Terms of use

Using the gear design tool

About the service

Involute CAD is a browser tool for designing external spur gears and internal ring gears, exploring gear-train motion and exporting meshes for prototyping. These terms describe the free public beta. The public email appears on the contact page; the operator is Tyrone Charlton. Applicable address disclosures remain under review. Access is free. No purchase or subscription is required. Optional tips to Tyrone Charlton are handled by PayPal. This version has no advertising, sponsorship or affiliate revenue. There is no age restriction. Children should ask a trusted adult for help with physical fabrication and machinery; use of the website does not certify a design as safe.

Engineering limitations

The tool is not a substitute for professional engineering review. It uses involute tooth flanks with simplified radial root relief and kinematic motion. It does not determine load capacity, fatigue, material strength, manufacturing tolerances, every possible assembly collision or fitness for a safety-critical application.

Ring-pair interference and placement checks cover supported cases and use sampled profiles or conservative envelopes. They are not a complete collision or physical dynamics simulation; planetary centres do not orbit. A closed-mesh check is not a safety certificate. Check dimensions and units in your slicer, verify clearances and gear engagement, and test a prototype before relying on it. Do not rely on this tool alone for machinery where failure could injure someone or damage property. Keep hands and loose items clear of physical moving gears.

Your projects and permitted use

You retain any rights you hold in designs and information you enter. Involute CAD does not claim ownership of your exported gears. You may use exports for personal or commercial projects, subject to applicable law and other people’s rights. You are responsible for checking any patent, design, copyright or other rights relevant to your use.

Use the service lawfully. Do not disrupt its operation, attempt unauthorised access, distribute malicious files through it, or misrepresent tool output as independently certified. Third-party software remains subject to its own licence; see the bundled Three.js licence and the Manifold licence.

Saving work and availability

Save your project before closing or refreshing the editor. This version does not provide cloud backup. Features may be corrected, changed or unavailable. Reasonable care is taken in development, but the preview is not promised to be error-free or continuously available.

Your legal protections

Nothing in these terms excludes or limits liability for death or personal injury caused by negligence, fraud or fraudulent misrepresentation, or any liability that cannot lawfully be excluded or limited. Your mandatory consumer rights and any mandatory protections of your home jurisdiction are preserved.

These terms do not require you to waive statutory rights or use a particular foreign court. The absence of a fee does not remove any legal rights or obligations that apply.

Optional tips and downloads

STL and OBJ downloads start after a fixed 10-second countdown. Tipping is completely optional and does not shorten the countdown. PayPal opens separately, where you choose an amount and confirm payment. The editor does not collect card details or check payment status. PayPal eligibility rules, terms and any applicable fees apply.

For a mistaken tip or refund enquiry, email involutecad@gmail.com with the transaction reference, not your card details. Requests are reviewed individually; nothing here limits mandatory legal rights or PayPal dispute rights.

Shafts, bearings and gearbox housings

Housing clearances use rotating gear envelopes and simple geometric checks. Bearing models are reference rings; they are not functional rolling bearings. Split casing halves have no designed fasteners or alignment features. The tool does not calculate shaft stress, bearing life, lubrication, heat, material shrinkage or structural loading. Inspect exported parts and verify fits with test prints before physical use.

Privacy, no-ad policy and updates

The application sets no cookies and uses no analytics, tracking pixels or advertising services. The privacy and cookie notices explain OpenAI Sites hosting and distinguish platform processing from this application. See Funding & no-ad policy and the privacy notice. The date on this page identifies this revision; material changes should be made clear when the service changes. For concerns or errors, email involutecad@gmail.com.