목공 문제: 목재 팽창 및 수축

The success of a woodworking project depends partly on whether you’ve allowed for wood expansion and shrinkage. Wood moves as it releases or absorbs moisture. That’s why it makes no sense to use freshly cut wood for a project: the wood will shrink significantly as it dries.

A living tree is full of moisture because many gallons of water move through it every day, from the roots to the branches and leaves, and some of that moisture is released into the atmosphere. The relationship between wood and the moisture in its environment continues after a tree is cut down. Wood adapts to the moisture level around it by either releasing moisture, which causes shrinkage, or absorbing moisture, which causes expansion.

평형을 이루기 위한 마른 나무

Most lumber manufacturers use kilns to dry lumber to the proper moisture levels for woodworking. Kiln drying uses heat to dry stacks of lumber. Lumber can also be air-dried, but the process is much slower. Handheld wood moisture meters make it easy to check the moisture level in a piece of lumber.

The goal is to dry wood to the moisture level it will reach in the environment where the finished product will be used or installed. Matching the wood to that environment, its equilibrium moisture content, minimizes movement.

Changes within an environment can still cause problems. In the upper Midwest, for example, summers are humid but winters are quite dry. Many homeowners use humidifiers in winter to add moisture back to the air so hardwood floors and furniture don’t dry out enough to be damaged. This kind of seasonal change in humidity is why dresser drawers and doors tend to stick in summer but work fine in winter.

Moving a piece of furniture to a very different climate is another consideration. A finely crafted hardwood chest of drawers that has reached equilibrium in a humid place like Louisiana could crack if it’s moved to a dry climate like Arizona, as the wood releases a substantial amount of moisture.

나무가 어떻게 팽창하는지 이해하세요

A skilled woodworker knows how the wood being used will move as it adjusts to the moisture in its environment. Almost all of that movement happens across the grain, not along it. Shrinkage along the grain from green to oven-dry is only about 0.1% to 0.2% for most species, according to the USDA Forest Products Laboratory’s 목재 핸드북. In other words, an 8-foot-long 2×4 will stay essentially 8 feet long, but its width and thickness can change significantly.

무료 다운로드 – 목재 프로젝트가 실패하는 6가지 이유

확장을 염두에 두고 구축하세요

If you’re building a cabinet, for example, it can help to use wood from the same original stock. In any case, orient the grain of the lumber in the same direction. Wood movement can affect drawers and make them hard to open. That’s one reason plywood is used for most cabinet carcasses: its alternating grain layers make it much more dimensionally stable along its length and width than solid lumber.

When you glue boards together for a tabletop, many woodworkers alternate the orientation of the growth rings on the end grain, with one board’s rings curving up and the next board’s curving down. If the boards cup, each one cups slightly in the opposite direction instead of the whole top cupping as one. Starting with properly dried wood is still the best way to limit cupping.

왜 이것을 아는 것이 중요한지 알아보세요 목공 프로젝트에 적합한 수분 함량.

오리온 수분계 구매

론 스미스

Wagner Meters의 영업 관리자인 Ron은 다양한 산업 분야에서 계측 및 측정 시스템 분야에서 35년 이상의 경력을 보유하고 있습니다. 이전에는 지역 영업 관리자, 제품 및 프로젝트 관리자, 그리고 계측 계측 관련 제조업체의 영업 관리자를 역임했습니다.

최종 업데이트 날짜: 8년 2026월 XNUMX일