Hardware Engineering / Manufacturing

DIY Injection Molding Machine

Designing and building a pneumatic injection molding machine from scratch using a 12-ton H-frame shop press, SC80 pneumatic cylinder, and PID-controlled heating system. Bridges the gap between 3D printing and professional manufacturing at a $425 build cost.

~4 min
Cycle Time
48g
Shot Capacity
1,388
PSI Injection
$425
Build Cost

This project involves designing and building a pneumatic injection molding machine from the ground up, using a 12-ton H-frame shop press as the structural foundation. The machine bridges the gap between hobbyist 3D printing and professional injection molding, enabling small-batch production of plastic parts in HDPE and polypropylene at a fraction of commercial equipment costs.

The system combines an SC80 double-acting pneumatic cylinder for injection force, PID-controlled band heaters for precise temperature management, and interchangeable CNC-machined aluminum mold plates. Six specialized Claude Code agents track machine build progress, inventory, process parameters, quality metrics, and production coordination.

Press
12-ton H-Frame
Structural foundation
Injection
SC80 Pneumatic Cylinder
Double-acting, 140 PSI
Control
REX-C100 PID Controller
Temperature regulation
Heating
380W Band Heaters
200–220°C range
Sensor
K-Type Thermocouple
Temperature feedback
Power
25A Solid State Relay
Heater switching
Design
CNC / Lathe / CAD
Fabrication tools
Tracking
Claude Code Agents
6 specialized agents
01

Pneumatic Injection System

SC80 double-acting cylinder at 140 PSI delivers ~1,090 lbs of injection force. Through a 1-inch barrel, this translates to ~1,388 PSI — sufficient for HDPE and polypropylene processing.

02

PID Temperature Control

REX-C100 controller with 380W band heaters and K-type thermocouple maintains precise temperature at 200–220°C. 25A solid state relay handles power switching.

03

Modular Mold Design

Interchangeable aluminum plates with CNC-machined cavities. Vise-clamped system allows rapid mold swaps between production runs.

04

Multi-Agent Tracking System

6 specialized Claude Code agents — Machine Builder, Inventory Tracker, Process Engineer, Quality Inspector, Product Coordinator, and Session Tracker.

05

Shop Integration

Leverages existing shop infrastructure — CNC mill, lathe, and air compressor — to minimize build cost while maintaining professional-grade capabilities.

06

Quality Control System

Defined specifications for dimensional accuracy, visual standards, and functional testing. Event-driven tracking with semantic hashtags (#milestone, #params, #shot, #defect).

Mechanical, thermal, pneumatic, and software systems that comprise the injection molding machine.

Mechanical
12-ton Press
SC80 Cylinder
Steel Barrel
Mold Plates
Thermal
Band Heaters
PID Controller
Thermocouple
SSR
Pneumatic
Air Compressor
Regulators
Solenoid Valve
Control Circuit
Software
Claude Agents
Inventory DB
Session Logs
Quality Metrics
Completed
  • Machine design
  • Press acquired
  • Cylinder on hand
  • Barrel sourced
  • Heaters received
  • Compressor available
In Progress
  • Barrel machining
  • Mounting bracket design
  • Electrical panel wiring
Upcoming
  • Pneumatic assembly
  • First mold design
  • System integration