Flat sawing explained

Flat sawing, flitch sawing or plain sawing is a woodworking process that produces flat-cut or plain-cut boards of lumber.[1]

Process

After an initial cut through the diameter of a log, parallel cuts produce flitches: strips of lumber with consistent thickness.[2] Two cuts on each flitch trim the bark from the sides, and reduces it to a standard board width with squared edges. Two more cuts at each end set the length.

Lumber can be quickly flat-cut with a side-by-side set of mechanical saws.[3] A slower but sturdier method involves passing the log back and forth over a single saw.

To reduce buckling that may occur along the middle of flat-cut boards, the initial cut may be offset from the diameter, and resulting sections cut further before cutting the flitches.

Comparison

Flat-sawn wood often exhibits "flat-" or "slash grain", where the angle between the visible growth rings and the width of the board is 45° or less.[4] This makes the wood vulnerable to deformation as it dries, or if later exposed to moisture. Flat-sawn wood is less stable than quarter sawn or rift sawn wood, but can be produced more quickly and at lower cost.[5]

The face of the board may show curved grain, sometimes with intricate patterns.

Notes and References

  1. Book: Civil Engineering Materials. 382. Nagaratnam Sivakugan. Carthigesu T. Gnanendran. Rabin Tuladhar. M. Bobby Kannan. Cengage Learning. 2016. 9781337514606.
  2. Book: Band Saw Fundamentals. 77. Rick Peters. Hearst Books. 2006. 978-1-58816-522-0.
  3. How A Wind Powered Sawmill Works . Video . YouTube . May 10, 2016.
  4. Book: Architectural Woodwork Standards. Stanley R. (Rob) Gustafson. Glossary. Architectural Woodwork Institute (AWI), Architectural Woodwork Manufacturers Association of Canada (AWMAC), and Woodwork Institute (WI). 2014.
  5. http://www.hardwooddistributors.org/blog/postings/what-is-the-difference-between-quarter-sawn-rift-sawn-and-plain-sawn-lumber/ What is the difference between Quarter Sawn, Rift Sawn and Plain Sawn Lumber?