ArmXRP Alpha - 100% Screwless 3D Printed Robotic Arm

ArmXRP Alpha is a fully 3D-printed, screwless robotic arm designed around the SparkFun XRP robotics ecosystem. Built with the SnapBolt-HexClip assembly system, ArmXRP can be assembled without screws, fasteners, or tools, making it an accessible platform for students, educators, and robotics builders. The arm features 4 degrees of freedom plus a modular end effector and is capable of lifting payloads up to approximately 150 g.

This upload contains all 3D-printable parts for the mechanical assembly, including the base, joints, arm links, modular end effector components, gear train elements, and an included 3D-printed table clamp. The design incorporates planetary gearboxes, bevel gearsets, spur gears, and worm drives to explore a wide range of mechanical power transmission concepts in a compact educational robotic arm.

ArmXRP Alpha uses the SnapBolt-HexClip system, allowing parts to be assembled, removed, and reconfigured without tools. This makes the platform especially useful for classroom environments, robotics clubs, project teams, and rapid prototyping. The modular end effector attachment system allows different grippers, tools, or experimental attachments to be swapped onto the arm for future expansion.

Designed as part of the broader XRP ecosystem, ArmXRP Alpha is intended to give students a hands-on way to explore robotics, mechanisms, gear reduction, motion control, end effectors, and mechanical design. Once printed and assembled, the arm can be paired with motors, electronics, and XRP-based control systems to create a complete educational robotic manipulation platform.

Assembly Video

OnShape Assembly and Files

Bill of Materials (with and without existing XRP Kit)

Starter Code

Printing Instructions:
All STL files include custom-designed support material, so no slicer-generated supports are needed. Each part is also pre-oriented for printing and should import into your slicer in the correct orientation.

In addition to the individual STL files, which include part quantities in the file names, this release also includes grouped STL files organized into three plate folders. These plate groups are designed around the standard 256 mm × 256 mm Bambu Lab build volume.

If your printer has a similar build plate size, you can open one of the plate folders, select all files with Ctrl+A, and import them into your slicer together. The parts in each plate folder are already duplicated to the correct quantities and saved in the correct print orientations. After importing, use your slicer’s auto-arrange tool, review the layout, and print.

This grouped-plate workflow is intended to save setup time while still allowing users to print individual parts if needed.

STEP files available in attached ZIP.

Alpha Release Notice:
ArmXRP is currently in alpha and represents an early complete release of the system before beta refinement. The platform is functional and demonstrates the core mechanical architecture, screwless assembly system, modular end effector interface, and XRP-based robotic arm concept. However, this release is still intended for testing, feedback, and iteration.

As an alpha release, some parts may require careful printing, tuning, or minor adjustment depending on printer calibration, material choice, and assembly conditions. We welcome feedback from educators, students, makers, and robotics builders. Your experience with printing, assembling, testing, and modifying ArmXRP will help guide the next stage of development toward a more polished beta release.

Please send all feedback to: [email protected], thanks!!