"This door must satisfy three core requirements: its sealing must be good enough to isolate cold air to the maximum extent."

"It must be robust enough to withstand the gales of the Labrador Coast, and even endure the probing of a curious black bear."

"Without modern metal hinges and nails, its rotating structure must be simple, reliable, and durable."

"I will adopt a design I call 'cross-pin hinge.'"

"All of its weight-bearing relies on a few sturdy wooden pins and slots, completely eliminating the need for a complex pivot, making it easier to construct."

"But to achieve this design, I need to perform some relatively precise drilling work. Therefore, I must upgrade my toolbox before making the door."

"I plan to create something less labor-intensive—a pump-style hand drill."

Facing the camera, he explained: "Its structure is more complex than that of a bow drill. It requires making a drill rod, a crossbar, a flywheel, and a handle."

"Once completed, I just need to press up and down with one hand to achieve a more stable and faster rotation than a bow drill. This will greatly save my energy and time."

Lin Yu'an once again turned and walked into the silent forest covered by white snow.

His first task of the day was to craft this crucial tool, which could be regarded as primitive 'machinery,' for himself.

He first needed a straight, hard, and dried piece of wood as the core of the whole apparatus—the drill rod.

After searching, he found a straight section of a branch on a long-fallen, partly debarked dead birch tree, and cut it with a handsaw.

Then he returned to the shelter and began the detailed carving work.

Clamping the rough log between his legs, he used a hand axe to chop off the excess in broad strokes, roughly shaping it into a square column. 𝗳𝚛𝚎𝚎𝘄𝕖𝕓𝕟𝕠𝚟𝚎𝕝.𝗰𝕠𝐦

Then, he switched to the sharp Damascus Hunting Knife for finer work.

Shaving off the four edges of the square column bit by bit, he frequently rolled the wooden rod on a flat stone slab, bringing it close to his eyes to check for any unevenness, then used the knife blade to gently scrape.

Finally, a straight and smooth cylindrical wooden rod, about half a meter long and four centimeters in diameter, appeared in his hands.

Afterward, with the tip of his knife, he etched a faint, evenly spaced spiral mark on the upper half of the rod, ring by ring.

This was a draft; if he carved incorrectly, the entire drill rod might be ruined. He repeatedly checked the angle and spacing of the spiral, confirming everything was correct before starting the formal carving.

With knife tip against the shallow groove, he gradually carved downward.

Sawdust curled off from the knife's edge, and the spiral groove slowly took shape under his hands.

This process took him over an hour to finally carve a deep and perfect spiral groove capable of guiding cord movement.

Lastly, he shaped the lower end of the wooden rod into a thicker and blunter drill bit shape and carefully roasted it repeatedly in the fireplace's embers, carbonizing its surface to harden it and enhance its cutting capacity.

The top end was carved to be thin and smooth, reducing friction; an impeccable drill rod was thus completed!

Next was making the crossbar, the 'pump' handle which could slide up and down.

He found a thick, rectangular hardwood plank and needed to create a smooth hole slightly larger than the drill rod in its center.

This time, Lin Yu'an had to resort to the primitive "burn-drill method."

He stood the wooden plank on the ground and used the knife tip to carve deep crisscross marks in the center as a locator.

Then, going to the fireplace, he used two sharpened sticks as chopsticks to pick up a walnut-sized piece of glowing embers from the coals.

He returned briskly and precisely placed this hot ember on that cross-marked spot.

Then bending down, he brought his mouth close to the ember's base and continuously blew air.

"Hoo—hoo—"

With the infusion of fresh oxygen, the ember's temperature rose sharply, changing from dark red to a dazzling orange-red!

It began burning downward like a miniature furnace, charring the underlying wood, and a potent scorched scent filled the air.

When the ember's temperature slightly decreased, he nudged it aside with the knife tip and scraped away the charred, friable wood residues from the hole.

Burn, blow, clean... he repeated this cycle continually.

After over half an hour of operations, a smooth, dark hole appeared precisely at the wooden plank's center.

Then he started crafting the inertia-adding flywheel.

On the lower part of the drill rod, he first carved out a shallow slot.

Next, from another thicker segment of birch wood, he sawed a roughly ten-centimeter thick, disc-like round wood piece, then used the "burn-drill method" to burn a hole in its center.

He forcefully fitted this heavy round wood piece onto the drilled rod's lower half until it reached the slot.

He then shaped several small, sturdy wooden wedges, coated them with pine resin, and hammered them into the gap between the round wood piece and the drill rod from all sides, 'dinging' them firmly in place so there wouldn't be the slightest wobble.

This counterweight wheel, akin to a gyroscope base, was crucial for maintaining the drill rod's continuous rotation and automatic resetting.

Finally, he securely tied one end of a durable rope in the groove at the top of the drill rod, with the other end passed through small holes at both ends of the crossbar and tied tight.