You can freely build on The Invention of Lincoln Logs

What this patent covers

The patent describes a system of wooden logs with notches cut into them at specific intervals. These notches allow the logs to be stacked perpendicularly to create interlocking walls for toy structures like cabins or forts. The design relies on the gravity-fed friction of the notches to keep the walls stable without needing glue or nails. It provides a modular method for children to build three-dimensional structures that look like miniature log cabins.

What is now free to use

All 0 claims of US 1351086 are in the public domain. Specifically:

The 0 dependent claims add narrowing limitations and are also free.

What is NOT covered

Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.

• Does not cover building systems that use plastic bricks or studs like LEGO.

• Does not cover non-notched construction sets or blocks that rely solely on stacking without interlocking joints.

• Does not cover structural designs for full-sized, habitable buildings.

Who is building on this today

The Lincoln Logs brand is currently owned by Basic Fun!, which continues to produce sets based on the original interlocking log concept. The modular construction principle remains a staple in the educational toy market.

Products built on expired version of this technology

How to cite this patent in your documentation

Individual. US Patent 1351086. Toy-cabin construction. Granted 1920, expired 1940. Now in the public domain.

Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.

PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.