[nexus_dan]

Hello all,
I’m interested in experimenting with nonplanar 3D printing using a 6DOF arm; I’m curious if anyone has installed a printhead as the end effector on Thor (it’s my primary arm candidate for this project). If so, does anyone know of existing builds? All I can find online for robotic arm 3D printers is either much, much larger scale, or I’ve also seen a few discontinued/experimental 4DOF desktop arm printers. But 6DOF really opens up a lot for this application. Any similar projects you could point too would be of interest as well.
Thanks for any help you can offer –

[Angel LM]

Hello Nexus!

I have not seen anyone using Thor for 3D printing yet. If you are going down that road, let me warn you of a couple of things that can go wrong if you use this robot.
The control firmware used for this robot is a modified version of GRBL. GRBL is a firmware designed for CNC machining machines, not for 3D printing, so you would need to adapt a 3D printing firmware (e.g. Marlin) to work with Thor’s configuration.
On the other hand, trajectory generation would be a problem.
Currently the programming of Thor’s movements are manual. I have not developed any specific trajectory generation software for Thor and I do not know if there is any that can be adapted to this robot.
Even now, with GRBL I have complications to make straight lines with the robot, since the GRBL configuration allows me to configure the motors to start and end their movement at the same time, or for each of them to do it at the indicated speed, but so far I have not been able to ensure that you can make movements in a straight line only by entering a starting point and an end point.

In short, you could use Thor to 3D print, but I think only the mechanics and electronics. But you would have to develop the control and trajectory generation part yourself.

Obviously, if you decide to take the step, I’ll be happy to give you a hand if you need it!

[nexus_dan]

Thanks for the reply Angel! I guess I do not know enough about firmware programming to do this myself, but it seems possible given that some companies and universities are doing this on a large scale. At a high level, if GRBL can be used for subtractive manufacturing toolpaths, couldn’t it also be used for following additive manufacturing toolpaths? Of course you would need to add an “extrusion” axis and “extruder temp” control for 3DP… but I’ve read about GRBL being used for 4-axis and 5-axis CNC machines so maybe that is possible. At basis it seems simple: slicer generates toolpath/extrusion parameters –> GRBL interprets toolpath instructions into servo kinematics –> servos move based on kinematic instructions. This should be the same for additive as it would be for subtractive manufacturing, no? I know there’s probably something I’m missing because my understanding is still surface level.

[Angel LM]

It may be possible to use GRBL to additive process, but as I have no experience doing that I can´t ensure it… I remember that someone made a Marlin Version for Thor in the past (Marlin is a common firmware used for 3D printing). But I can´t remember who did it…

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