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Hexy: Leg Assembly

Hexy will need six legs. This guide explains how to make one of them.

Hexy: Leg Assembly

This guide will bring you through the process of building one of Hexy’s six legs.

The steps of building one of Hexy’s legs are:

  • Gathering the parts and tools.
  • Peeling the protective paper
  • Identifying parts for the subsystems
  • Assembling the subsystems
  • Drilling the holes in the servo horns
  • Attaching the servo horns
  • Attaching the subsystems to the servos
  • Dressing the wires

After you have assembled one of the legs, you will need to build the rest of the six (that’s why they call it a hexapod!). You may want to work together with another person, sharing the assembly tests.

You should expect the leg assembly to take 15 to 25 minutes. The first one may take longer, and the last ones will likely take less time.

The servos are left loose in this assembly, because you will need to center them with the circuit board. When they are centered, you will screw the servo horn securely onto the servo.

Once you have all the legs assembled, you will build the body, and then you will assemble the legs onto the body.

Steps

Step #1:

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  • Gather parts and supplies
  • Parts: One bag of leg parts, three servos, machine screws and nuts, #2 self tapping screws, One long machine screw and nut
  • Tools: Screwdriver, drill bit
  • Optional: plastic dish and cover for hardware sorting and debris storage

Step #2:

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  • Remove parts from bag, sort them by subassembly.
  • Peel the paper off the parts. Use the screwdriver to help with peeling the paper.
  • Place the hardware with the subassemblies.

Step #3:

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  • Place the subassemblies together
  • Put the hardware with each set of parts

Step #4:

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  • Assemble the foot
  • Add the straight side. Place the nut in the captive hole. Thread the screw into the nut.
  • Add the wishbone side. Place the nut in the captive hole. Thread the screw into the nut.
  • Put a machine screw into the hole on the straight side. Thread the nut onto it so 1-2mm of the threads shows beyond the nut.
  • Add the boot.
  • The foot assembly is done.

Step #5:

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  • Assemble the thigh
  • Place two servos into their rectangular holes. The drive end of the servo goes towards the end of the thigh.
  • Place the two H shapes upright between the servos.
  • Put the back side on top of the servos.
  • Place the long machine screw through the assembly and thread a nut onto it.
  • The thigh is now complete.

Step #6:

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  • Assemble the hip
  • Locate the etched circle on each of the end parts.
  • Place the end parts so that the etched circles face each other.
  • Put a nut into one of the captive nut holes on the nut bar. Place the nut bar into one of the ends. Thread a machine screw into the nut.
  • Put a nut into the other captive nut hole on the nut bar. Put the other end piece on, then thread a machine screw onto the nut.
  • Place the servo into the rectangular hole in the hip servo holder so that the drive shaft is in the middle of the piece.
  • Loosen one of the screws holding the ends. Slide the hip servo holder in place so the servo is in the middle of the hip assembly. Tighten the screw to hold it together.

Step #7:

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  • Remove the long, straight servo horns from the bag.
  • You will not be using other parts from the bag, so it's best to leave them sealed up. The screws in the bag are of poor quality, and you don't want them getting mixed up with the other hardware.
  • Using the drill bit, drill the two holes located two holes from the hub on one servo horn.
  • On the other two servo horns, drill the two holes located two holes from the end of the servo horn.

Step #8:

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  • Start the screws into the holes you have drilled in the servo horns.
  • There should be two screws in each servo horn.
  • One should have screws that are two holes from the center hub.
  • Two should have screws that are two holes from the end.

Step #9:

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  • Add the servo horns to the sub assemblies.
  • The cavity in the hub should face in to the center on the foot and on the hip.
  • The third servo horn will be attached to the body of Hexy. Use a self tapping screw to hold this one in place. Start the screw, but don't tighten it.

Step #10:

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  • Insert the servos:
  • Place the drive shaft of the servo into the cavity in the servo horn on the foot.
  • Pivot the foot over until the threads of the machine screw catch on the thigh assembly.
  • Tighten the machine screw with the screwdriver. Press them together slightly to keep the nut from turning. You may also be able to keep the nut from turning with another machine screw.
  • Do the same for the servo that attaches the thigh to the hip.

Step #11:

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  • Dress the servo wires
  • Feed the wires from the servos through the hip assembly.
  • The wire from the foot servo should be fed below the thigh assembly.
  • Feed the wires through the back opening of the hip.

Step #12:

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  • After assembling one leg, you will assemble the whole set of six.
  • Leave the servos loose. In a later guide, you will center the servos and then secure the servo horns to the servos with the #2 screws.

Chris Connors

Making things is the best way to learn about our world.


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