3D Printing with a Robot Arm [video] | Hacker News Reader

3D Printing with a Robot Arm [video]

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20 pointslaktak18 comments

This sounds cool, but I'm annoyed that the video is mostly shots of the creator of this setup talking about it, with relatively few shots of the printing process in action, or the end result, or comparisons between the end result and a conventional setup.

The non-planar structure, and the tilt of the head being normal to the surface is meant to produce a stronger result, so let's see how much stronger it is! The first layers are planar but layers in the center are able to vary more in height, so show more footage of it during one of those later layers.

This felt more or less like watching someone speak out loud the abstract for the paper he's writing about it.

Agree. Non planar 3d printing has been worked on for some time https://www.youtube.com/watch?v=XKVyBa8J3eQ . I like the fact of having a precise 6-axis arm that could combine additive, subtractive manufacturing. In addition I was also wondering if it would make sense to have a fixed nozzle and the arm is moving the plate. This would increase the printing angles and allow for very flexible shapes.

From the video: the biggest advantage of using a 6 axis robotic arm is that the nozzle can be pointed in any orientation. This allows you to design and print along 3d curves which make stronger parts.

Traditional 3d printers stack 2d planes on top of each other, which make for strong layers but weak layer-to-layer connections. This is OK for some parts but not all. Another downside is things like holes - vertical holes can be pretty accurate and strong, but horizontal holes are not (since the curve is made by different layers).

I wonder if this could be simplified to have a traditional 3 axis gantry style 3d printer with a nozzle which could rotate on one or two axes? It wouldn't have the full range of motion that a robotic arm does, but it might be "good enough"? A Bowden drive could help reduce the mass of the extruder making it a little more feasible.

For those wondering about the accuracy of these arms, you may find this quite interesting - https://en.wikipedia.org/wiki/Strain_wave_gearing

These gearboxes are becoming quite inexpensive for hobby CNC applications - e.g. rotary 4th axis or trunnion 5th axis setups. The precision is quite good for relatively low cost.

I doubted at first that 6 axis arm can have enough accuracy for .4mm hot-end. After all with 'planar' 3D printing even vibrations within the chassis will affect print quality. However, apparently there are arms with 0.005mm repeatability and zero backlash.

https://www.mecademic.com/en/meca500-robot-arm

This is cool. However, Universal robots (in the video) sells collaborative robots which usually have lower repeatability than industrial arms.

This is cool as shows the level of control is getting there to the stage that my dream of having a robot soldering arm to do all those ever decreasing component sizes is becoming more cost viable.

I’d love for a robot arm to become a linux level open source project.

I think the level of innovation around it would explode. Companies would pop up for cheaper prosthetics and manufacturing engineering.

I think you can have that. you can buy a robot arm, hook the servos or steppers to LinuxCNC, and control it directly through there. If you do this, look for an arm made with Harmonic drives for the best control.

Probably not exactly what you had in mind, but the AR3 from Annin Robotics is open source.

https://www.anninrobotics.com/

The Rotrics DexArm [1] supports 3D printing, laser engraving, and other functions with quick-change end-effectors. Their Kickstarter delivered the desktop robot arm last summer; now they also sell through Amazon. The 3D printing volume is "bigger than 220 x 220 x 270 mm (8.6 x 8.6 x 14.9 inch)." I have printed dimensionally sensitive models such as Raspberry Pi enclosures.

[1] https://www.rotrics.com/

This could be the way to go for 3d printing houses. Instead of setting up a coordinate system on the build site you just show up with a truck with this arm attached.

This is already used for large-scale construction, e.g. a 3D-printed bridge [1] was made using an industrial robot which wielded a MIG-welder fed with stainless steel thread.

This system still uses chopped fibre in a plastic base, I wonder what the results would be with directed longer fibre which is laid down in the stress direction. This would necessitate a fibre cutter - a laser cutter would be the most flexible - in front of the print head so it would complicate the design but the resulting artefact would be much stronger. Such a longitudinal fibre printing head could be part of an assembly with different print heads in a revolver assembly like shown in this video.

[1] https://mx3d.com/industries/infrastructure/mx3d-bridge/

Haha, I'm in this cycle. I can go a long time wondering what the point of 3d-printing is. Then I see that bridge and I'm back at: wow, I want that too!

Here’s an example from industry: https://youtu.be/_deslc68RMw

They print a mold using water soluble filament, use the same arm for carbon fiber placement, and then rinse out the support after curing. Very useful for CF parts with complex geometry, primarily used in aerospace applications.

I wonder what kind of placement accuracy that arm gets, both relative and absolute? Seems like that arm is doing better than I would expect for the size/weight of the actuators. Not something you'd be able to do without an extremely expensive arm.

If you use harmonic gear boxes and reasonably nice servos you could build this arm with a moderate quality machine shop to support the weight of the print head. I'd say that glued on aluminum lugs and precast CF tubes would get you pretty far.

to me, the big benefit of something like this is that you could reasonably run 7axis - Arm is 5 axis, but then add tilt/swivel to the bed. it would allow you to choose in which direction you were building. I don't think any of the standard slicers for cheap 3d printers can do that stuff yet, but maybe eventually CAM packages will be able to support more modes of additive manufacture.

that said, for large parts this would maybe be worthwhile. For smaller complex parts, the powder bed approach for the HP multi jet fusion printers (an example) is still nicer than this because it keeps the part fully supported during the whole print so you don't need to worry about slump.

What’s really cool about this is it could enable multiple print heads working in parallel.

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