WORMGEAR.STUDIO

Step 1: Core Design

Worm Type: Cylindrical: standard, easy to manufacture. Globoid: hourglass shape, more contact area. Design Mode: Choose how to define your gear pair. "From Module" is the most common starting point. From Module is the standard starting point when you know the tooth size you need. From Centre Distance is useful when your shafts are already positioned. From Wheel OD constrains the wheel to fit a specific space. Envelope constrains both parts to fit within given outer diameters.

Module (mm): Tooth size. Standard modules: 0.5, 0.8, 1.0, 1.25, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0 The module is the fundamental tooth size in metric gearing: it equals the pitch diameter divided by the number of teeth. Larger modules mean bigger, stronger teeth but a larger overall gear. Standard modules (ISO 54) ensure tooling availability. For 3D printing, modules below 1.0 mm are difficult to print accurately with FDM. Ratio: Wheel teeth per worm start. Higher = more reduction. The ratio determines speed reduction and torque multiplication. A 30:1 ratio means the wheel turns once for every 30 worm revolutions. Typical values: 10-20 for power transmission, 30-60 for positioning mechanisms, 60-100 for precision instruments. The ratio also equals the number of wheel teeth divided by the number of worm starts.

Centre Distance (mm): Fixed shaft spacing between worm and wheel axes. Ratio: Wheel teeth per worm start. Higher = more reduction.

Wheel OD (mm): Maximum outer diameter of the wheel. Ratio: Wheel teeth per worm start. Higher = more reduction. Target Lead Angle (degrees): Lead angle affects efficiency. Below 3 deg = self-locking but low efficiency.

Arc Angle β (degrees): Controls hourglass curvature tightness (10°–180°). The arc angle (β) controls how tightly the hourglass curves. A large angle (e.g. 180°) produces tight curvature with a small radius, while a small angle (e.g. 60°) produces a gentler curve. This mode forces globoid worm type and uses the arc angle as a primary design parameter. Module (mm): Tooth size. Standard modules: 0.5, 0.8, 1.0, 1.25, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0 Ratio: Wheel teeth per worm start. Higher = more reduction.

Worm OD (mm): Maximum outer diameter of the worm. Wheel OD (mm): Maximum outer diameter of the wheel. Ratio: Wheel teeth per worm start. Higher = more reduction.

Treat ODs as maximum constraints (find largest standard module that fits)

Number of Starts: 1 = self-locking at low lead angles. 2-4 = higher speed, no self-locking. The number of starts (threads) on the worm controls the lead angle and self-locking behaviour. A single-start worm has the lowest lead angle and is most likely to be self-locking — meaning the wheel cannot back-drive the worm, useful for lifting applications. Multi-start worms (2-4) have steeper lead angles, higher efficiency (less friction), but lose self-locking. The number of wheel teeth must be divisible by the number of starts. Pressure Angle (degrees): 20 deg is standard (DIN 3975). 14.5 deg for legacy, 25 deg for high strength. The pressure angle defines the slope of the tooth flanks. It affects the direction of force between meshing teeth. 20° is the modern standard (DIN 3975) and gives a good balance of strength and smooth running. 14.5° was the historical standard and produces smoother, quieter operation but weaker teeth. 25° creates stronger teeth that can carry more load but increase bearing forces and noise. Hand: Right-hand is standard. Left-hand for special arrangements. A right-hand worm has threads that spiral clockwise when viewed from the end, like a standard screw. This is the convention for most worm gears. Left-hand worms are used when the direction of output rotation matters, or in paired arrangements where opposing hands cancel axial thrust forces on the worm shaft bearings.

Step 2: Advanced Gear Options

Tooth Profile (DIN 3975): ZA: straight flanks, standard for CNC. ZK: convex flanks, better for 3D printing. ZI: involute, high precision hobbing. The tooth profile defines the cross-sectional shape of the worm thread. ZA (straight/trapezoidal) has straight flanks in the axial section — standard for CNC machining because it can be cut with a lathe tool. ZK (convex) has slightly curved flanks that reduce stress concentrations at the tooth root, making it better for 3D printing where layer adhesion and fatigue life matter. ZI (involute) is the highest precision profile, typically produced by hobbing machines and matching a standard involute gear cutter. Backlash (mm): Clearance between meshing teeth. 0.05 mm typical for precision. 0.1-0.2 mm for 3D printed parts. Backlash is the intentional gap between meshing teeth when there is no load. It compensates for thermal expansion, manufacturing tolerances, and provides space for lubricant. Zero backlash sounds ideal but causes binding, excessive wear, and heat buildup. 0.05 mm suits precision CNC-machined gears with good surface finish. 3D printed gears typically need 0.1-0.2 mm due to layer roughness and dimensional accuracy limits of FDM/SLA processes. Profile Shift Coefficient: Adjusts tooth depth to prevent undercut on low tooth counts. Positive = thicker teeth. Profile shift modifies the tooth proportions by shifting the cutting tool position relative to the gear blank. A positive shift produces thicker, stronger teeth and avoids undercut on gears with few teeth (typically below 17 teeth for 20° pressure angle). A negative shift produces thinner teeth with deeper roots. For most worm gears, zero profile shift is standard. Only adjust this if the calculator warns about undercut or if you need to fine-tune the centre distance.

Round to nearest standard module (ISO 54)

Stub teeth (reduce wheel tip)

Throated wheel teeth (better contact)

Shape wheel teeth to match worm curvature. Better contact area, requires hobbing or 5-axis machining. A throated wheel has teeth that wrap around the worm, creating a larger contact area and spreading the load across more teeth simultaneously. This increases load capacity significantly but requires more complex manufacturing: either a hobbing machine with the correct hob, or 5-axis CNC machining. Non-throated (spur/helical) wheels only contact the worm at a single point, limiting load capacity but simplifying manufacturing.

Worm Length and Wheel Width

Use auto-calculated dimensions (uncheck to customize)

Step 3: Bore & Shaft Interface

Worm Shaft

Bore: Auto sizes bore to ~25% of pitch diameter with standard rounding. The bore is the central hole through the gear for mounting on a shaft. Auto-calculation sizes it to approximately 25% of the pitch diameter, then rounds to a standard shaft size. The bore must be smaller than the root diameter to leave enough material for the teeth. Solid (no bore) is useful for prototyping or when you plan to machine the bore separately.

Recommended: --

Wheel Shaft

Bore: Auto sizes bore to ~25% of pitch diameter with standard rounding.

Recommended: --

Relief Grooves

Add relief grooves at worm thread ends

Undercuts at worm thread ends for manufacturing clearance.

Waiting for calculation...

Enter parameters to calculate design

Loading generator...

Design Summary

No design loaded. Use a Design tab or upload JSON.

Console Output

Ready to generate geometry...

Worm Thread Method: Sweep: ~25x faster, clean topology. Loft: original method, creates sections and lofts between them. Wheel Generation Method: Helical: fast, simple geometry. Virtual Hobbing: simulates real hobbing for accurate tooth throating. Much slower.

Generates worm and wheel STEP files

Includes: worm.step, wheel.step, worm.3mf, wheel.3mf, assembly.glb, worm.stl, wheel.stl, design.json, design.md

You can also generate STEP files from the command line:
pip install wormgear then wormgear design.json

Generate 3D models first, then return here to see the animation.