PrintNC Mini: The Small Steel-Frame CNC, What It Is and What to Buy
The PrintNC Mini is a smaller, community-designed version of the PrintNC steel CNC router. It is not a shrunken V4: it has its own CAD model, NEMA17 motors on belts, HGR15 rails and 12 mm ballscrews. Here is what it is, how far along it is, and what to buy.
Table of Contents
What the PrintNC Mini is
The Mini is published by Martin Baadsgaard as a Fusion 360 model and BOM workbook on GitHub (revision 47, December 2023), open source under CC BY 4.0. Like the full-size PrintNC it is a steel-tube router with 3D printed parts, drilled, tapped and bolted together.
Its README is honest about the status: the Mini is a work in progress, it does not have the same support and information as the full-size PrintNC, and the goal is still a reliable, thoroughly tested CAD model. Help comes from the PrintNC Discord, where Mini builders post alongside the full-size community.
PrintNC Mini specs (V47)
These come from the public workbook's 500 x 500 mm frame example. Lengths scale with the frame you choose.
| Part | Mini V47 |
|---|---|
| Travel | About 270 x 301 x 98 mm (X x Y x Z) |
| Frame | 50 x 50 mm square main tubes and 25 x 50 mm cross members on a 500 x 500 mm frame |
| Rails | HGR15 with HGH15CA blocks: six rails and 9 or 11 blocks, depending on the Z variant |
| Ballscrews | Four SFU1204 (12 mm, 4 mm lead): one X, two Y, one Z, with BK10 fixed supports |
| Motors | Four NEMA17 (StepperOnline 17HS24-2104S: 60 mm body, 5 mm shaft, 2.1 A), tucked away and belt-coupled to the screws |
| Drivers | Four DM542-class drivers, or integrated closed-loop NEMA17 motors |
| Controller | GRBLHAL2000 or Flexi-HAL (grblHAL), or LinuxCNC with a parallel-port breakout or Mesa card |
| Spindle | 0.8 or 1.5 kW water-cooled 65 mm spindle with VFD, or a Makita RT0701C router |
Mini vs full-size PrintNC V4
| PrintNC Mini (V47) | PrintNC V4 Metalcutter | |
|---|---|---|
| Cutting area | About 270 x 300 mm | 600 x 600 to 1000 x 1000 mm (preset about 625 x 625) |
| Steel | 50 x 50 mm tube | 75 x 50 x 3 mm base, 75 x 75 x 4 mm gantry |
| Rails | HGR15 / HGH15CA | HGR20 / HGW20CC |
| Ballscrews | SFU1204 on every axis | SFU1610 on X and Y, SFU1204 on Z |
| Motors | 4 x NEMA17, belt drive | 4 x NEMA23, direct couplers |
| Documentation | CAD and workbook, marked work in progress | Project wiki, BOM generator, large build community |
Pick the Mini if your parts are small and your space is tight, and you are happy to work from a CAD model with some open questions. Pick the full-size V4 if you want the documented build with more builders behind it, or a bigger cutting area. Parts are not interchangeable: full-size BK12/BF12, 1610 screws and NEMA23 motors do not fit the Mini.
What the public files leave open
The workbook mixes data from revisions 32 and 47, and a few items disagree. Check these in the CAD model or ask on the Discord before ordering:
- Z ballscrew length: 220 mm in the V47 build calculation, 230 mm elsewhere in the workbook.
- Floating supports: BF10 in one column, KP08 pillow blocks in another.
- Pulleys and belts: GT2, but tooth counts, widths, bores and belt lengths are not filled in.
- Tensioner bearings: listed as 105RS without dimensions.
- Motor torque: the workbook says 0.72 Nm and links an older 0.65 Nm listing; StepperOnline now rates the 17HS24-2104S at 0.76 Nm. Same motor, newer datasheet.
- Printed parts: some rows were copied from the full-size build (BK12/BF12, 2010). Use the Mini parts.
Power supply and spindle
The Mini has no single specified power supply. Match the motor supply to the drivers you choose (24 or 36 V are both used) and give the controller its own supply: the GRBLHAL2000 accepts 12 to 28 V, so never feed it from a 36 V motor rail. The power supply page on the PrintNC wiki explains the sizing.
For the spindle, choose the input voltage for your mains and the output for the spindle's nameplate; a VFD label that says 110 V input does not tell you the output. A 65 mm trim router like the Makita RT0701C skips the VFD and the water loop. Our air vs water-cooled spindle guide covers the choice.
Should you build one?
Build a Mini if you want a small steel machine for aluminium brackets, fixtures and small parts, you are comfortable drilling and tapping steel and wiring electronics, and you do not mind resolving a few open details yourself.
If you want something that works out of the box, compare our best desktop CNC routers and best CNC routers for aluminum.
PrintNC Mini questions
Is the PrintNC Mini finished?
Not fully. The CAD model and workbook are public, but the author marks the Mini as a work in progress with less support and information than the full-size PrintNC.
What motors does the PrintNC Mini use?
Four NEMA17 steppers (the workbook names the StepperOnline 17HS24-2104S), driven by DM542-class drivers and coupled to the ballscrews with GT2 belts. Not NEMA23.
What rails and ballscrews does the PrintNC Mini use?
HGR15 rails with HGH15CA blocks and four SFU1204 ballscrews with BK10 fixed supports. Not MGN12 rails or 1605 screws.
How big is the PrintNC Mini?
The V47 example uses a 500 x 500 mm frame and gives about 270 x 301 x 98 mm of travel.
PrintNC Mini parts list
What you buy for the PrintNC Mini, based on the community CAD and workbook (V47, a 500 x 500 mm frame with a four-block Z). The Mini is still marked work in progress by its author, and a few items below are left open on purpose because the public files disagree with themselves; check the CAD model before ordering those.
Decide these first
- Frame size: the numbers below are for a 500 x 500 mm frame (about 270 x 300 x 98 mm of travel). Rail and screw lengths scale with it.
- Z: two 220 mm rails with four blocks (used here) or two 190 mm rails with two blocks.
- Cutting motor: 0.8 or 1.5 kW water-cooled 65 mm spindle with VFD, or a Makita RT0701C router.
- Motors: four NEMA17 (not NEMA23) on the Mini, with DM542T-class drivers or integrated closed-loop motors.
| Part | What to buy | Qty | Where to look |
|---|---|---|---|
| Frame | |||
| Steel tube The 500 x 500 is the frame, not the cutting area. Use the Mini steel, not the full-size V4 schedule. | 50 x 50 x 3 mm for gantry and Y supports, 25 x 50 mm cross members | 1 x 535 gantry, 3 x 500 cross, 2 x 500 Y | Buy to the spec (local supplier or CAD) |
| Y roller tubes The workbook says both 120 mm and 3.5 inches (89 mm); take the length from the CAD model. | 50 x 50 mm tube, length from CAD | 2 | Buy to the spec (local supplier or CAD) |
| Z plates and lower angle A plywood faceplate is a documented way to start. | Aluminium faceplate 220 x 115 x 12, tramming plate 140 x 130 x 10, angle 25 x 50 x 8, 250 long | 1 each | Buy to the spec (local supplier or CAD) |
| Printed parts | |||
| Motor mounts and guides Do not use the full-size V4 printed parts. | Mini-specific parts from the Mini CAD (3 X/Y motor mounts, 1 Z mount), PETG for motor mounts | 1 set | |
| Motion | |||
| X upper rail HGR15, not MGN12. | HGR15, 450 mm, with 2 HGH15CA blocks | 1 + 2 blocks | |
| X lower rail Different length from the upper rail. | HGR15, 390 mm, with 1 HGH15CA block | 1 + 1 block | |
| Y rails Lengths scale with the frame. | HGR15, 430 mm each, with 2 HGH15CA blocks per rail | 2 + 4 blocks | |
| Z rails Or 190 mm rails with 2 blocks. | HGR15, 220 mm each, with 4 HGH15CA blocks | 2 + 4 blocks | |
| X and Y ballscrews Confirm the end machining against your support and pulley before ordering. | SFU1204, X 540 mm and Y 2 x 510 mm, ends machined | 3 + 3 nuts | |
| Z ballscrew The workbook gives both 220 mm (V47) and 230 mm; check the CAD. | SFU1204 with nut, 220 or 230 mm | 1 + 1 nut | |
| Screw supports and nut housing Never use full-size BK12/BF12 parts on the Mini. | 4 x BK10 fixed, 3 floating supports (BF10 or KP08 per CAD), 1 x DSG12 housing | 4 + 3 + 1 | |
| Pulleys and belts Tooth counts, widths and belt lengths are not in the public workbook; take them from the CAD. No buy link until they are known. | GT2 pulleys and belts for the tucked-motor drive | 4 axis drives | Buy to the spec (local supplier or CAD) |
| Belt tensioner bearings Dimensions are not documented; confirm in CAD before buying. | 9 bearings listed as 105RS in the workbook | 9 | Buy to the spec (local supplier or CAD) |
| Cable carrier Check the seller's inner/outer size convention and the end brackets. | 25 x 38 mm drag chain, 55 mm bend radius | about 1.5 m | |
| Electronics | |||
| Stepper motors NEMA17 on the Mini, not NEMA23. Check rear clearance for any alternative. | StepperOnline 17HS24-2104S: NEMA17, 60 mm body, 5 mm shaft, 2.1 A | 4 | |
| Stepper drivers Set the current to the NEMA17 motor (2.1 A). | StepperOnline DM542T or another DM542-class driver | 4 | |
| Controller GRBLHAL2000 takes 12 to 28 V; do not feed it from a 36 V motor supply. | GRBLHAL2000 or Flexi-HAL (grblHAL), or LinuxCNC with a Mesa card | 1 + a PC | Buy to the spec (local supplier or CAD) |
| Power supplies Size it from the actual motors and drivers; the workbook has no single wattage. | Motor supply matched to your drivers (24 or 36 V), control supply for the board | 1 or 2 | Buy to the spec (local supplier or CAD) |
| Homing and limit switches Both Y sides need their own switch for auto-squaring. | 6 mm normally-closed micro switches, or M8 NPN NC inductive sensors | 6 (2 X, 3 Y, 1 Z) | |
| Cabinet, E-stop, contactor Coil voltage and ratings to suit your supply. | Small cabinet with E-stop, start/stop and contactor | 1 set | |
| Cables Lengths from your routing. | Continuous-flex motor cable, shielded spindle cable, sensor cable, ferrules | 4 motor runs + spindle + sensors | |
| Spindle | |||
| Spindle or router Check body diameter, collet and Z reach. | 0.8 or 1.5 kW water-cooled 65 mm spindle with matched VFD, or a Makita RT0701C | 1 | |
| Mount and collets Pick collets from the spindle you bought. | 65 mm spindle mount, ER11 collets (ER16 if your spindle uses ER16) | 1 + collets | |
| Water cooling Only for a water-cooled spindle. | 75 W pump, 6 mm ID x 8 mm OD tubing (2 x 5 m), lidded reservoir | 1 set | |
| Hardware | |||
| Roller bolts and rods Plus the other M4/M5/M6 screws from the CAD. | 12 x M5 x 100 bolts, 6 x M5 x 120 threaded rod, 24 x M5 nyloc nuts, 4 x M6 x 1 grease fittings | as listed | |
| Tools | |||
| Drills, taps and crimper Supplier-cut stock and outsourced Z plates save tooling. | Metric hex keys, transfer punch, 4.2/5/6.5 mm drills, M5/M6 taps, ferrule crimper | 1 set | |
Based on: PrintNC Mini CAD and workbook, PrintNC wiki, Power supplies. Researched October 2026. "Search" buttons open a search for that exact spec, so compare listings against the spec and checks above; a price is only shown for an exact product found by model number. Some links earn us a commission at no extra cost to you (disclosure).