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Step 2: Grip Robot

To create the main shell of the final structure, the second robot, the Grip Robot, attaches to the foundation footprint. Its four rollers clamp on to the upper edge of the structure allowing it to move along the previously printed material, depositing more layers. The nozzle moves dynamically allowing for greater accuracy of material deposition. To create a curved surface the material output will be incrementally offset. Heaters, integrated into the robot’s structure increase the local air temperature to influence the curing process. Controlled by custom software the robot follows a predefined path, but can also adjust its path to correct errors
within the printing process. Rotational actuators control height above the previous layer to maintain a consistent layer.

The Grip Robot size 40*27*12 cm, weighs 4.6kg.

Tools and materials:

-Makerbeam

-Dynamixel ax-12 servos *9

-6mm metal shaft

-Springs

-6mm linear motion

-Waterjet aluminum for body and gears

-Plastic gears -18/6/6mm bearing

-3D printed wheel core

-Rubber to cast wheel and rollers

-Heat gun stripped for heat element, sensors and fans.

-3D printed pulley and belt from hobbycar shop

-4mm acrylic for laser cutting

The print-head positioning system comprises of a front-back linear motion system (11),
side linear motion system (12), front-back motion actuation system (13), side motion actuation system (14) and actuators for print-head or multiple print-heads. The connection of print-heads to the material supply is illustrated in (15). The device positioning system consists of feet (5) each attached to a further four or more legs (4) that are attached to the frame. Legs are connected to the frame via a linear motion system (9). Linear motion bearings (10) allow smooth movement relative to the frame. This motion can be actuated either by springs or by linear actuators (8). Feet are attached to legs via rotary joints that allow rotation relative to the legs. This rotation can be controlled and is actuated by the foot actuation system (7). Wheels (3) are mounted on the feet and are moved using the wheel actuation system (6). The surface is coated with a durable, flexible material to reduce vibration of the device during movement and to increase its grip to the structure on which the device is attached.

In the case the printing path is closed without openings, the movement of the robot is continuous and front-back print-head motion may not be used. The device is placed on the footprint at a desired position, once material is extruded through the aperture of the print-head and the device starts moving in the desired direction, print without pausing is to use one continuous spiral path. In this case the wheels are not in their centralized position during the printing process, the device is constantly moving upwards; every complete rotation the device moves up by the height of one layer.
Having the print-head fixed in a fixed position would cause a number of problems, on any curved path the print-head center would deviate from the center of the path, where the center position of the nozzle is marked with a dashed line. In this case each preceding path would deviate accumulatively from the desired shape thus printing a different structure than programmed.

This can be solved by introducing linear side to side motion to the print-head, it can be used to correct the deviation and control the path of the print head. To position the print-head correctly a mechanical sensor calculates the deviation and adjusts accordingly. If the position of the device and path curvature are known - deviation can be pre calculated geometrically without the need for additional sensors.

If the print-head was confined to only following the previous layer, printed structures could only be shaped as extruded versions of their footprints. This would exclude forms such as vaults, and cantilevers. Shifting the print-head provides an opportunity to alter the curvature of the wall during the printing process. When layers shift relative to their previous layers the curvature of the wall changes. The amount of shift should be precalculated, varying dependent on the position of the device. In the case that the position of the robot is incorrect or an error is detected - curve deviation should be taken into account and either added or subtracted from the shift. The position of the robot in relation to previous layers can be abstracted in various ways, for example different types of sensors from Local Positioning Systems to rotation counters attached on the wheels leading to many possibilities.

<p><em>&quot;Small Robots&quot;?!?</em></p><p>They really are tiny (compared to earth) :)</p>
<p>What is the material that you are using?</p>
<p>Brilliant work! I was hoping it was a more general print bot than the three separate specialized bots, but specialized bots could also be added to accomplish other tasks of construction such as plumbing and conduits for electrical systems. A small &quot;pipebot&quot; could make structural tubing around itself, possibly with a second print head for a rigid foam core. Coordinated little pipebots could make honeycomb cell structures for strength. A fiber placer could also be rigged to insert fibers that stick through and up out of the bead allowing higher strength before the need of the vacuum bot.</p><p>Man does this have my gears turning.</p><p>Thanks!</p>
<p>Brilliant rethinking of 3d printing for large structures!</p><p>The flexibility of these robot's capabilities seem like they would be very impressive, but I find myself wondering if a much cheaper and simpler version could be designed to create simplified housing for disaster areas and other low income communities. I imagine something with a shape like a beehive sort of like the domes created by spirally winding continuous sandbags like these:</p><p><a href="http://www.earthbagbuilding.com/projects/smalldomes.htm" rel="nofollow">http://www.earthbagbuilding.com/projects/smalldome...</a></p><p>The device would not even need much in the way of computing power. The extruder could be guided mechanically, Sort of like this:</p><p><a href="http://jimsoven.blogspot.com/p/the-dome-part-i.html" rel="nofollow">http://jimsoven.blogspot.com/p/the-dome-part-i.htm...</a></p><p></p><p>Of course for this purpose using local materials would be best, but if the polymer/marble dust is cheap enough it would still be practical.</p>
<p>Is this thing DIY? Are there plans available?</p><p>Maybe there is a link here, but I don't see it.</p>
<p>I would like to suggest that, rather than using suction to hold the third (suction) robot in place, you take advantage of the inherent complexity of the structures that the grip robot can lay down, and have it &quot;build in&quot; a track for the suction robot to hold onto and follow. For instance, the grip robot could make a small series of indentations beginning every 0.2 meters horizontally and continuing throughout that horizontal layer. Then it would create an overhang in subsequent horizontal layers. The third (suction) robot would have notched wheels that would fit into this track, holding it to the surface. This would eliminate the need for a complex, failure-prone suction system, and also provide a built-in self-metering (measuring) system that would improve position accuracy. If I'm not being clear please contact me and I'll make a diagram. </p>
<p>that must be quite expensive!! how long did that take?</p>
My brain just melted. Really quite awesome.
This is by far the most incredible and amazing thing ever to come out of instructables. This is so inspiring.
<p>How much for a boat? great ible!</p>
<p>This is really cool. Basically a six-axis 3D printer. I want one.</p>
absolutely awesome! 3D printed house anyone!??
<p>Oh yeah.</p><p>Waste-free construction is the future!</p>
<p>Amazing work. Thank you.<br>And now for something that will make you laugh.</p><p>Your incredible project reminded me of part of a 1974 movie (not very good, except in parts) called The Groove Tube. <br>The part you have to see is this <br><iframe allowfullscreen="" frameborder="0" height="281" src="//www.youtube.com/embed/008BPUdQ1XA" width="500"></iframe></p>
<p>I take it the building material doesn't shrink much, or cracks might form. Rebar, or mesh, or some sort of fiber worked into the material is the usual solution in cement construction. This appears to have none. Do you ever wish it had some back-up fiber worked into the form?</p><p>A really nice instructable. Thanks. </p>
<p>Awesome, but please edit the audio so the &quot;music&quot; is 1/2 the volume. The people speaking have accents (to English speakers) and the obnoxious volume smothers their voices. And those of us who find this amazing would prefer to hear them, not the electronic buzz behind them. </p><p>loved it, I often thought what a hoot it would be to connect a pump/feeder to a fast set plaster/cement kinda like spray on cement. As I have no ability to make that I love that someone else did. </p><p>Bravissimo</p>
<p>I love your 1st paragraph :</p><p>There has always been a close relationship between architecture and technology. However, recently architecture has stagnated and the construction industry has been slow to adopt technologies that are already well established in other fields. Whilst we design digitally we still construct manually.</p><p>Thanks for sharing</p>
That is extremely cool. Except for one picture in which the device is being pushed by someone, it is very hard to understand the size of the objects. A human operator perhaps for proportion in the images?<br>A time lapse video of this project will win the interwebz :)
<p>Just saw the video which was not visible in the instructable app. The process is well thought of and the robots work well. I especially liked the third one which sticks with suction.</p>
<p>Wow, amazing!</p>
<p>I remember seeing this project elsewhere online a while ago. Thanks for posting to Instructables! I love this idea.</p>
<p>Wow, wow, wow... Absolutely amazing. 3d printers are the new future of buildings ,architectures, engineering, industrial, design and art.</p><p>Try contact with NASA, they are working with private corporations on giant 3d printers to settle bases and buildings on planets.</p>
Impressive! And everybody keeps complaining about the ever too small max sizes that 3D printers can spill out. :)
<p>This is so innovative and cool! I'd never thought that tiny 3d printers could be so capable at printing anything bigger than them... Nice job, thanks for sharing!</p>
this is really cool. it's amazing to see everything these 3d printers can do

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