instructables

Infinity Cube in Fusion 360

by mjdargen

In nity cubes have become a popular dget gadget. I wanted to design one on my own using Fusion 360 to 3D print inplace. There are several existing designs on Thingiverse; however, they don't provide the design les for customization. Iwill walk you through the creation process and provide the design les and STL les for you to modify and print yourown customized design!

Print-in-place designs can be tricky to perfect. The designs typically use loosely tting joints/hinges with enough of an airgap around them that they move freely, but not enough that they come apart. It can be a tricky line to walk. Sometimesyou might not have enough clearance and your design may fuse together. Other times, you may have too wide of a gapthat it may come apart or it may bridge poorly and become hard to move.

There were a few di erent revisions for this design. At rst, the cubes had a rod that traveled all the way through thehinge. These rods ended up restricting the movement too much and would wear down over time. I then proceeded totry pairs of rounded interlocking pins. Eventually, I determined that creating conical pins and sockets on the hinge andcube would provide the most freedom of movement without sacri cing the strength or durability of the assembly.

A complete walk-through tutorial on creating this design in Fusion 360: https://www.youtube.com/watch?v=UlSd0zvG-_E.

A demo of the cube in action is here: https://www.youtube.com/watch?v=gpM8QhBmqXA.

The design les are also available on Thingiverse: https://www.thingiverse.com/thing:4997903.Supplies:

Fusion 360 (students/educators qualify for free)3D PrinterPLA lament

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Step 1: Designing the Cubes

https://www.youtube.com/watch?v=gpM8QhBmqXA

https://www.youtube.com/watch?v=UlSd0zvG-_E

https://www.instructables.com/ORIG/FD1/PMOE/KUIDRDCH/FD1PMOEKUIDRDCH.f3d

DownloadView in 3D

https://www.instructables.com/ORIG/FQ7/8DH4/KUIDRDCI/FQ78DH4KUIDRDCI.stl

DownloadView in 3D

Create a sketch on the bottom plane (X-Z by default) as shown. Use the two-point rectangle tool to create a 20 mm x 20mm square that begins with the top left corner at the origin. Create a second 20 mm x 20 mm rectangle that is 0.4 mmaway with horizontal lines colinear to the original square. The sketch should now be fully dimensioned.

After nishing the sketch, extrude each of the squares upwards by 20 mm to create two separate cubes. Apply a 3 mmchamfer to all edges of each of the cubes.

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Step 2: Sketching the Hinges

Create a sketch on the top face of the cube placed at the origin. By selecting the top face, Fusion 360 automaticallyprojects the edges of the face into the sketch.

Create a rectangle for the cut area to make space for the hinge. The rectangle should be 10 mm x 7 mm placed 2 mmfrom the side edge of the face and 10 mm from the far edge. Make another rectangle inside the previous rectangle to usefor the hinge extrusion. The rectangle's dimensions should be 9.2 mm x 6.8 mm and it should be o set inside the otherrectangle by 0.4 mm. It will extend over the edge of the cube by 0.2 mm.

Delete the edge of the face that intersects with the squares (between the purple dots) by selecting and hitting the deletekey. This will make the later extrusions easier.

Finish the sketch. Create three more identical sketches for the other hinge connection points. See the animation to see allfour of the hinge connection points.

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Step 3: Cutting/Extruding the Hinges

Select the 10 mm x 7 mm rectangle by selecting the outer "U" shape pro le and the smaller internal rectangle pro le.Perform an extrude cut with a depth of -7 mm.

Next, select the 9.2 mm x 6.8 mm internal rectangle pro le as well as the 0.2 mm rectangle that hangs over the edge.Perform an extrusion with a depth of -6.6 mm.

Finally, select the inside horizontal edges of the hinge facing the cube to apply a 3.3 mm llet. This will round o thehinge entirely and improve clearance and mobility.

Repeat three more times for the other half hinges. Make sure you select "New Body" (not "Join") when doing theextrusions for the hinge. We want to keep each half of the hinge separate to allow us to more easily duplicate/mirror theadditional cubes and hinges.

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Step 4: Creating the Pins/Sockets

Sketching Pins/SocketsSketching Pins/Sockets

Now, it is time to make the pins and sockets to connect the hinges to the cube. View the hinges in the image. In order tomake each hinge, you will need two identical sketches on di erent faces. The sketch should always be made on the facewhere you will extrude the pin from. To make the pin/socket on the right side of the hinge shown in the image, thesketch will need to be created on the face of the hinge. To make the pin/socket on the left side of the hinge shown in theimage, the sketch will need to be created on the inside face of the cube. I standardized by making the pin exit the cubeon the left and the pin exit the hinge on the right when looking at the front face of the half hinge.

Since the sketches will be placed in a 0.4 mm gap, it can be di cult to be sure you are selecting the correct pro les. Youmay have to toggle the bodies on and o to make the pro les visible. When it comes time to make an extrusion or a cut,make sure you have the bodies' visibility turned on.

Start by creating the sketch for the pin/socket on the left side of the hinge. Select the inner face of the hinge hole on thecube for your sketch. Create two center-diameter circles with the same center point. One should be 2.6 mm in diameterand one should be 3.0 mm in diameter. The center point should be a distance of 3.5 mm away from each of the edges.

Next, you will need to make the pin/socket on the right side of the hinge. To do this, create a new sketch on the face ofthe hinge on the opposite side. Use Project/Include to project the center point of the circles from the previous sketchinto this sketch. Then, create two identical 2.6 mm and 3.0 mm center-diameter circles using the projected center point.

Repeat this same process to create the pin and socket pair for the other three half hinges.

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Extruding Pins/SocketsExtruding Pins/Sockets

After completing all of the sketches, it is time to create bodies from the sketches. First, make the extrude cut. Select theouter 3.0 mm ring pro le and the internal 2.6 mm circle pro le. Perform a 3 mm extrude cut at a -25 degree taper angle.Make sure you have the body visible so you can successfully perform the cut! You should now have a conical socket.

Once the hole has been cut, you can do the extrusion for the pin. Select the internal 2.6 mm circle pro le. Perform a 3mm extrusion at a -30 degree taper angle. You should now have a conical pin. Your pin and socket should be nestedinside each other as shown. Ctrl+select the appropriate faces to see through the bodies and double-check.

Now, repeat the cut and extrude process for the pin/socket that protrudes from the cube body. The complete hinge/cubeconnections are shown.

Repeat this same process to create the pins and sockets for the other three hinge halves.

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Step 5: Mirroring/Duplicating Cubes

Finally, the base two cubes and their associated two half hinges are complete. It is time to mirror and duplicate asneeded to create the other 6 cubes.

Start with the cube placed at the origin. Mirror the cube with both of its half hinges. Use the face of the exposed hinge asthe mirror plane.

Now, move on to the second cube. Mirror the cube with both of its half hinges. Again, use the face of the exposed hingeas the mirror plane.

Create an o set plane on the inner face of the two middles cubes. Set the o set for the construction plane to be 0.2 mm.Select the pair of cubes along with their four half hinges. Mirror these bodies across the new construction o set plane.

Finally, select the pair of cubes on the end along with their four half hinges. Select Move/Copy. Use "Free Move". Checkthe "Create a copy" checkbox. Rotate them 180 degrees about the y-axis. Next select "Point-to-Point" on the Move/Copyoptions. Select a point on the face of the hinge on one of the cubes and the corresponding point on the face of the cubewhere you want it to go. It should snap into place. You should now have a completed in nity cube!

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Step 6: (Optional) Customizing Your Design

If you want to customize your design, you can add patterns or letters to the face of the cubes. To do this, create a sketchon the face. Design the pattern within the sketch as a pro le. Once you are nished with the sketch, select the pro le andperform an extrude cut into the face to notch out an area.

If you want to work with text, add text within a sketch. Resizing and manipulating text can be a bit di cult in Fusion 360,so it is easiest to work with a single character per text box to correctly arrange them on the cube faces. Make sure youselect a good font that will have recognizable pro les to cut into the cube face. Once it is in place, right-click on the textand select "Explode Text". This will convert the text into a series of lines and curves. Once you are done, nish the sketch.You can now select the letters as pro les and perform an extrude cut to "engrave" letters on the face.

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Step 7: Printing Your Design

The .STL le was generated with a Z-up con guration. The Fusion 360 The design was optimized to be printed with a 0.2mm layer height and a 0.4 mm nozzle width.

It was designed to be printed with a 10% in ll; however, you can increase the in ll as much as you want if you want thecube to have a bit more weight. 10% in ll is more than su cient to withstand regular use and the occasional drop.

On a Makerbot Replicator+ with default settings, it took about ~2.5 hours to print and required ~30 grams of PLAlament (including a raft). A raft is not necessary; however, our printer is older and has poor adhesion so they were

printed with a raft.

If using Ultimaker Cura to slice your le, be sure to set "Fill Gaps Between Walls" to "Nowhere" under the Wall settings toprevent the hinges/cubes from welding together.

The interlocking pins and sockets should move freely right o the build plate but it will require some working in toloosen up the joints completely, particularly the two hinges that print vertically.

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Step 8: More Projects

For more projects, visit these links:

https://dargen.io/https://github.com/mjdargenhttps://www.instructables.com/member/mjdargen/https://www.buymeaco ee.com/mjdargen

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