A fence post jig assembly includes a frame that has a plurality of intersecting sides such that the frame defines a rectangle. In this way the frame can be positioned around a fence post. The frame has a lip extending outwardly therefrom and the lip extends around each of the intersecting sides. Thus, the lip defines a guide surface that is oriented on a horizontal plane when the frame is positioned around the fence post. Moreover, the guide surface can guide a saw to cut the fence post along the horizontal plane thereby enhancing precision of cutting the fence post. A plurality of screws each extends through a respective one of the intersecting sides of the frame and each of the screws extends toward a center of the frame when the screws are tightened. In this way each of screws can engage the fence post for retaining the frame on the fence post at a desired height on the fence post.

A saw contains: a saw blade, a handle, and an auxiliary fixing device. The saw blade includes a serrated sawing section, a connection shaft, a fixing post defined between the connection shaft and the handle. The auxiliary fixing device includes two clamp extensions, wherein two front ends of the two clamp extensions are connected together by using a guiding section of the auxiliary fixing device. The auxiliary fixing device also includes two first elastic rings respectively rolled on two rear ends of the two clamp extensions, two second elastic rings individually formed in the two first elastic rings. Each second elastic ring is eccentric with each first elastic ring and its diameter is less than that of each first elastic ring, each second elastic ring is rotatably fitted with the connection shaft, and each first elastic ring abuts against the fixing post as not using the saw.

A saw contains: a saw blade, a handle, and an auxiliary fixing device. The saw blade includes a serrated sawing section, a connection shaft, a fixing post defined between the connection shaft and the handle. The auxiliary fixing device includes two clamp extensions, wherein two front ends of the two clamp extensions are connected together by using a guiding section of the auxiliary fixing device. The auxiliary fixing device also includes two first elastic rings respectively rolled on two rear ends of the two clamp extensions, two second elastic rings individually formed in the two first elastic rings. Each second elastic ring is eccentric with each first elastic ring and its diameter is less than that of each first elastic ring, each second elastic ring is rotatably fitted with the connection shaft, and each first elastic ring abuts against the fixing post as not using the saw.

A saw contains: a saw blade, a handle, and an auxiliary fixing device. The saw blade includes a serrated sawing section, a connection shaft, a fixing post defined between the connection shaft and the handle. The auxiliary fixing device includes two clamp extensions, wherein two front ends of the two clamp extensions are connected together by using a guiding section of the auxiliary fixing device. The auxiliary fixing device also includes two first elastic rings respectively rolled on two rear ends of the two clamp extensions, two second elastic rings individually formed in the two first elastic rings. Each second elastic ring is eccentric with each first elastic ring and its diameter is less than that of each first elastic ring, each second elastic ring is rotatably fitted with the connection shaft, and each first elastic ring abuts against the fixing post as not using the saw.