A custom controller for bench lathes using a Teco EV Micro Drive VFD with integrated tachometer display.
- Speed Control: 0-10VDC analog speed control via potentiometer
- Motor Control: Run, jog, and emergency stop switches
- Direction Control: Forward/reverse toggle switch with center-off position
- Tachometer: Real-time RPM display with 4-digit 7-segment LED
- Compact Design: 5" wide case with side mounting
- Cost Effective: $98-162 total build cost using VFD internal power supplies
- VFD: Teco EV Micro Drive (handles all motor control)
- Microcontroller: Adafruit FLORA (tachometer display only)
- Display: 4-digit 7-segment LED with MAX7219 driver
- Sensor: TCST2103 slotted optical switch with brass interrupt wheel
- Leverages VFD's internal 24VDC and 10VDC power supplies
- Direct switch connections to VFD digital inputs
- Brass interrupt wheel machined with HSS slitting saw
- 3D printable case with front controls and side mounting
├── assembly/
│ └── assembly-guide.md # Complete build instructions
├── bill-of-materials.md # Component list with costs
├── case/
│ ├── controller-case.scad # OpenSCAD case design
│ └── controller-case.stl # Ready-to-print STL file
├── claude-logs/ # Development logs
├── firmware/
│ └── flora-tachometer.ino # Arduino firmware
├── wiring/
│ ├── flora-tachometer.md # FLORA circuit diagram
│ └── vfd-connections.md # VFD wiring guide
└── ev_operating_manual.pdf # VFD reference manual
- Review Documentation: Start with
bill-of-materials.mdandassembly/assembly-guide.md - Machine Parts: Create brass interrupt wheel using milling machine and HSS slitting saw
- 3D Print Case: Use provided STL file with 0.2mm layers, 20% infill
- Build Electronics: Follow wiring diagrams in
/wiring/directory - Program VFD: Set parameters as specified in VFD connections guide
- Install & Test: Mount controller and calibrate tachometer
- Material: 360 brass, 1/8" thick, 2-3" diameter
- Slots: 60 slots at 6° indexing intervals
- Machining: HSS slitting saw (1/8" × 3" × 30T) at 500-800 RPM
- Power: VFD internal supplies (24VDC for switches, 10VDC for speed control)
- Tachometer: 60 pulses/revolution, 250ms update rate
- Display: Auto-blanking leading zeros, 0-9999 RPM range
- Size: 127mm × 80mm × 180mm (5" × 3.15" × 7")
- Mounting: Side tabs with M5 holes
- Controls: Front-facing layout for easy access
- Emergency Stop: Hardwired NC contacts to VFD fault input
- Electrical Isolation: All control circuits isolated via VFD
- Secure Mounting: Side-mounted case with tamper-resistant design
| Category | Cost Range |
|---|---|
| Electronics | $35-50 |
| Mechanical | $25-40 |
| Case/Hardware | $15-25 |
| Machining Materials | $15-25 |
| Total | $90-150 |
- 3D printer (for case)
- Milling machine with indexing capability
- HSS slitting saw (1/8" thick)
- Soldering equipment
- Basic hand tools
- Arduino IDE with LedControl library
- OpenSCAD (for case modifications)
MIT License - See LICENSE file for details
This is a DIY project. Please review all documentation carefully before beginning construction. Ensure proper electrical safety practices when working with 115VAC power.