Identifying Saw Marks on Boards

Boards sawn on a sash sawmill have straight saw marks at a right angle to the length of the board. The key feature is that saw marks are very evenly spaced since the saw carriage moves a fixed amount between each saw stroke. The saw marks typically show spacing of 1/8 to 3/4 inch depending on the size of the log and the hardness of the wood (which varies with species and moisture content). Boards sawn on a bandsaw mill have straight marks similar to up-down saw marks. However, the spacing between marks from a bandsaw is more uneven than an up-down saw since the thin bandsaw blade can flex and then jump ahead more readily than a thick, rigid up-down blade. Sash-sawn boards are easily distinguished from the arcing saw marks on wood sawn by a circular sawmill.   We have been told by many neighbors of the Ledyard Sawmill that such marks can be seen on the lumber in their homes. When rough lumber is planed to make material for paneling, window frames, baseboards, etc., the sawmarks are usually removed from the surface that shows.

The saw marks on an old piece of lumber can give information about the type of mill that was used, but using the marks for dating the board needs to be done with great caution since periods in which different types of sawmills were used overlap by many decades in New England and elsewhere. Here in the southeast corner of Connecticut not far from Ledyard, the diary of Joshua Hempstead of New London, Connecticut mentions “saw pitts” in 1741, but also mentions sawmills as early as 1718 (and there is documentary evidence that the first sawmill in the New London area was built in the 1650s).


Boards sawn on an Up-down (Sash-type) sawmill have straight saw marks at a right angle to the length of the board. The saw marks are very evenly spaced since the saw carriage moves a fixed amount between each saw stroke. (1/8 inch between each stroke for this board sawn at the Ledyard mill.)

Up-Down saw marks typically show spacing of 1/8 (for hardwoods like this red oak board) to 1/2 inch (for soft woods like pine).

The marks on the right hand end of this board are the "stub shot" which show that the board was not sawn through the end of the log, but rather the last few inches were split off.  

Why not saw through the end of the log?  A wide piece is more stable on the head and tail blocks.  Individual boards are split off after the log is cut multiple times leaving a series of kerfs.







Boards sawn on an circular sawmill show the curved marks expected from a round saw blade.
   

  
Boards sawn on an bandsaw mill
 have straight marks similar to up-down saw marks. The spacing between marks from a bandsaw is more uneven than an up-down saw since the thin bandsaw blade can flex and then jump back more readily than a thick, rigid up-down blade. 

For these two bandsawn boards, the example on the left shows marks that are fairly even, but a close examination shows that the spacing is not identical. The example on the right is more clearly bandsaw with uneven spacing between the saw marks.