A low-cost, education-friendly SCARA robot with 3 planar DOF (base rotation + shoulder + elbow) and a position-controlled pneumatic gripper for Z/height pick-and-place. It’s designed around semi-mainstream components and hybrid fabrication: 2D CNC plates + FDM-printed brackets (nylon/PA or CF-nylon), assembled into robust 3D mechanisms.

How it works 

1. Arm kinematics: Two coaxial revolute joints place the forearm; a third joint (wrist/forearm) aligns the gripper.

2. Parallel actuation layout: Motors are placed near the base with timing belts to keep moving mass low.

3. Z & grip: A compact pneumatic vertical slide or lift plus a position-controlled pneumatic gripper handles varying part heights.

4. Control loop: Encoders → controller (e.g., STM32/ESP32) → motor drivers → actuators; high-level commands come from a PC (Python) doing inverse kinematics.

Build it: step-by-step

0) Bill of Materials (typical)

• Motion: 3× NEMA-17/23 steppers (or compact BLDC servos), GT2/HTD pulleys & belts, sealed radial bearings (608/6001), shoulder/elbow shafts, idlers.

• Structure: 6–8 mm aluminum (or G10/FR4) plates for base/links, 3–4 mm for brackets; FDM-printed spacers, guards, wire guides (nylon/PA-CF).

• Pneumatics: Mini cylinder or slide for Z, position-controlled gripper (with proportional valve or step-valve + pressure sensor), regulator, tubing, fittings.

• Electronics: MCU (STM32/ESP32), stepper drivers (TMC5160/2209 or servo drivers), 24 V PSU, 5 V rail, limit/home switches, incremental encoders, e-stop.

• Misc: Cable chain, ferrules, heat-set inserts, Loctite 243, thread-forming screws for plastics.

1) CAD & drawings

• Lay out 2D plates (base, shoulder, elbow, motor/bearing plates) so they can be CNC-cut from sheet.

• Add datum features (dowel holes/slots) to make alignment foolproof.

• Export: DXF for plates, STL for printed parts.
  Image to include: Exploded view labeling plates, printed brackets, and pulley paths.

2) Fabrication

• CNC plates: 2D mill; deburr edges; ream bearing bores to size.

• 3D prints: Nylon/PA-CF, 0.2–0.28 mm layer, 4+ perimeters, 40–60% infill; orient to maximize fiber along load paths.
  Image to include: Flat-lay of all cut plates + printed parts with part numbers.

3) Mechanical assembly

1. Press bearings into link plates; verify slip-fit shafts.

2. Build base: mount motors, idlers, and first-stage pulleys; route belts but leave slack.

3. Stack shoulder then elbow assemblies; install shafts and spacers; check free motion.

4. Tension belts (finger-tight + ¼ turn) and apply a drop of threadlocker.

5. Mount pneumatic Z slide and gripper; verify full travel.
   Image: Belt routing close-ups; Short video (10–20 s): arm moving freely by hand.

4) Electronics & pneumatics

• Wire MCU → drivers → motors; add home switches (base, shoulder, elbow) and an E-STOP in series with driver enable.

• Plumb regulator → valves → cylinder/gripper; place a pressure sensor for closed-loop grip force.

• Add strain relief + cable chain; keep air lines out of the work envelope.
  Image: Wiring diagram; Video: power-on + E-STOP test.

5) Firmware bring-up

• Set steps-per-rad (or encoder ticks/rad), max accel/velocity, and soft limits.

• Home sequence: base → shoulder → elbow → Z; store offsets.

• Expose a simple UART/USB API: GOTO x y z θ, OPEN, CLOSE, SET_GRIP_FORCE.
  Clip: Serial console showing commands and motion.

6) Kinematics & PC control

• Implement inverse kinematics (IK) for SCARA: given (x, y) solve shoulder/elbow; wrist aligns tool angle.

• Add workspace checks and singularity guards (elbow-up/down).

• Python control script: teach points, linear move (interpolate in task-space), and pick-place sequence.
  Video: Picks from tray A, places to tray B.

7) Calibration & testing

• Link length calibration: move to gauge points, fit actual lengths to minimize IK error.

• Backlash/belt tension: jog direction reversals; tune jerk/accel; retension belts if overshoot.

• Pneumatic tuning: set regulator, valve PWM/step mapping, and grip force vs. pressure curve.
  Image: Calibration fixture or printed jig; Clip: accuracy test placing pins into a pegboard.

8) Safety & enclosure (recommended)

• Interlocked acrylic guard or light curtain; e-stop within reach; current limits set conservatively.

• Label pinch points and add soft end-stops in firmware.