Troubleshooting
Common hiccups with the Robotic Arm Kit and how to fix them — from connection trouble to a joint that won't stay put.
- 1
A joint goes limp or points the wrong way
Don't worry if it looks like your robot “died” — an arm going limp is totally normal (and the most common problem), and it just means a screw is too loose. Even if a screw started out tight, it's normal for it to loosen over time from repeated motion, bumping the table, and so on. To fix it, press the Re-Align button on the control panel (at the top of the page, next to the tutorial button). This moves all the motors to their centered position. If a motor doesn't reach the center, move it there by hand and then re-tighten whichever screw is loose. The most common one is the blue “shoulder” joint, since it supports the most weight. Once your robot's centered position matches how it looked right after building it, screw the screws in TIGHT! A loose screw will cause the joint to fall off again, causing the same problem. Once all the screws are tight, press the “Yep — it's in its center position” button to confirm and watch it move back to its idle position.
- 2
Broken or damaged parts
The delicate parts used to build these robots can be tricky to ship — sometimes a servo, control board, or 3D-printed piece arrives damaged. If that happens, message us on Etsy. We'll give you personalized help and send replacement parts if needed.
- 3
Wiring issues (orientation and slot)
Incorrect wiring is a common problem, and one with a significant impact. Each servo wire has three colored strands — yellow, red, and brown — that must match the labels on the board (yellow toward the black box, brown facing you). Each servo also goes into a specific numbered slot, 1 through 6, in the order the tutorial gives them. A backwards wire, or a wire in the wrong slot, makes that servo do the wrong job and can damage your robot.
- 4
The robot won't connect
First, make sure both batteries are plugged in and the blue light on the circuit board is on. If the RobotArm network doesn't show up, try unplugging the batteries and plugging them back in. If you still don't see it, turn your Wi-Fi off and back on and wait a minute — it can take a while to be discovered. And if you can see the network but tapping it says it can't connect, try a different device; this is usually caused by a setting on your device that's blocking the network.
- 5
The blue light won't turn on
The blue light on the circuit board sometimes doesn't come on the first time you plug in. If it's off, unplug both batteries and plug them back in. A steady blue light means the board has power and is ready to go. If it still doesn't turn on, check where the 9-volt battery connectors connect to the circuit board — it's possible they've come loose. If that's the case, you'll need a flathead screwdriver to re-tighten the terminal that clamps the wire in place.
- 6
The arm shakes or jitters
During the build, the arm keeps correcting itself to stay centered — that shaking is normal, and you can gently hold it still. In everyday use some shaking is expected too: these are small hobby servos, not precision industrial motors. If it shakes out of control, stop it gently with your hand. If it happens often, your batteries may be running low.
- 7
The robot freezes or moves weakly
This usually comes down to power. Make sure both batteries are plugged in — one alone can't supply enough. If the arm can't lift itself, acts erratically, or shuts off, the batteries are likely low; replace both with new 9-volt batteries (we recommend the Amazon Basics ones that came with the kit).
- 8
The gripper struggles or loosens
The gripper is designed for small, lightweight objects. Trying to pick up something too heavy puts extra load on the servos, wears them down faster, and can loosen the screws that hold the arm together. Keep the loads light.
- 9
A servo motor stops working
An easy way to tell if a servo has died is if you feel it and it's pretty hot, or if it starts making a loud screeching noise. We include an extra servo motor in the kit, so if one arrives not working — or wears out after repeated use — you're covered. Just swap the broken servo out for the spare. The exact steps depend on which motor failed: find the tutorial step that showed you how to install that servo, and repeat it to put the new one in. If more than one servo breaks, or you'd like extra servos for your own projects, you can find them cheaply on Amazon — just search for “MG90 servos”, as they're all mostly the same. If you want the exact ones we use, follow this link.
- 10
External modifications
Our policy: we want you to get the original, unmodified kit fully working first. Once you've done that, we can't tell you what to do with it — that curiosity is exactly why you're here! But if you've modified the kit in any way, including changes to the code, we're no longer able to provide support for it. We can only help with the base, unmodified kit.
Still stuck?
If you've got a specific problem that isn't covered here, message us on Etsy — we'll help you sort it out as quickly as we can. Please use this courteously, and only when it's truly necessary.