Tapsterbot 2.0: Servo-Arm Assembly

Introduction: Tapsterbot 2.0: Servo-Arm Assembly

The Tapsterbot 2.0 is an open-source deltabot, which aims to help the testing of mobile applications on real devices (iOS, Android, etc), but which could serve as an excellent introduction to robotics and Arduino.

Here, we'll assemble 3 identical Servo-Arm components. We'll show step-by-step how to create the first one, then you will repeat these steps on the remaining 2 components. When assembled, they should look roughly like the picture above (your colors may vary).

The parts list here is for 1 component: you'll need 3x of everything to make all three

For each component you will need (in approximate order):

  • 1 Hitec HS-311 servo (clockwise rotation) - see BOM for details
  • 1 2-blade propeller shaped servo horn (the white part that fits on the servo shaft; it should be included with servo kit)
  • 1 Screw for attaching servo horn to shaft (should be included in servo kit)
  • 1 Servo mount
  • 2 6-32 Socket Head Cap Screws
  • 2 6-32 Hex Nuts
  • 1 9x1 beam
  • 1 Servo-Arm with embedded magnets (from Arm Assembly Instructable)
  • 2 Small screws from servo set, to fit in the small holes on the horn
  • 2 10-32 3/4 in Socket Head Cap Screws
  • 2 10-32 Undersized Machine Screw Hex Nut

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Step 1: Attach Horn to Servo

The important thing in this step is to get the servo rotated in the correct position, and to attach the horn to the servo so that it sits at the correct angle

  1. Hold the servo so that the logo is on your right, as indicated in the picture
  2. Rotate the servo shaft counter-clockwise, until it reaches its limit
  3. Attach the horn to the servo shaft, attempting as much as possible to achieve an "ascending" angle to the center-line of the servo. It should roughly follow the pink line in the above picture

Note: you will likely not get the angle to be exact. This can be corrected to a large degree within the software calibration, so don't worry too much about it

  1. Ensure the servo is rotated to its limit counter-clockwise, and that when it's at its limit, the centerline of the horn is at the correct angle
  2. Screw the horn in place

Step 2: Attach the Servo to the Servo Mount

This step will attach the servo mount to the servo itself

  1. Insert the servo into open side of the C-shaped servo mount. Ensure that the HiTec logo is on your right as you are looking at the servo, and that, in this orientation, the servo mount envelopes the "top" of the servo
  2. The 2 arms of the servo mount feature slightly smaller holes than the back. These 2 holes should line up with the two upper holes on either side of the servo
  3. Put a 10-32 screw through each of the upper holes of the servo, and use a 10-32 nut to secure the mount in place. Do not over-tighten
  4. When complete, the mechanism should look like the 3rd picture above

Note: I used clear plastic for this servo mount so the orientation and contrast can be seen easily. The final robot in my case will be all black

Step 3: Attach the 9x1 Beam

This beam is what connects the mounted servo to the top part of the larger robot assembly. The 2 screws pictured will secure the beam to the servo mount. 2 additional screws will come in from the top, through the outer-most holes in the beam, securing all components in place

  1. Hold the servo in front of you, HiTec label to the right as usual
  2. Place the 9x1 beam in front of the servo mount
  3. Line up 2 socket cap screws in the holes of each side of the beam (the holes leave some margin on either side, to allow for the screw coming in through the top)
  4. Holding a nut behind the corresponding hole in the servo mount, screw the parts together until they are snug. Do not over-tighten

Step 4: Attach the Servo-Arms

The pictures show the component with the mount and beams removed. This is to show a clearer picture of the process--it is recommended that you follow the steps in the given order.

  1. Take the "upper" Servo-Arms from the previous Instructable, and orient them so that the small holes in the sides line up with the holes in the servo horn
  2. Ensure that the tapered side of the Servo-Arm is facing outward from the servo
  3. The longer side of the Servo-Arm should follow the longer side of the servo (i.e. it should cover up the HiTec logo, and extend a couple centimeters to the beyond the servo case)
  4. Orientation in this step is a frequent and easy mistake to make. Better pictures will follow
  5. Using the 2 screws from the servo kid, screw the arm in place, such that the screws go through the center hole of each propeller blade (there should be 3 holes total on each blade)

At the end of this step, ensure once again that the angle of the Servo-Arm is slightly "ascending" when the HiTec logo is on your right, and that its range of motion is from this angle downwards

Step 5: Attach the Arduino to the Arduino Plate

For this step, you'll need:

4x 4-40 screws

4x 4-40 hex nuts

1 Arduino Plate

1 Arduino (not that the board pictured is different, but 100% compatible with, the Arduino listed in the BOM)

  1. Line up the Arduino board so that the holes in the board line up with the small holes in the Arduino Plate
  2. Thread 1 4-40 screw through each hole in the Arduino board, ensuring they go through the corresponding hole in the Plate
  3. Attach the hex nuts as pictured. Do not over-tighten

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    5 Discussions


    5 years ago on Introduction

    This looks pretty cool. What exactly are you building here?


    Reply 5 years ago on Introduction

    Sorry, I know I'm posting it backwards... it's a long story :)

    The main idea is in the link below. It's not my creation, it's a robot created by Jason Huggins, to help with the automated testing/tapping of mobile applications.


    To me, though, it might serve better as an all-purpose deltabot design that is completely open source. It could conceivably hold a pen, draw pictures, do Spirograph... whatever you want.

    For me personally it's an educational tool to help me and my children learn how to manipulate real-world objects using a combination of hardware and software. I thought it would be a good idea, while I'm at it, to go ahead and share the instructions with the rest of the world.


    Reply 5 years ago

    That's really helpful to know. Maybe it might be worth saying a bit more about this in the main body of your ible so that people like me (that know nothing about robotics) know what it is you are doing.


    Reply 5 years ago on Introduction

    Right--this is where I'm new to the ible world :). I'm trying to create a Collection that will group all these sets of steps together, but it says I need 5 ibles before I'm able to publish my collection.

    Do you think I should wait until I have 5 (and a collection) before I even publish any of them?


    Reply 5 years ago on Introduction

    Hey Maestro,

    Even if you do post as a collection, the individual 'ibles will show up as they are published, in searches, and on your profile. So it's a good idea to explain a little bit about the overall project and include links to the other parts of your collection. Welcome to Instructables!