Custom 3-Axis CNC Router

The main frame is built from aluminum profiles and basic M5 hardware:

• Profiles: 2 × 20×40 mm at 600 mm, 2 × 20×40 mm at 666 mm, 2 × 20×80 mm at 600 mm
• Connectors: simple corner connectors to tie the frame together
• Main fasteners: about 24 × M5×20 mm, 6 × M5×16 mm, 28 × M5×12 mm screws
• Nuts and T-nuts: around 20 × M5 T-nuts and 24 × M5 nuts for mounting plates and rails

The goal here wasn’t to create a perfect, overbuilt frame, just something square and stiff enough that it doesn’t twist easily during cuts. Most of the effort went into measuring, squaring, and tightening things in a sensible order so the frame stays flat.

The motion system combines linear rails, ball screws, and a few belts and bearings:

• Linear rails: 6 × MGN12 rails (2 × 600 mm, 2 × 650 mm, 2 × 200 mm)
• Rail blocks: 12 × MGN12H blocks spread across X, Y, and Z
• Drive screws: 1 × 220 mm trapezoidal lead screw (Z axis), 1 × SFU1605 ball screw at 650 mm, 2 × SFU1605 ball screws at 600 mm
• Bearings: 3 × 6000RS, 6 × 6201RS, 1 × 608RS to support the screws and shafts
• Couplers: 3 × 8–10 mm couplers between motors and screws
• Belt drive: 1 × 200 mm closed GT2 belt with 2 × GT2 pulleys where a belt makes more sense than a direct coupling

Once everything is aligned and tightened, the gantry moves smoothly and doesn't feel loose, which is all I was aiming for.

The cutting end of the machine is handled by a small CNC spindle and a simple mount on the Z axis:

• Spindle: 1 × CNC spindle in the 500 W range (typical ER11-style unit)
• Accessories: basic collet set and wrenches for tool changes

Mechanically, the important part is that the mount is tight and doesn't flex, and that the spindle sits low enough to reach the work area without the Z axis bottoming out. The electrical side of the spindle (power supply or inverter and control) is covered in the electronics section.

Most of the smaller pieces are held together with a mix of standard metric screws and nuts:

• M3 screws: about 14 × M3×16 mm, 60 × M3×10 mm, 26 × M3×8 mm
• M3 hardware: a few standard M3 nuts and around 22 × M3 T-nuts for attaching parts to the profiles
• M5 hardware: the M5 screws, nuts, and T-nuts used for frame joints, rail mounts, and heavier brackets
• M6 screws: roughly 20 × M6×12 mm for spots that need a bit more strength
• Locking parts: 3 × trapezoidal lead screw lock collars and 3 × M12×1 fine-thread nuts to keep the screws in place

It’s basically a small pile of M3, M5, and M6 hardware. Having enough of each size and keeping them sorted made the mechanical build a lot less annoying.

The next step on the hardware side is better chip and dust management. Right now the machine runs open, which is fine for quick tests but not ideal for longer jobs. I plan to add a proper dust shoe around the spindle and a small vacuum system with a cyclone separator and bin under the table, so most of the chips stay out of the shop vac filter. The vacuum would be switched from the control box, either through another relay channel or a dedicated contactor.

If I start cutting more steel or harder materials, a basic mist or oil-cooling setup is also on the list. The idea is a small coolant reservoir with a solenoid valve and a flexible nozzle, controlled from the same auxiliary rail as the fans and lights. That would keep tool temperatures under control on heavier cuts without turning the whole machine into a full flood-cooling project.

The motion system runs from a 36 V SMPS that feeds four DM542-class stepper drivers, one for each NEMA 23 motor (X, Z, and the two Y motors). A second supply provides a 24 V rail for relay coils, fans, and lighting. From there, compact buck converters generate 12 V and 5 V rails for the Arduino, display, and other low-power electronics. High-current motor wiring is bundled separately from the low-voltage harness, and everything ties back to a single star ground point in the main distribution box.

The spindle uses a separate 500 W DC speed-controller PSU (AC 110–220 V in, 0–100 V DC out, 0–10 V control input). Keeping the spindle on its own supply prevents its load spikes from disturbing the 36 V motion rail and makes it easy to service the spindle chain independently.

Axis motion is handled by a dedicated CNC controller board (MKS DLC32 v2.1), which generates step, direction, and enable signals for the external drivers. Each axis uses the same wiring pattern: STEP, DIR, and ENA lines from the DLC32 go into the PUL, DIR, and ENA inputs on a DM542 driver, and the driver outputs feed a NEMA 23 stepper wired in bipolar configuration.

Signal lines between the controller and drivers use short, twisted pairs with a shared reference ground, while the motor outputs run in their own heavier-gauge cables. The emergency stop sits upstream of the 36 V supply, so dropping the E-stop immediately removes power from all drivers while leaving the low-voltage control electronics powered if needed for diagnostics.

Auxiliaries such as cooling fans and work-area lighting are handled in a separate control layer. An Arduino Nano (ATmega328P) sits in the control box and drives a 4-channel relay module based on standard Songle relays. Four front-panel push buttons connect directly to the Nano using internal pull-ups; the firmware debounces them and latches the relay outputs so all auxiliaries power up in a known OFF state.

The spindle speed knob is a panel-mounted potentiometer tied to the spindle PSU's 0–10 V reference output. The Nano only measures this signal: it taps the knob via a simple 1:1 resistor divider and a small RC filter into A0, then maps the voltage to an estimated RPM. That value, along with basic auxiliary status, is shown on a 1.8" ST7735 SPI TFT, which is wired to the Nano over a standard SCK/MOSI/CS/DC/RST interface.

The spindle control path is left open for upgrades. One option is to add a PWM-to-0–10 V converter driven from a Nano PWM output, allowing the firmware to command spindle speed directly. Another is to use an I²C DAC such as the MCP4725 followed by an op-amp stage to generate a stable 0–10 V control voltage. In both cases the spindle PSU should only see one active source on its 0–10 V input at a time—either the front-panel potentiometer or the generated control signal—selected with a hardware switch or an analog switch stage.