DIY 3D Printed Dremel CNC
π Overview
3D printing is great for rapid prototyping, but it has a ceiling when it comes to strength, surface finish, and material variety. Nikus's approach was straightforward: if you can't afford a commercial CNC, build your own desktop engraver from 3D-printed parts plus standard aluminium extrusion, and use the Dremel rotary tool most makers already own as the spindle.
The machine uses 20x20 aluminium extrusion for the frame, 12mm smooth rods with linear bearings for the guides, and NEMA17 steppers plus lead screws to drive all three axes, controlled by an Arduino running GRBL firmware, with the free Fusion 360 and CNCjs as the only software. The author kept the whole build under $300, and it is one of the most widely shared DIY CNC designs online.
π§° What you need
- 20x20mm aluminium extrusion: 600mm x2, 300mm x5
- 12mm smooth rod: 310mm x2, 530mm x2, 140mm x2
- Lead screw: 500mm x2, 280mm x1, 120mm x1
- 12mm linear bearings x12, 608ZZ bearings x4
- M5 T-nuts x36
- Screws: M6x25 x4, M5x10 x34, M5x16 x10, M3x20 x8, M3x12 x32
- NEMA17 stepper motors + stepper driver boards x4
- Arduino (UNO/Nano) + CNC Shield
- 12V high-current power supply, DC barrel jack, jumper wires
- Dremel rotary tool (spindle) + 3D-printed parts (frame brackets, motor mounts, etc.)
π§ Step by step
Watch the videos first
The author filmed six complete assembly videos - skim through them before you start building
The videos and the written guide complement each other, so jump to the matching video segment whenever a step is unclear
Inventory the parts
Check the extrusion, smooth rod, and lead screw lengths item by item against the Excel list - don't mix them up
Print the 3D parts with a high infill (40%+); for structural parts it is worth printing a spare set
3D print the structural parts
Print the STL files in batches, paying attention to supports and print orientation
Ream every mounting hole with the matching drill bit or tap to keep assembly accurate
Prepare before assembly
Fit the linear bearings onto the smooth rods first and confirm they slide smoothly without binding
Aligning the lead screw with the coupler is critical - any offset causes vibration and wear
Assemble the Z axis
Z travel is short, so watch the limit switch position to avoid crashes
The spindle clamp must hold the Dremel firmly - concentricity directly affects machining accuracy
Assemble the X axis
The X span is long, so the two smooth rods must be parallel - check with calipers
Tension the belt or lead screw moderately: too tight strains the motor, too loose introduces backlash
Y axis and aluminium frame
Lock the extrusion into a rigid frame with T-nuts and hex screws
Tighten lightly at first, then torque everything down once it is square so the frame does not twist
Install the work table
Table flatness affects cut quality - use shims for fine adjustment
Leave T-slots or holes in the bed so workpieces are easy to clamp
Mount the spindle
Hold the Dremel with a printed mount and keep it perfectly vertical
You can add a dust-collection port to cut down on chips
Flash the GRBL firmware
Upload GRBL to the board with the Arduino IDE and set the steps per mm for each axis
Configure steps, acceleration, and limits item by item in the $$ settings - one wrong value and the machine runs wild
Wire the electronics
Plug the stepper drivers into the CNC Shield; mind driver current and cooling
Wire the limit switches as normally closed for safety, and use terminal blocks so faults are easy to trace
Power it up
Feed the motors from a high-current 12V supply and tie logic and power grounds together
Always fit a main switch and a fuse - safety first
Tidy the wiring
Secure cables with trunking and zip ties, and use drag chain on the moving parts
Clean routing prevents snagging and signal noise while the machine moves
Connect CNCjs
Install CNCjs on your computer and connect to the board over serial
Dry-run the G-code first to confirm the axis directions, then fit a cutter and start cutting
Generate toolpaths in Fusion 360
Fusion 360's personal licence is free and its CAM module produces the G-code
Watch the work coordinate origin and tool zeroing; beginners should practise on foam or softwood
Safety
Wear goggles, add an emergency stop, and keep your hands out of the cutting area
The tool spins fast and plastic dust is flammable - keep the area ventilated
See the results
Once tuned, the machine cuts wood, acrylic, and PCB
The author shows plenty of finished parts - very satisfying
Learn your milling basics
Climb vs conventional milling, and matching feed rate to spindle speed, are essential beginner skills
Take lighter depth-of-cut passes instead of one heavy cut
Look at community mods
There are lots of community upgrades, such as dust collection and spindle swaps
Upgrade in small steps to match your own needs
Room to grow
You can add a laser head, a fourth axis, or a stiffer spindle
The aluminium-frame design scales very well
Wrap-up
The whole project is a complete mechanical, electronic, and software loop
Follow the steps - most parts are off-the-shelf and it is well worth trying
π‘ Tips
- The aluminium extrusion and motors are the main cost; local hardware stores often make the real build cheaper than the author's $300
- Beginners should assemble the mechanics and dry-run first, then wire and tune - troubleshooting is much easier that way
- GRBL's $100/$101/$102 steps-per-mm values come from (steps per revolution x microstepping) / lead; always verify the actual travel distance