WidowX Robot Turret Assembly Guide
for RX-24 & RX-28 Dynamixel Servos

Tools Needed

  • 1/16 Hex Wrench (included)
  • 5/64 Hex Wrench (included)
  • 1.5m Hex Wrench (included)
  • 2m Hex Wrench (included)
  • Small Flat Head Screw Driver
  • Wire Cutters / Strippers

Parts List
Note: Some of the parts in some assemblies come packaged in seperate smaller bags because they come with a bracket or other various part. Please review the entire parts list to ensure you have all necessary components. Some kits will have spare bolts, nuts, or screws included.

4 X 4 X 1 X 8 X
20 X 8 X 8 X 3 X
4 X 4 X 4 X 4 X
2 X 12 X 1 X

STEP 1 - Peel off the masking tape
Peel the masking tape off the ABS pieces.

STEP 2 - Attach the rubber feet
Attach the rubber feet as shown or as desired onto the legs of the "X" shaped bottom base.

12 x

STEP 3 - Mount the arbotiX to the bottom base
Attach the four 4-40 x 3/8" PCB standoffs to the arbotiX as shown using four 4-40 1/4" button head bolts.

4 x 4 x
Attach the four 4-40 x 3/8" PCB standoffs to the base as shown using four 4-40 3/8" button head bolts.

The orientation of the arbotiX to the base does not really matter.

4 x

ASSEMBLY TIPS: Using Turbo Lock

STEP 4 - Identifying your Tilt & Pan Servos
One of your servo boxes will be labeled with a sticker identifying the Tilt Servo. Be sure to not reverse the servos during assembly. The servos come preprogrammed with IDs to identify to the controller which one is Pan and which one is Tilt.

STEP 5 - Mount the Tilt Servo Horn and Hub
The servo shaft has positional markers, a grove on the tip and a hole on the side. Make sure these are aligned pointing strait up and centered. The single dot marker on the Horn will line up with these.

Mount the Tilt Servo Hub. Ensure that the hub marker is aligned exactly center top. The center hole of the outer mounting holes should be perfectly aligned top to bottom.

1 x
Mount the passive hub on the back of the Tilt Servo using a Hex Socket Head M2.5 x 8mm bolt.

1 x

STEP 6 - Mount the Pan Servo Horn
The servo shaft has positional markers, a grove on the tip and a hole on the side. Make sure these are aligned pointing strait up and centered.

First place the thrust washer on the Pan Servo Hub before mounting. The black side faces in toward the servo.

Note that we mount the Pan Servo Hub in an offset position. The hub marker is aligned one notch of the shaft spline counter-clockwise. This will make the outer mounting holes shift over by one as shown in the picture.
1 x
NOTE: Video shows mounting without the thrust bearing for demonstration.

STEP 7 - Mount the Pan Servo back frame
Mount the Pan servo back frame as shown using four Hex Socket Head M2.5 x 6mm bolts

4 x
Frame OF-RX28B Mounted on the Pan Servo

STEP 8 - Mount the Tilt Servo to the Pan Servo Horn
Mount the Frame OF-RX28S as shown on the Pan Servo Horn using eight Hex Socket Head M2 x 3mm bolts.

(You can now see why we offset the servo horn to align this bracket.)

8 x
Seat four M2.5 Steel Nutes into the nut sockets on the bottom of the Tilt Servo.

4 x
Ensure that the drive horn is oriented on the right as shown. Attach the bottom of the Tilt Servo to the Frame OF-RX28S using four Hex Socket Head M2.5 x 6mm bolts.

4 x

STEP 9 - Mount Frame OF-RX28H and Mounting Plate
Attach the mounting plate (if being used) to the Frame OF-RX28H as shown using four Hex Socket Head M2 x 8mm bolts.

4 x
Top View.

The mounting plate is provided as a blank plate for customers to drill or cut as needed for their projects. It is an optional piece that some may choose not to use.

If you do not use it a good way to discard it is to tie a string through one of the holes and give it to a family member that you don't particularly like and call it "A robot Christmas tree ornament."
Attach the Frame OF-RX28H to the Tilt Servo Horns using twelve Hex Socket Head M2 x 3mm bolts.

12 x

STEP 10 - Setting up the power supply
(It should be fairly obvious to NOT have the power supplies plugged in during the following steps. If you haven't figured that out please send the robot back to us and find a new hobby/career.)
Your Robot Turret comes with two power supplies. The 12 volt power supply is for the logic, the arbotiX board, and the 16 volt variable power supply is for the servo power which attaches to the rX Bridge.
Clip the ends off the two power supplies.

(Why doesn't the arbotiX have power jacks? The arbotiX is traditionally a mobile robot controller powered by batteries and that is why it has terminal blocks.)

Strip and twist the wires as shown leaving about 1.5 cm of bare wire.

For the 12V power supply:
Red = Positive (+)
Black = Negative (-)

For the variable power supply:
Brown = Positive (+)
Blue = Negative (-)
Fold the bare wires in half and twist some more. This makes them thicker and helps provide a much more secure fit in the terminal blocks.

Remove the J1 jumper from the arbotiX

Mount the rX bridge as shown using the Hex Button Head 4-40 x 3/4" bolt and the plastic spacer.

1 x 1 x
Screw the power supply wires into the terminal blocks. Make sure the 12 Volt power supply is on the lower terminal block on the main board and the 16 volt variable power supply is on the rX bridge.



Set the Variable power supply to 16 volts. The switch should be 1 click to the right. The printed voltages and lines are sometimes lined up poorly. Make sure to count the clicks instead of relying on the white lines.

STEP 11 - Mount the servos to the Top Base Plate
Using four Hex Socket Head M2 x 8mm Bolts the Pan Servo back bracket to the Top Base Plate.

4 x
Bottom View of mounted servos to Top Base Plate.

STEP 12 - Mount the top section to the Bottom Base Plate
Use a servo cable to plug the Tilt Servo into the Pan Servo as shown. (You can use which ever jacks you prefer. The order does not matter.)

Plug in the second Servo Cable to the free Pan Servo Jack. Route the Servo Cable through a slot on the upper base. (Again, jack preference is up to customer.)

Screw the M/F 6-32 5/8" standoff into the F/F 6-32 1.25" standoff. Tighten them snugly by rotating about a quarter turn past when the faces touch.

4 x 4 x
Mount the standoffs to the upper base using four 6-32 x 1/2" hex button head bolts.

4 x
Mount the top base to the bottom base as shown using four Hex Button Head 6-32 1/2" bolts. The best orientation is to have the blue terminal power blocks on the back side facing the same way as the back lip of the F8 Frame.

4 x
Plug the servo cable into the rX Bridge.

Plug the FTDI into the arbotiX. Make sure you have the black wire on the right.