Patent Application
20090120255
1. Field of the Invention
This invention relates to a fence device for a cutting machine, more particularly to a fence device with a micro-adjusting mechanism for precisely positioning a fence.
2. Description of the Related Art
A fence device is generally used for positioning a workpiece on a tabletop of a cutting machine, such as a table saw. The fence device extends across the tabletop, and is movable longitudinally so as to define a desired cutting length of the workpiece, i.e., the distance between the fence device and a circular saw. Micro-movement of the fence device is required when the cut length of the workpiece is quite close to the desired cutting length. Hence, a micro-adjusting mechanism is provided to move the fence device through a small distance for precise adjustment.
Referring to
The object of the present invention is to provide a micro-adjustable fence device for a cutting machine, which can be easily operated to apply an even frictional force to a guiding rail for micro-adjustment of the position of a fence.
According to this invention, the micro-adjustable fence device includes a fence which has front and rear ends and which is movable in a longitudinal direction, and a carriage which is mounted to the fence proximate to the front end. The carriage has a chassis body which has a major wall surface confronting a guiding rail of a cutting machine. The major wall surface extends in a first transverse direction and forwardly of the guiding rail to terminate at a fore end. The major wall surface has a riding route therein which extends in the longitudinal direction to guide the major wall surface to slidably ride on the guiding rail so as to permit movement of the fence. A wheel includes a hub which is rotatably mounted relative to the chassis body about a rotating axis in a second transverse direction, and which defines a hub center in the rotating axis, and a rim which is manually turnable about the rotating axis, and which is disposed to be shiftable between a traction gaining position, where the rim frictionally contacts the guiding rail at a tangential point so as to roll thereon, and an idle position, where the rim is disengaged from the guiding rail. The tangential point is in line with an advancing path of the hub center when the rim shifts from the idle position to the traction gaining position. A biasing member is disposed to bias the hub to move towards the idle position.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment of the invention, with reference to the accompanying drawings, in which:
Referring to
With reference to
The carriage 21 is mounted to the fence 22 proximate to the front end 221, and has a chassis body 210 which has a handle 212 and a downwardly facing major wall surface 218 disposed at upper and lower portions, respectively. The major wall surface 218 is adapted to confront the front guiding rail 120 in a second transverse direction transverse to both the first transverse direction and the longitudinal direction. The major wall surface 218 extends in the first transverse direction and forwardly of the front guiding rail 120 to terminate at a fore end 219. A front upright wall 213 extends in the second transverse direction from the fore end 219, and has an operating opening 2131 formed therethrough. A partition wall 217 extends from the major wall surface 218 in the second transverse direction such that the partition wall 217 cooperates with the major wall surface 218 to define a riding route 211 that extends in the longitudinal direction to guide the major wall surface 218 to slidably ride on the guiding rail 120 so as to permit movement of the fence 22 in the longitudinal direction. Additionally, the partition wall 217 cooperates with the front upright wall 213 to define a mounting chamber 216 for receiving the micro-adjusting mechanism 5. The partition wall 217 has a passage 2171 which extends therethrough in the first transverse direction to communicate the mounting chamber 216 with the riding route 211.
The major wall surface 218 in the mounting chamber 216 further extends in the longitudinal direction to terminate at left and right sides. A tubular post 214 is disposed in a central area of the mounting chamber 216, and has a guiding slot 2141 which extends along an advancing path that defines a straight line in the first transverse direction and normal to the riding route 211. Two anchoring posts 215 are disposed at front and rear sides of the major wall surface 218, and are equally distant from the tubular post 214.
The micro-adjusting mechanism 5 includes a wheel 30, a biasing member 40, and a cover plate 50. The wheel 30 includes a spindle 31 which extends in the second transverse direction, a hub 33 which surrounds the spindle 31 and which defines a hub center in a rotating axis in the second transverse direction, and a rim 32 which is manually turnable about the rotating axis. The spindle 31 extends outwardly of the hub 33 to form a key end 311 that is rotatable and that is guided to move in the guiding slot 2141. The rim 32 is configured to be serrated, and extends beyond the front upright wall 213 through the operating opening 2131 to facilitate operation.
The biasing member 40 is a wire spring 40 which has two secured ends 41 that are respectively secured to the anchoring posts 215, and a middle biasing portion 42 that is interposed between the secured ends 41 and that engages the hub 33 so as to bias the hub 33 away from the guiding rail 120.
The cover plate 50 is disposed to cover the mounting chamber 216, and is secured to the anchoring posts 215 by means of two screw fasteners 52. The cover plate 51 has a guiding hole 512 which extends therethrough and along the advancing path such that the spindle 31 extends through and is movable relative to the guiding hole 512.
Referring to
As illustrated, since the wheel 30 is disposed in a middle area of the mounting chamber 216, and since the hub 33 is engaged with the middle biasing portion 42 of the biasing member 40, the user can operate the portion of the rim 32 that extends beyond the operating opening 2131 so as to move the hub center along the straight advancing path, rather than along an angular path like that of the aforesaid conventional wheel 13. Thus, the tangential point 321 of the rim 32 is in line with the advancing path of the hub center when the rim 32 shifts from the idle position to the traction gaining position. Subsequently, the user can rotate the rim 32 at the portion which extends beyond the operating opening 2131 to move the entire fence device along the guiding rails 120 to a desired position of adjustment. Thus, the micro-adjusting operation is easy to conduct. Additionally, the force generated as a result of the micro-adjusting operation of the wheel 30 can be evenly applied to the carriage 21 to prevent tilting of the carriage 21, thereby resulting in smooth movement of the fence device along the guiding rails 120. Moreover, the biasing force of the biasing member 40 can evenly bias the wheel 30 due to engagement of the middle biasing portion 42 with the hub 33. While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretations and equivalent arrangements.
