how does frost make the saw appear sinister
Frost uses several techniques to ensure that the saw appears sinister and threatening in "'Out, Out--.'" First, "snarled and rattled," the sounds made by the saw, are repeated; they suggest a dangerous animal with "snarled" as well as the mechanical nature of the saw with "rattled." Will the beast attack? Is the saw somehow loose? The saw, furthermore, is given life with the verse, "as if to show saws knew what supper meant, /Leaped out at the hand, or seemed to leap--." Here the saw is depicted as a hungry creature that seems to attack the boy's hand, viewing it as supper.
The dangerous image of the saw is also suggested in the beginning of the poem with Frost's description of the setting: "from there those that lifted eyes could count / Five mountain ranges one behind the other/ Under the sunset far into Vermont." The scene foreshadows two images: first, the five mountain ranges suggest five fingers, red under the sunset--a bloody hand. Second, the sharp teeth of the saw are similarly suggested by the mountaintops glowing red under the sunset.