This video documents the craftsmanship of a Japanese carpenter building a straight staircase entirely from pine wood. The carpenter shares his detailed process, beginning with milling the raw timber and emphasizing the need to work quickly to prevent the pine from warping. He demonstrates his techniques for marking and cutting the stringers ("parent boards") and treads ("child boards"), including creating grooves 2mm narrower for a tight, durable fit. Key steps like building the landing first for accurate measurements, compressing wood for assembly, and using water to restore the fibers are shown. The project results in a 13-tread staircase with a unique landing design that provides access to two areas on the second floor.
How a Master Carpenter Builds a Pine Staircase
0:00 Project Introduction: The carpenter introduces the project: a 13-tread straight staircase made of pine, where the top step serves as a landing providing access to two different areas.
0:48 Material Preparation: He begins by milling rough-cut pine boards using a jointer, planer, and a large super surfacer. He stresses the need to work quickly as pine is prone to warping.
3:33 Importance of Timing: The grooves for treads and risers are cut immediately after milling. Waiting even 2-3 days can cause the timber to warp, making hand planing and precise fitting nearly impossible.
4:22 Precise Joinery Technique: To ensure a snug fit, the back edge of each tread (where the riser connects) is planed at a slight angle.
5:46 Building Sequence: The landing is always built first. This provides a fixed point, ensuring the measurements for the main staircase run are perfectly accurate.
7:30 Simplifying Stair Math: The carpenter notes that marking out a staircase is simple, requiring only the division of the total rise and run by the number of steps.
8:53 Test-Fitting is Crucial: Before cutting all the grooves into the stringers, he cuts only the top and bottom angles and test-fits them to confirm the length and fit, preventing costly mistakes.
10:41 Clean Cutting Technique: To prevent the wood grain from tearing, he first scores the outlines of the grooves with a utility knife before using a power tool to cut them.
12:40 The "2mm Rule" for a Tight Fit: The grooves in the stringers are intentionally cut 2mm narrower than the treads. This creates a friction fit that ensures the staircase remains solid and squeak-free over time.
16:29 Compressing Wood for Assembly: To fit the treads into the narrower grooves, he hammers their edges to temporarily compress the wood fibers. He notes that 1.5mm to 2mm is the ideal amount to compress without damaging the wood.
18:36 Restoring the Wood: After the treads are hammered into place, he applies water to the compressed edges. This causes the wood fibers to swell back to their original size, locking the joint tightly and restoring the wood's appearance.
18:53 Fine-Tuning the Risers: He describes fitting the risers as his least favorite part, requiring careful chiseling in tight spaces to get a perfect alignment with the treads.
20:42 Preventing Cracks: When securing components with screws, he applies glue around the screw holes and along the wood grain. This simple step effectively prevents the wood from splitting.