The Official ZeGoBeast Manual - Leg Assembly




Welcome to the first entry of the Official ZeGoBeast Instruction Manual!

For those that don't know, ZeGoBeasts are biologically-inspired walking creatures brought to life by you. Inspired by Theo Jansen's leg kinematics, we wanted to create a kit that would teach people about basic kinematics, how to use some basic hand tools, and bring friends and family together through a shared challenge.

We launched a successful Kickstarter for ZeGoBeast in September of 2015 - this guide covers how to assemble the ZeGoBeasts we released as part of that campaign.

In this first part, we'll cover how to assemble the legs, of which there will be 8 total. There's 4 for the left and right sides each, but are otherwise identical to each other.

The second part covers how to assemble the Core.

The third part will cover how to build the Crankshaft and complete the machine.

Let's get started.

Step 1: The Complete Hardware List (v1.0)

Here's a list of all the hardware you will need in the coming sections (not including the wooden pieces):


  • 16x R4-2RS Bearing
  • 40x 685ZZ Bearing
  • 8x 7/8" 10-32 Pan Head Bolt
  • 24x 3/4" 10-32 Pan Head Bolt
  • 32x 10-32 Nylon-Insert Lock Nut


  • 12x 2 1/2" 1/4-20 Hex Bolt
  • 6x 1 1/4" 1/4-20 Hex Bolt
  • 12x 1/4-20 Thin Hex Nut
  • 24x 1/4-20 Serrated-Flange Nut
  • 4x 1/2" 8-32 Pan Head Bolt
  • 4x 8-32 Hex Nut1x 2 1/2" 10-32 Pan Head Bolt
  • 2x Nylon Lock Nut


  • 2x 685ZZ Bearing
  • 24x 1" 1/4-20 Hex Bolt
  • 2x 5/8" 10-32 Pan Head Bolt
  • 50x 1/4-20 Thin Hex Nut
  • 16x 1/4-20 Serrated-Flange
  • 4x 1/4-20 Cap Nuts

Other Hardware:

  • 100x .194"x.375"x.032" Nylon Flat Washer
  • 1x 3lbs Constant Force Spring
  • 8x 11 mm 1" ID Schedule 40 PVC Tube
  • 2x 15.5 mm 1" ID Schedule 40 PVC Tube
  • 2x 13" 1/4-20 Threaded Rod

Step 2: Gather the Parts/Tools

First step: make sure that everything you need is all there.

For each leg, there should be 13 laser-cut components and 18 hardware pieces:

  • Side-Dependent (Labeled R or L)
    • 1x Claw
    • 1x Claw Plate
    • 1x Shoulder
    • 1x Should Plate
    • 1x Upper Arm
    • 1x Lower Arm
  • Universal
    • 1x Parallel
    • 1x Link
    • 5x Struts (not labeled)
  • Hardware
    • 5x Small Bearings (685-ZZ)
    • 2x Large Bearings (R4-2RS)
    • 1x 7/8" Bolt (10-32)
    • 3x 3/4" Bolt (10-32)
    • 4x 10-32 Locknuts (10-32)
    • 9x Nylon Washers (.194"x.375"x.032")

Again, there are 8 legs total, so set aside this quantity for each leg as a set to help yourself get organized.

For tools, this is what we'll need:

  • A hammer
  • A 3/8" hex wrench
  • A #1 Phillips head screwdriver
  • WD-40 (or another oil-based lubricant)

For this part of the manual we'll only be focusing on the L side, but just apply the same steps, but mirrored, for the R side.

Step 3: Shoulder

The first piece you'll be assembling is the Shoulder. This is one of the most important components for providing stability and transferring power from the crankshaft, since it's the only piece that connects to both the Support Rod and one of the Arms.

Step I

First, lay out all of the pieces you'll need:

  • 1x Shoulder
  • 1x Shoulder Plate
  • 2x Struts
  • 1x Large Bearing

Step II

With the lettering facing towards you, push the Large Bearing as far as you into the Shoulder (marked E1) by hand. Once it's seated, use the hammer to pound it flush with the surface of the wood. Make sure that no one side of the bearing is sticking out more than the others.

Step III

Grab one of the Struts and position it over one of the rectangular holes in the Shoulder. These are a tight fit, so you'll need to tap the Strut while positioning it to make sure it's oriented straight up and down. Once you're confident with it staying in place, use the hammer to pound it down the rest of the way. The two flanges sticking out the sides of the Strut should sit flat with the surface of the Shoulder. Repeat with the other hole.

Step IV

Position the Shoulder Plate so that each of the rectangular holes sits just above the Struts on the Shoulder. Tap lightly on each side of the Should Plate above the Struts until it's lightly seated. Then use the hammer to pound the Should Plate into the rest of the Shoulder Assembly, making sure to alternate force between the two sides balance the Should Plate so that it sits flush with the Struts on the other side.

Step 4: Claw

Next, we'll build the Claw. This is the part that actually touches the ground and propels the ZeGoBeast forward. This piece has an extra Plate component to help increase its stability on the ground.

Step I

Layout your components in front of you. You won't need any extra hardware for this one:

  • 1x Claw
  • 1x Claw Plate
  • 3x Struts

Step II

With the lettering facing towards you, gently tap one of the Struts into one of the rectangular holes until it's lightly seated (just like with the Shoulder) using the hammer. Pound the strut the rest of the way until the flanges are flush with the surface. Repeat for the other two Struts

Step III

Grab the Claw Plate and position it so that the rectangular holes are resting on top of the Struts. We'll employ a similar strategy as last time, meaning we should gently tap on all three points above the Struts on the Claw Plate until it's gently seated. Now, to pound it in, we recommend going outside, outside, middle, pushing it in a little more each time. Because of the tendency for this part to skew and tilt when pressing it together, it's very important to balance the forces being applied to it.

Step 5: Assembling A1 + A2 + A3

This is where we actually start getting into the real assembly of the Leg. The way these parts are designed, each of the letters represent a shared point, and the numbers represent their position away from the table. So Z1 gets placed down first, then Z2, then Z3. This way, the only other thing you need to keep track of is R and L parts being on the same side.

Note: For the rest of the leg assembly, make sure all of the lettered sides of the components are facing you as you're building it. This prevent you from building things the opposite way/mirrored from how they're supposed to be.

Step I

Gather your parts:

  • 1x Lower Arm
  • 2x Small Bearing
  • 1x Parallel
  • 1x Large Bearing
  • 1x Claw Assembly
  • 3x Nylon Spacers
  • 1x 7/8" Bolt
  • 1x Lock Nut

Step II

Let's take a Small Bearing and press it into the Lower Arm by hand, then finish the job using a hammer.

Step III

For the Parallel, take both a Large and Small Bearing and press them into the appropriate holes. Use the "lightly seat > pound it in" approach.

Step IV

Take the 7/8" Bolt and push it through the hole marked A1 from the back side (not lettered) to the front (lettered). Next, place one of the Nylon Spacers on the Bolt, followed by the Parallel through the hole marked A2. Place down another Nylon Spacer, followed by the Lower Arm through the hole marked A3. Lastly, place another Nylon Spacer, spray some WD-40 in between each of the plywood pieces along the Bolt, and install the Lock Nut.

Step V

This is the part where patience and feel comes into play. Adjusting the tightness of the Locknut is one of the most important parts of getting your ZeGoBeast to move well. Any one leg with a Lock Nut that is too tight or too lose can affect the feel of the whole machine.

What you're aiming for here is a balance between smoothness and rigidity. When you tighten the nut, you first want to make sure that applying any bending force along the leg is wobble-free. If you can feel the pieces along the Bolt move at all, then it's not tight enough. Once that's achieved, now you can loosen it to the point where each of the components can rotate about the Bolt under their own weight without losing rigidity- that's your benchmark. If you can get this right, you'll save yourself a lot of troubleshooting later.

Step 6: Assembling B1 + B2

Step I

Here are the additional parts you'll need:

  • 2x Small Bearings
  • 1x Link
  • 1x 3/4" Bolt
  • 2x Nylon Spacers

Step II

Take the Link and two Small Bearings - use your hammer to lightly seat, then pound the bearings into the two designated holes. Again, remember to have the writing facing up, away from the table surface.

Step III

Take the Assembly from the previous step, and insert the 3/4" Bolt from the back of the Claw Assembly towards the front through hole B1. Like before, you'll be placing a Nylon Spacer between each of the wood pieces, so insert one here. Next, place the Link using hole B2, and install another Spacer. Finally, spray some WD-40 in between the wood pieces and install the Lock Nut using the same tightness scale as before.

Step 7: Assembling C1 + C2

Step I

  • 1x Claw Assembly
  • 1x Shoulder Assembly
  • 2x Nylon Spacers
  • 1x 3/4" Bolt
  • 1x Lock Nut

Step II

Insert the 3/4" Bolt through the back of the Shoulder Assembly using hole C1. Place a Spacer, then the Claw Assembly using hole C2. Place another Spacer, use WD-40, then tighten a Lock Nut down an appropriate amount.

Step 8: Assembling D1 + D2

Step I

  • 1x Upper Arm
  • 1x Small Bearing
  • 1x Leg Assembly
  • 2x Nylon Spacers
  • 1x 3/4" Bolt
  • 1x Lock Nut

Step II

Install the Small Bearing into the Upper Arm through hole D2 using the same technique as the others.

Step III

Attach the Upper Arm to the rest of the Leg Assembly using the same process as the other pieces - just make sure to use Nylon Spacers between every piece, use a healthy amount of WD-40, and tighten the Lock Nut to a good balance of rigidity and smoothness.

Step 9: Final Touches

Congratulations on building your first piece of a ZeGoBeast!

With this part complete, make sure to check the tightness and smoothness of each of the joints. There should be little to no flex between components, but the whole Assembly should move freely just by waving it around or flicking the individual pieces. Sometimes working the joints a little bit can improve the feel tremendously. If that doesn't work, try adjusting the tightness of the locknuts some more. And, of course, you can always add more lubricant (WD-40).

You'll need to make 7 more of these to have a complete ZeGoBeast, but now that you know how it all goes together, it shouldn't take you too long. Just remember to check that all the relevant parts on an individual leg share the same letter (the Link and the Parallel are the same for both sides), and that you have 4 of each side at the very end.

Thanks, and see you in the next part!



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    2 Discussions


    Reply 3 years ago on Introduction

    Thanks tomatoskins! We'll keep you posted on when the next section is up. In the meantime, we've got some pretty-close-to-final designs up on the Kickstarter page, if you're curious.