Sixi 2 robot arm
6. Shoulder Gearbox
Step 1 Tools and Parts Required for this Chapter
Step 2 Clamped Rotors - Parts and Notes
Step 3 Clamped Rotors
- Note:
The process for "T" Rotor and "B" Rotor is the same. We will use T rotor as our guide and repeat the same process for B rotor
Insert 6702 Bearing on one half of the T Rotor
Place the other half and clamp the Bearing together
- Warning:
Make sure to align the T label, The holes and the teeth won't line up if this isn't done correctly.
Insert M3x5mm Screws and Hex Nuts on each half of the Rotor and tighten all the Screws.
- Note:
Repeat the same Process for B Rotor
Step 4 Eccentric Input Shaft - Parts
Step 5 Eccentric Input Shaft - Notes
Step 6 Eccentric Input Shaft - 1
Put the 6702 Bearing on the Thicker Concentric piece of the Shaft Holder
- Note:
Notice that the thinner piece of the Shaft Holder has 2 sides, one where screw lined up to the center of the face and other which is eccentric
Clamp Shaft Holder Cam pieces using M3x30mm Screws
Thicker piece is the Screw Head side,
Only screw in until the tip of the screw is flushed with the face of the thinner piece
Step 7 Eccentric Input Shaft - 2
Step 8 Eccentric Input Shaft - 3
Step 9 Shoulder Gearbox Housing - Parts
Step 10 Shoulder Gearbox Housing - Housing Preparation
Step 11 Shoulder Gearbox Housing - Rotor Alignment
- Warning:
Alignment of the rotor is critical for these gearbox to work.
- Note:
Notice that there are 2 "T" Labels on the T rotor, and same with B rotor with "B" Labels
T is aligned in between 2 teeth of the Top Rotor while B is aligned to the middle of a tooth
Make a Sharpie Mark in between the teeth of T Rotor Where the "T" is Labeled
For B Rotor, Make a sharpie mark on the tooth where the "B" is Labeled.
The Correct Alignment will look something like the Third Picture
Step 12 Shoulder Gearbox Housing - Housing Clamp
Once the Rotor is Properly aligned, all 12 inner holes will have the same space between them when looking directly above it
- Warning:
The Angle of the picture taken of the aligned Rotors are a bit off.
Carefully insert the Rotor while maintaining this position on the Housing with the pins.
- Warning:
Make sure the Motor Shaft Adapter side of the shaft is Pointing out
Press the second half of the housing into place.
- Note:
Verify that you can manually turn the eccentric shaft in the center and that the rotors smoothly turn inside the housing. Tight printing and misaligned rotors can cause the gearbox to jam.
Clamp the other half of the Housing using M3x25mm Screws and Nylock Nuts
Secure tightly using the 5.5mm Socket Driver to hold the Nuts.
Step 13 Shoulder Gearbox Bottom - Parts
Step 14 Shoulder Gearbox Bottom - 1
Align the Bearing Insert of the Gearbox Bottom Sensor Side Piece to the Shaft Holder Cam Bearing of the Input Shaft
Insert M3x45mm Screws all the way through
- Warning:
If Screws aren't going in correctly, you will have to re do the steps, go to aligning the Rotor Step
Keep the Gearbox laying on its side for easier assembly
Step 15 Shoulder Gearbox Bottom - 2
Step 16 Shoulder Gearbox Bottom - 3
Step 17 Shoulder Gearbox Motor
- Note:
Prepare the following components:
Assembled Shoulder Gearbox
NEMA24 100mm Motor
M5x20mm Screws (x4)
Align the D-Cut of the Motor Shaft to the Gearbox Input Shaft and insert the motor all the way through.
Align the motor body so the cable is pointing towards the bottom and secure the position using M5x20mm Screws
Step 18 Shoulder Gearbox Sensor - Parts
Step 19 Shoulder Gearbox Sensor - Preparation
Also prepare 6-pin Ribbon Cable F/O - Brown to Blue {sensor 1 Shoulder} - [365mm]
- Warning:
There is a separate assembly guide for all sensor cable which shows the length of each as well.
Connect the Cable to the AS5147 Sensor as shown in the second picture
Insert the Neodymium Magnet in the Shoulder Magnet Holder
Step 20 Shoulder Gearbox Sensor - 1
Partially screw in two M2x6mm screws in the Sensor Adapter with the screw head insert.
Secure the Sensor Adapter to the Sensor Side of the Gearbox with 2 screw on the bottom side of the 4 holes
Feed the Sensor Cable through the Tunnel
Then use the remaining M2x6mm Screws to Secure the Sensor to the Sensor Adapter
Chip is facing outward


![[3D] - 2GB Shoulder GB Rotors](images/originals/image-1033.jpg)
























![[Opt.] if the nuts are too loose in the insert, use M5x20mm Screws (or any M5 screws) to hold it in place during assembly](images/originals/image-1102.jpg)






![Also prepare 6-pin Ribbon Cable F/O - Brown to Blue {sensor 1 Shoulder} - [365mm]](images/originals/image-1122.jpg)








