage on feeds and speeds and other printing and deposition parameters as well as in process data storage we have a zenodo repository:

and we are occasionally active on the GOSH community forums:

Files

Included in this Rotoforge repository are: a bill of materials,for sourcing your own parts,

guidelines for contributing for those looking to be part of the community, and Documentation files to get the new user/developer started and provide some basic guidance for troubleshooting.

Source files, including complete CAD data for the mechanical parts, and electronics and source code to build and operate your own Rotoforge on an Ender 3 motion platform. Principally rotoforge can be built on any motion platform, and more rigidity is better, but not strictly neccessary. Also a small cache of untested desgins in the works by other developers.

Mechanical Parts

Rotoforge is currently just a mechanical and electronics attachment for an FDM printer which enables continuous friction welding as the new mode of energy injection and material deposition. the original mechanical CAD files are native to Fusion360. I intend to provide OpenSCAD or similar fully open source versions in the future.

Electronic parts

Rotoforge electronics are modeled in KiCAD and EaglePCB. There are off the shelf versions available as well that do the job. Mostly you will need: In the US: a 110->240 volt step up transformer. a Variac or other method to control the speed of the flex shaft grinder (not required but useful). A >800 watt flex shaft grinder(sometimes called a "rotary tool" or "flexshaft die grinder").

Software

There is presently only simple demo software for Rotoforge, as it runs on the motion control code and firmware of a typical FDM machine. All you will need to do to start exploring is install the mechanical and electronic parts, and use your slicer of choice (or use my provided python g-code generator) to adjust your feeds and speeds to suit the requirements of printing metals, plastics and potentially ceramics of your choice. There is currently very little information in the wild on what feeds and speeds will work so this is a big point of ongoing exploration and where almost anyone could help!

The Future

The printer only drives in straight lines in -X direction (it has to reset after every line to build thickness in Z) and can print while drifting at up to ~+-30 degree angles in the direction right now. Typical deposition rates are 4-12 mm^3/s in this mode. But soon with the addition of a 4th axis and closed loop spindle and deposition temperature controls we will be printing ironclad boats, rocket, and car engines, robot, bicycle and car parts, at 2-4X faster in strong aluminum, copper, steel, and with your help beyond!

Rotoforge software is licensed under the AGPL-V3

Rotoforge hardware is licensed under the CERN Open Hardware License-strong

There is a video assembly guide for this printer modification here There are ongoing blogs and technical details on development of the hardware, physics and materials science involved in this project here

Safety

This printer mod is LOUD and can create high speed flying debris (the wheel at full speed stores as much energy as a .357 magnum bullet). Wear eye/face/body/ear protection while the printer is in operation. If you choose not to do this, I would recommend enclosing the printer to protect you and your property and family. If you choose to operate the printer without these safety measures, you do so at your own risk.