Spherical Parallel Manipulator

When you think of robotics, the image of high-tech machinery powered by motors and servos might come to mind. But what if I told you there's a way to create complex robotic movements without a single motor? Non-motorized spherical parallel manipulators (SPMs) use only passive components—simple dowels, strings, and clever linkages—to move a platform in any direction, proving that art and science can collide in unexpected ways.

At its core, a non-motorized SPM is a perfect marriage of mechanical simplicity and engineering creativity. There’s something almost poetic about the way such a system functions, transforming basic materials into a finely-tuned machine that moves with elegance and precision. It’s like building a kinetic sculpture, where every piece plays its part to create fluid motion, showcasing the beauty of physics in action. No motors, no electronics—just pure mechanical ingenuity. It’s not just a feat of engineering, it’s art in motion.

3D Printed Parts:

1. All spherical parallel manipulator (SPM) parts have been 3D printed. You’ll need access to:
2. 3D Printer
3. Filament of your choice (e.g., PLA, ABS, PETG)

Purchased Components:

1. Bearings:
2. 6004 2RS Bearings – 3 pieces (42mm outer diameter, 20mm inner diameter, 12mm thickness)
3. 608 2RS Bearings – 6 pieces (22mm outer diameter, 8mm inner diameter, 7mm thickness)
4. Screws:
5. M6 x 60 mm Bolt Set – 1 set (includes M6 nuts and washers)
6. M5 x 25 mm Bolt Set – 6 sets (includes M5 nuts and washers)
7. Auxiliary parts:
8. Rubber Feet – 4 pieces

Begin by 3D printing all the necessary components for the spherical parallel manipulator. You can select the material, color, and finish according to your preference. Remember that you’ll need 3 identical Arms(x3), while the rest of the parts will require just a single print each.

Once your parts are printed, grab the 6004 bearings and press-fit them into the designated slots on each of the three arms (Arm 1, Arm 2, and Arm 3). Next, take the 608 bearings and press-fit them into the tip joints of the arms and also into the slots on the Center Platform. Ensure that they are snug and rotate smoothly.

Now, it's time to assemble the arms with their respective shafts:

1. Take Base with Shaft 1 and press-fit it into the inner race of the bearing on Arm 1.
2. Repeat the process for Shaft 2 with Arm 2, and Shaft 3 with Arm 3.

Ensure all shafts fit securely into the inner race of the bearings on their respective arms. You can add the rubber feet on the bottom of the base.

With the arms and shafts prepared, it’s time to stack them. Follow these steps:

1. Start by placing Arm 2 on top of Arm 1 (which is connected to the base).
2. Next, stack Arm 3 on top of Arm 2.
3. Use the End Plate and secure everything by tightening it with the M6 x 60 bolt, nut, and washer. This will lock the arms into place.

Now, connect the three identical linkages to the tip joints of the assembled arms. Use the M5 nuts, bolts, and washers to fasten them. Be sure to check that the linkages rotate freely; if they are too tight, add washers as spacers to prevent binding and allow smooth movement of the bearings.

Next, align the Center Platform and attach it to the three linkages in the same manner, using the M5 nuts, bolts, and washers. If needed, use a hot air blower to slightly warm and adjust the linkages, ensuring the platform aligns perfectly with your reference ground for smooth operation.

Finally, take the Pin and press-fit it into the center of the platform. This pin will act as the primary rotational axis for the spherical parallel manipulator, completing the assembly.