In the industrial robotics cobots space, the first fork in the road is whether you need a moving arm or a sensing device. The ARM-21N4 5-DOF Robot Arm Kit and the ATI Industrial Automation Mini45 are both sold for robotics work, but they do very different jobs. The ARM-21N4 is a low-cost, unassembled mechanical arm kit with servos; the ATI Mini45 is a force/torque sensor designed to let a robot feel the forces it applies. This head-to-head breaks down what each actually gives you, so you can pick the one that matches your next build.
Quick verdict
If you're starting a robotic arm project from scratch and need the mechanical structure plus servo-driven joints, the ARM-21N4 is the affordable foundation. If your arm is already assembled and you need to add force/torque feedback for contact detection or load monitoring, the ATI Mini45 is the sensing component to spec in. They're not direct substitutes; they serve different roles in the same ecosystem.
At a glance
| ARM-21N4 5-DOF Robot Arm Kit | ATI Industrial Automation Mini45 | |
|---|---|---|
| Listed price | USD 119.23 | USD 1,395.00 |
| Condition | New | Used \& Functional |
| What it is | 5-DOF mechanical arm kit with 20KG digital servos | Force/torque sensor for robot arms |
| Key attributes | Metal gears + double bearings output; gripper holder for suction cups, electromagnets, forks, craws, grippers | Measures forces/torques in X, Y, Z axes; Controller Platform: Automate |
| Best for | Prototyping an arm structure with servo motion | Adding force feedback to an existing arm |
Where each product wins
The ARM-21N4 wins on price and on being a complete mechanical starting point. You get a multi-joint arm with the drive components included, and the gripper holder works with common end effectors. The ATI Mini45 wins on sensing. It tells you what forces and torques a robotic arm is experiencing, which is critical for contact feedback in tasks like assembly or polishing. Use the ARM-21N4 when you need the arm itself; use the ATI Mini45 when you need the arm to feel.
ARM-21N4 5-DOF Robot Arm Kit
This kit gives you a 5-degree-of-freedom arm structure with 20KG digital servos, metal gear output, and double bearings at the movable joints. The gripper holder is designed to attach suction cups, electromagnets, forks, craws, and grippers, so you can adapt it to a range of end effectors. The listed price keeps the entry point low for a real robotic arm project. The trade-off is that the arm arrives unassembled, which means you'll spend time putting the joints together and wiring the servos. It is a build-it-yourself kit rather than a ready-to-run arm. The gripper holder lets you choose the end effector that matches your application. If you want to learn the mechanics and build a multi-joint arm, this is a strong starting point.
ATI Industrial Automation Mini45
The Mini45 is a force/torque sensor built to measure forces and torques at the same time in the X, Y, and Z axes. That lets a robotic arm detect contact, load, and tool interaction with high accuracy. This unit is listed as used and functional, removed from working automation and research equipment, with only minor cosmetic wear. It comes with an integrated cable. The price reflects specialized sensing rather than a full arm. The limitation is that it is only a sensor; you still need a robot arm and a control system to use the data it produces. If your arm can't feel what it's touching, this is the piece that adds that capability.
Final choice by use case
Choose the ARM-21N4 if you're building a robotic arm from components and want an affordable 5-DOF structure with servo motion. Choose the ATI Mini45 if you already have a functioning arm and need precise force/torque feedback for safe, adaptive operation. For a complete cobot setup, you could eventually pair both: the ARM-21N4 as the arm and the Mini45 as the sense of touch.
