What Does "NEMA" Actually Mean? NEMA (National Electrical Manufacturers Association) sizes don't describe torque or power directly — they describe the faceplate dimensions of the motor. NEMA 17 means the mounting face is roughly 1.7 inches (42.3mm) square, while NEMA 23 means roughly 2.3 inches (57mm) square. This is why the number matters so much for CAD design — it directly determines your mount's bolt pattern and center bore size. Key Differences at a Glance - NEMA 17 - Faceplate: ~42.3mm x 42.3mm - Typical torque: 0.4–0.6 Nm - Common uses: 3D printers, small CNC routers, camera sliders - Bolt pattern: 31mm spacing, M3 screws - NEMA 23 - Faceplate: ~57mm x 57mm - Typical torque: 1.0–3.0 Nm - Common uses: larger CNC machines, industrial automation, heavier axis drives - Bolt pattern: 47.14mm spacing, M4/M5 screws The jump from NEMA 17 to NEMA 23 isn't just size — it's roughly 2–5x more torque, which matters a lot if your project involves heavier loads or longer travel distances. How to Decide Which One You Need Ask yourself these questions before choosing: 1. What's moving? Light axes (print heads, small sliders) rarely need more than NEMA 17. Heavy gantries or spindles usually need NEMA 23. 2. How much space do you have? NEMA 23 motors are noticeably bigger and heavier — this matters for portable or compact builds. 3. What's your budget? NEMA 23 motors and matching drivers typically cost more than NEMA 17 equivalents. If you're unsure, it's usually safer to slightly oversize the motor rather than undersize it — a motor working near its torque limit can skip steps under load. Designing the Mount in Fusion 360 Once you know which NEMA size you need, the mounting plate itself follows a standard pattern: - Match the bolt hole spacing exactly to the NEMA spec (31mm for NEMA 17, 47.14mm for NEMA 23) — even 0.5mm off can prevent the motor from seating flush. - Size the center bore to clear the motor's shaft boss, typically with 0.2–0.3mm clearance (see our [tolerance guide](/blog/3d-printing-tolerances-clearances-guide) for more on this). - Add mounting holes for the plate itself based on your frame or enclosure design. Rather than manually redrawing this for every project, our [NEMA 17](/scripts?category=motors-mounts) and NEMA 23 motor mount scripts let you generate a correctly-dimensioned plate in seconds by just entering your frame thickness and hole spacing — no need to look up the spec sheet every time. Quick Reference NEMA 17 — Faceplate: 42.3mm square • Bolt spacing: 31mm • Typical torque: 0.4–0.6 Nm • Screw size: M3 NEMA 23 — Faceplate: 57mm square • Bolt spacing: 47.14mm • Typical torque: 1.0–3.0 Nm • Screw size: M4/M5 Browse the full [Motors & Mounts category](/scripts?category=motors-mounts) to find the exact mount script for your motor size.