SO100 Robot Arm Assembly Guide — Step-by-Step 2026

If you are searching for SO100 robot arm assembly, a practical SO100 robot arm setup guide, or the fastest answer to how to assemble SO100, this is the walkthrough to follow in 2026.

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Most buyers do not want a vague marketing promise. They want to know what actually happens after the box arrives: what parts are included, whether tools are required, how much assembly is left, how calibration works, and how quickly they can reach a real first test.

That is exactly what this guide covers.

One important note up front: the SO100 Complete Kit is designed to remove the painful part of robot-arm assembly. The leader arm and follower arm arrive already built, with the servo stack installed and tested. So for most customers, "assembly" means final physical setup, wiring, calibration, and software bring-up, not printing parts for a weekend and hunting for missing screws.

If you are comparing pre-assembled and DIY routes, read our SO100 pre-assembled vs DIY guide. If you want the broader software walkthrough after hardware setup, go next to the complete LeRobot + SO100 setup tutorial.

1. What’s in the box

Here is the practical SO100 robot arm instructions version of the parts list. When you open a standard SO100 Complete Kit, you should expect the following:

Item	Qty	What it does
Leader arm assembly	1	The arm you move by hand to demonstrate a task
Follower arm assembly	1	The arm that mirrors motion and later runs learned policies
STS3215 serial bus servos	12 total	6 servos per arm, already installed in the complete kit
3D-printed frame parts	Installed	Base, links, wrist structure, and gripper/frame hardware already mounted
Controller / servo driver boards	2	One control path per arm for communication and bus-servo control
USB-C data cables	2	One cable per arm to connect the hardware to your computer
Power supply	1	External power for the follower arm during normal operation
Quick-start material	1	Core setup reference to get you to first movement fast

To make this more concrete, here is what the two arm assemblies represent:

• The leader arm includes the base, shoulder, elbow, wrist, gripper, and six installed servos that let you physically demonstrate a trajectory.
• The follower arm includes the same core mechanical chain and servo layout, but this is the arm you actually validate, record with, and deploy models onto.
• The frame is already mounted in the complete kit, which is why the physical setup is so much faster than a full DIY build.

If you ordered a DIY-style parts bundle or printed your own frame, the checklist above is still useful. The difference is that you will spend additional time physically mounting the servos and frame pieces before the setup steps below. If that is the route you want, our how to build a robot arm guide is the better starting point.

2. Tools required

The good news: the answer to "what tools do I need before starting?" is usually "almost none."

For a standard complete-kit setup, prepare:

• A stable desk or workbench with enough room for two small arms and your laptop
• A laptop or desktop computer with Python installed
• One free power outlet
• The included USB-C cables and power supply
• Optional: a small hex key or precision screwdriver in case you want to snug a screw that loosened during shipping
• Optional: cable labels or tape if you want to clearly mark leader vs follower during setup

You do not need:

• soldering equipment,
• a 3D printer,
• servo crimping tools,
• firmware flashing hardware,
• advanced machining tools.

That matters because most assembly frustration with budget robot arms comes from missing tools, poor print quality, or mechanical rework. The SO100 Complete Kit is intentionally built to skip that.

If your goal is "get moving today," this is also why many buyers choose the ready-to-run SO100 kit instead of a parts-only workflow.

3. Step-by-step assembly

Below is the exact SO100 robot arm getting started flow we recommend. For the complete kit, think of this as final assembly and safe setup.

Step 1: Unbox and separate leader vs follower

Remove everything from the packaging and place the parts on a clean table. Keep the two arms separate from the start. If one arm is labeled, preserve that label. If not, add your own tape label now.

This sounds trivial, but it prevents a lot of confusion later when you are assigning ports, calibrating, and testing teleoperation.

Step 2: Inspect the frame before powering anything

Before you connect cables, do a 60-second inspection:

• Confirm that each base sits flat on the table.
• Check that no servo horn looks obviously shifted from shipping.
• Make sure the gripper fingers are aligned and not jammed against packing material.
• Check that visible cables are not pinched between frame parts.

Do not force any joint through its full range when the arm is powered off. A light manual check for obvious binding is enough.

Step 3: Place both arms in a safe workspace

Put the leader arm and follower arm on a stable surface with some spacing between them. A simple rule is 40-60 cm apart with clear room around the follower arm.

You want:

• enough room to move the leader naturally by hand,
• no object directly in the follower arm’s swing path,
• no cable tension pulling on either base.

If you are setting up for the first time, keep the table uncluttered. Your first test should be about verifying motion, not dodging cups, tools, and loose boxes.

Step 4: Check cable seating and controller connections

On the complete kit, the arm-side servo chain is already wired. What you need to verify is that everything is fully seated after shipping:

• each arm is connected cleanly to its controller path,
• USB-C ports are unobstructed,
• power connections feel firm,
• nothing is hanging loose from the bus-servo side.

If something looks partially backed out, reseat it gently. Do not force connectors at an angle.

Step 5: Connect the leader arm to your computer

Use one included USB-C cable to connect the leader arm/controller to your computer. This is the arm you will move by hand during teleoperation and data collection.

If your operating system prompts for a new serial device, that is normal.

Step 6: Connect the follower arm to your computer and power

Use the second USB-C cable for the follower arm. Then connect the follower arm’s external power supply.

This is the key distinction:

• the leader arm is the demonstration device,
• the follower arm is the powered execution device.

After power is applied, you should be able to confirm that the electronics are alive. If you do not see any sign of power on the controller board, stop here and re-check the outlet, cable, and supply connection.

Step 7: Verify that your computer can see both arms

Before calibration, confirm that both serial devices appear.

# Linux
ls /dev/ttyUSB*

# macOS
ls /dev/tty.usb*

You should see two devices. If you only see one, do not continue yet. Swap the cable, re-seat the connector, or review the fixes in our SO100 troubleshooting guide.

Step 8: Keep the arms unloaded for first bring-up

Do not attach tools, pens, or heavy objects for the first session. Start with the stock gripper and empty workspace.

This reduces the chance of:

• servo jitter under unnecessary load,
• confusing calibration offsets,
• accidental collisions during the first teleoperation test.

At this point, the physical setup is complete. For most buyers, this is the whole real-world answer to how to assemble SO100: unbox, inspect, connect, power, verify, then move into calibration.

4. Calibration

Calibration is the one step you should not rush. It tells the software where each joint sits and how to map motion cleanly between the leader and follower arms.

If you already know you want the deeper software path, keep our full LeRobot setup tutorial open in another tab. This section is the short version.

Basic calibration flow

1. Put both arms in a relaxed, obstacle-free position.
2. Confirm the follower arm has stable power.
3. Note the serial ports for the leader and follower.
4. Run the SO100 calibration command.
5. Follow the prompts slowly and deliberately.

A typical LeRobot-style calibration command looks like this:

python -m lerobot.calibrate \
  --robot.type=so100 \
  --robot.port_leader=/dev/ttyUSB0 \
  --robot.port_follower=/dev/ttyUSB1

During calibration:

• move each joint only through its safe range,
• keep the arm stable when the tool asks you to hold position,
• avoid bumping the table,
• do not attach a payload yet.

Calibration tips that save time

• Start from stock hardware. First calibration is easiest with no add-ons or custom end effectors.
• Use consistent ports. If possible, keep the same leader and follower port mapping each time you reconnect.
• Re-run calibration if motion feels mirrored incorrectly or offset. Do not try to "work around" a bad calibration.
• Do not continue into recording or policy testing until teleoperation looks smooth.

If calibration fails outright, the usual causes are simple: one arm is not fully detected, power is unstable, or a connector came loose during setup. The full diagnostic list is in the troubleshooting guide.

5. First test

Your first test should answer one question only:

Does the follower arm track the leader arm smoothly and predictably?

Run a basic teleoperation command:

python -m lerobot.teleoperate \
  --robot.type=so100

Now move the leader arm gently by hand through small motions first:

• rotate the base slightly,
• move the shoulder a small amount,
• test wrist motion,
• open and close the gripper.

What "working correctly" looks like

• The follower mirrors the leader without long pauses.
• Motion is smooth rather than twitchy.
• The gripper responds consistently.
• No joint slams into a hard stop.
• No cable gets pulled tight during normal motion.

Stop immediately if you see this

• loud grinding,
• violent oscillation,
• a joint moving backward relative to expectation,
• power cutting in and out,
• one axis refusing to respond.

If that happens, stop the test and go straight to the SO100 troubleshooting guide. Most first-test problems come from one of three things: bad cable seating, wrong port assignment, or incomplete calibration.

If the test passes, you are done with the hardware side. The system is ready for recording, replay, and training.

6. Connect to LeRobot

The SO100 is most valuable when it moves from "robot arm that powers on" to "robot arm that can be used for teleoperation and imitation learning." That is where LeRobot comes in.

If you have not installed it yet, the shortest clean setup is:

conda create -n lerobot python=3.10 -y
conda activate lerobot
pip install lerobot
python -m lerobot --help

Once the install is complete, your quick-start path is:

1. Calibrate both arms.
2. Run teleoperation to verify mirroring.
3. Record a small demonstration dataset.
4. Train a first simple policy.
5. Replay or evaluate that policy on the follower arm.

For example, after calibration and a successful first test, a basic recording command might look like this:

python -m lerobot.record \
  --robot.type=so100 \
  --num_episodes=10 \
  --repo_id=your-name/so100-first-task

That gets you from SO100 robot arm assembly to a real software workflow fast. If your goal is imitation learning, continue with:

• the full LeRobot + SO100 tutorial,
• our imitation learning guide for robot arms,
• or the dedicated LeRobot hardware page.

7. Troubleshooting

Here are the most common issues people hit during SO100 setup and the fastest fix for each one.

Problem: Only one arm shows up in the terminal

What it usually means: a cable or port issue.

Fix:

• swap in the other USB-C cable,
• connect directly to the computer instead of a hub,
• re-check that the follower arm power supply is seated,
• re-run the serial port check.

Problem: Calibration starts but the arm behaves strangely

What it usually means: the calibration was interrupted, the arms were bumped, or one joint started from a bad position.

Fix:

• power cycle safely,
• place both arms back in a neutral pose,
• run calibration again from the beginning,
• move each joint slowly and completely when prompted.

Problem: The follower arm jitters or buzzes

What it usually means: unstable power, excessive load, or a cable snag creating resistance.

Fix:

• remove any payload,
• make sure you are using the included power supply,
• inspect cable routing near the moving joints,
• retry the first test with small motions only.

Problem: Motion is reversed or offset on one axis

What it usually means: bad calibration or a configuration mismatch.

Fix:

• do not keep testing,
• rerun calibration,
• confirm leader and follower ports are not swapped.

Problem: Teleoperation works, but it feels rough

What it usually means: calibration is technically complete but not clean.

Fix:

• recalibrate before recording data,
• slow down your hand motions,
• verify the table is stable and the bases are not shifting.

For the long-form version with more fixes, go straight to our SO100 troubleshooting guide.

8. Where to buy

If you want the shortest path from box to working hardware, buy the setup that already matches this guide.

Buy the SO100 Complete Kit now →

Why this is the recommended route:

• you skip 3D printing and parts sourcing,
• you avoid servo-mount alignment work,
• you get straight to calibration and first motion,
• you can move into LeRobot the same day.

If you are still comparing vendors, read our where to buy SO100 guide. If you already know you want the fastest route, the SO100 Complete Kit product guide is the right next click.

FAQ

Does the SO100 robot arm come pre-assembled?

Yes, the SO100 Complete Kit arrives with the leader and follower arms already built. For most buyers, the remaining work is final setup, cable connection, calibration, and a first motion test.

How long does SO100 assembly take?

For the complete kit, most people can finish unboxing and hardware setup in minutes. The full path from sealed box to calibrated first motion is usually much faster than a DIY build. For the exact breakdown, read our SO100 setup time guide.

Do I need special tools to assemble SO100?

No special tools are required for the complete kit. A stable desk, a computer, the included cables, and the power supply are enough. A small hex key or screwdriver is optional if you want to tighten something that shifted during shipping.

What should I do right after assembly?

Calibrate first, then run teleoperation. Do not jump directly into recording demonstrations or training until the follower arm mirrors the leader cleanly.

What software should I install after setup?

Install LeRobot if you want teleoperation, recording, imitation learning, and deployment. Our LeRobot setup tutorial gives the full workflow from install through first policy training.

Final takeaway

The practical answer to SO100 robot arm assembly is much simpler than most buyers expect.

You are not signing up for a long mechanical build. You are setting up a leader-follower robot system that is already optimized to get you to calibration, testing, and software quickly.

If your goal is to start learning robotics, imitation learning, or LeRobot without losing a weekend to assembly, this is the right workflow:

1. inventory the kit,
2. place both arms safely,
3. connect USB and power,
4. calibrate,
5. run the first teleoperation test,
6. move into LeRobot.

That is the shortest path from "my SO100 box just arrived" to "my robot arm is moving correctly on my desk."

Get the SO100 Complete Kit here →