Converting a manual lathe to CNC

So you have a manual lathe and want to make it a CNC. Here's everything you need — no more, no less.

The checklist

1. FluidBoard

The controller itself. Handles motion control, spindle communication, threading, tool offsets, and everything else — standalone, no PC required.

2. External stepper drivers and motors

Your stepper motors need to keep up with the spindle during threading. When the controller synchronizes axis movement to spindle rotation, the steppers need enough torque and speed to follow. For most lathes, that means NEMA-24 or larger stepper motors.

We recommend closed-loop stepper drivers (like the CL57T or similar). They're not much more expensive than open-loop drivers, and they give you:

• Stall detection — the driver knows if the motor loses steps and can raise an alarm
• Higher performance — closed-loop drivers can push the motor harder because they know its actual position
• Open-loop fallback — most closed-loop drivers also work in open-loop mode, so you're not locked in

Contact your stepper driver vendor for details on your specific setup. The FluidBoard works with any driver that accepts 5V step/direction/enable signals — which is virtually all of them.

See the external drivers page for wiring and pinout details.

3. Your existing spindle

Keep whatever spindle and motor are already on your lathe. The FluidBoard controls spindle speed through your VFD (via RS485 or 0-10V), but the physical spindle stays as-is.

If your lathe doesn't have a VFD yet, you'll need one for speed control. Match the VFD to your spindle motor's specifications.

4. Spindle encoder

A ~500 PPR quadrature encoder, mounted on the spindle shaft or connected via a belt/gear. This is what enables threading, feed-per-revolution, and speed monitoring.

This is the part that most people haven't heard of. Without it, you have a CNC router bolted to a lathe — with it, you have an actual CNC lathe.

See the spindle encoder page for what to buy and how to wire it.

5. Endstops

One per axis, at the home position. These establish the machine coordinate system at startup. Wire them to the FluidBoard's opto-isolated inputs.

See the endstops page for wiring and configuration.

6. Emergency stop

A physical e-stop button, wired to the FluidBoard's dedicated stop input. The controller performs a controlled stop — braking the spindle through the VFD and halting all axes — which is faster and safer than just cutting power.

Combined with state persistence, hitting the e-stop doesn't lose your position. You power back on and continue.

See the e-stop page for wiring options.

7. Power supply

A 36V or 48V DC power supply for the stepper drivers. The FluidBoard itself runs from 12–48V DC, and generates its own 12V, 5V, and 3.3V rails internally.

8. Wiring

• CAT-6 shielded cable for RS485 to the VFD — see RS485 wiring
• Shielded cable for encoder signals
• Standard wire for step/dir/enable to stepper drivers
• Keep signal cables away from VFD output and mains wiring

What you don't need

• No PC — the FluidBoard runs standalone. Configure it once over WiFi or Ethernet, then send G-code from the web interface, an SD card, or any GRBL sender.
• No parallel port — this isn't a breakout board. The FluidBoard is the complete controller.
• No license — the firmware is included. You get free updates, indefinitely.
• No external motion controller — the ESP32-S3 handles motion planning, acceleration, and step generation internally.

What you get for €125

A complete lathe controller with threading (G33/G76), constant surface speed (G96), feed per revolution (G95), tool table, cutter radius compensation, S-curve acceleration, WiFi, Ethernet, RS485, 0-10V output, opto-isolated inputs, state persistence, USB camera support, and LED strip feedback.

Typical setup order

1. Mount the stepper motors and drivers, wire to the FluidBoard
2. Mount the endstops, wire to inputs
3. Mount the spindle encoder, wire to encoder inputs
4. Wire the VFD (RS485 or 0-10V)
5. Wire the e-stop
6. Connect power
7. Upload a config file and home the machine
8. Set up your tool table
9. Run your first threading test