swing-stock

from The Century Dictionary.

• noun In flax-dressing, an upright piece of timber set in a foot-piece, and having a blunt edge at the top, over which flax is laid to be beaten with a sword-shaped wooden implement called a swingle, in the operation known as swingling, whereby the shives are beaten out of previously rotted and broken flax to separate the harl. This method has been superseded by modern flax-dressing machines. Also called swinging-block.