Egyptian saws, so far as has yet been discovered, are single-handed. As is the case in modern Oriental saws, the teeth usually incline toward the handle, instead of away from it like ours. They have, in most cases, bronze blades, apparently attached to the handles by leathern thongs. No evidence exists of the use of the saw applied to stone in Egypt, but we read of sawn stones used in the temple. (1 Kings 7:9) The saws "under" or "in" which David is said to have placed his captives were of iron. The expression in (2 Samuel 12:31) does not necessarily imply torture, but the word "cut" in (1 Chronicles 20:3) can hardly be understood otherwise.
Saw
2 verses
2 Samuel
2 Samuel 12:31
And he brought forth the people that were therein, and put them under saws, and under harrows of iron, and under axes of iron, and made them pass through the brickkiln: and thus did he unto all the cities of the children of Ammon. So David and all the people returned unto Jerusalem.
Isaiah
Isaiah 10:15
Shall the axe boast itself against him that heweth therewith? or shall the saw magnify itself against him that shaketh it? as if the rod should shake itself against them that lift it up, or as if the staff should lift up itself, as if it were no wood.
From Smith's Bible Dictionary
William Smith, 1884