Helical Gear Calculator

When to use this CAD/mechanical design tool

• Use for helical gear CAD layout.
• Use when moving from normal-module data to transverse geometry.
• Use before shaft, bearing, housing, and supplier review.

How to use

1. Enter one mechanical-design case using typed dimensions, counts, RPM values, tolerances, or drafting selections.
2. Click the exact action button for the selected tool; default values, typing, URL-prefilled values, and worked examples do not generate results automatically.
3. Review the output cards, warnings, assumptions, visual summary, copy text, and downloads before using the result in CAD, drawing, supplier, or inspection workflow.
4. Verify final values against applicable standards, supplier catalogs, validated CAD documentation, manufacturing limits, inspection practice, and qualified engineering review.

Input guide

Normal module or normal DP

Basis used before correcting for helix angle.

Helix angle

Angle used to convert normal geometry to transverse geometry.

Paired gear teeth

Optional paired tooth count for center-distance planning.

Notation

Output interpretation

• Transverse basis controls pitch diameter.
• Helix angle increases pitch diameter for a fixed normal module.
• Center distance is preliminary and requires mating gear compatibility review.

Supported CAD/mechanical design use cases

• Simple external helical gear geometry
• Normal-to-transverse conversion
• Paired center-distance estimate

Unsupported patterns

• Crossed helical gears
• worm gears
• axial thrust sizing
• contact stress
• manufacturing cutter selection

How to interpret the output

• A higher helix angle increases transverse module.
• Center distance uses transverse pitch diameters.
• Bearing loads and thrust are not calculated.

CAD and mechanical-design guidance

• Confirm helix hand for mating gears.
• Review axial thrust and bearing capacity.
• Verify normal pressure angle and supplier tooth system.

Worked examples

Assumptions

• Inputs are typed planning values and are not extracted from CAD files, supplier catalogs, drawings, PLM, CAM, ERP, or inspection systems.
• Metric calculations use millimetres unless the output explicitly states another unit; inch calculations use inches unless the output explicitly states another unit.
• The result is a preliminary calculator or drafting helper and not a certified standards database, CAD kernel, inspection report, or supplier approval.
• Normal module or normal DP is used as the starting basis.
• Helix angle is between zero and forty-five degrees for this planning model.

Practical guidance

• Compare with Spur Gear Calculator to see helix-angle effect.
• Use Shaft Key Calculator when torque transfer through the hub matters.

Common mistakes

• Using normal module directly as transverse module.
• Ignoring helix hand.
• Forgetting axial thrust and bearing review.

Limitations

• No tooth strength, axial thrust, overlap ratio, profile shift, backlash, lubrication, or noise calculation is included.
• ScholarTool CAD and mechanical-design calculators provide general engineering calculation and planning support. They do not replace supplier requirements, certified standards, CAD software documentation, manufacturing review, inspection standards, or professional engineering judgement.
• The tool does not open, upload, parse, repair, or validate CAD files, drawings, STEP, STL, DXF, DWG, CAM, or CNC data.
• The tool does not perform strength certification, fatigue validation, finite-element analysis, supplier catalog selection, standards compliance certification, or inspection programming.

Related workflow links