Patent Application
20080041495
The following detailed description, given by way of example and not intended to limit the present invention solely thereto, will best be appreciated in conjunction with the accompanying drawings, wherein like reference numerals denote like elements and parts, in which:
The instant invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these illustrated embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Routers and router bits have long been used for cutting various profiles and configurations along the edges of work pieces composed of wood or other materials. These profiles and configuration include bevels, chamfers, roundovers, ogees, coves, etc. The instant invention relates to a router bit that is used to cut tenons in a work piece for use in mortise and tenon joinery. More specifically, the instant invention relates to a router bit that has variably spaced cutters that allow the distance between the cutters to be increased or decreased in order to change the thickness of a tenon that is being cut with the router bit.
In the following description, like reference characters designate like or corresponding parts throughout the figures. Additionally, in the following description, it is understood that terms such as “upper,” “lower,” and the like are words of convenience and are not to be construed as limiting terms.
Referring now to the figures,
As depicted in the figures, each cutter comprises a body portion 28 and cutter blades 30. Preferably, one pair of diametrically opposed cutter blades 30 are secured to the body portion 28, however as will be apparent to those skilled in the art, any number of cutter blades 30 may be secured to the body portion 28. The cutter blades 30 are spaced about the circumference of the body portion 28 so as to assist in balancing the weight of the router bit 2 in all radial directions. As depicted in
The body portion 28 and the arbor 4 may be manufactured from steel and the cutter blades 30 may be manufactured from carbide, high strength steel (HSS) or some other wear-resistant material. In order to increase the performance of the instant router bit, the exterior surface of the body portion 28 is coated with a friction-reducing material. The friction-reducing material may be, for example, a polymer having friction-reducing capabilities, such as, but not limited to fluorocarbon polymers. Preferred fluorocarbon polymers include tertrafluoroethylene (TFE) and polytetrafluoroethylene (PTFE) fluorocarbon polymers and fluorinated ethylene-propylene (FEP) polymers. In the instant embodiment of the invention, the PTFE coating is an orange PTFE coating. Because the PTFE coating reduces friction, the router bit performs better, lasts longer and cleans up quicker.
As described below and as depicted in
Turning now to the set up and use of a router bit according to the instant invention, once a user determines the thickness of a tenon to be cut, the user chooses the required combination of spacers and shims to be disposed between the lower and upper cutters. For example, as depicted in
After the router bit 2 is assembled with the lower and upper cutters, 52 and 54 respectively, and the desired number of spacers and shims, a user secures all of the elements in position on the arbor by threadingly engaging the nut 22 with the threaded shaft portion of the arbor 4. Once the nut 22 is tightened down, thereby securing all elements in a rotationally-fixed position on the shaft portion 8 so that all of the elements rotate as a single structure, the router bit 2 is placed in a table-mounted router and is now ready for user. In addition to assembling the instant router bit prior to placement in a router, the bit may first be placed in a router and then assembled while in the router following the previously disclosed assembly steps. If after the user performs test cuts on the material and the lower cutters to upper cutters spacing is not set to produce the exact tenon thickness desired, shims varying in thickness from 0.1 mm to 0.3 mm may be added to the router bit between the lower and upper cutters to obtain the desired tenon thickness. Once the desired tenon thickness is obtained, bit setup is complete. Advantageously, once the instant router bit is set to produce tenons of the desired thickness, all tenons cut using the same set up will have the exact same tenon thickness regardless of variations in the material thickness or down pressure applied to the work piece.
As will be apparent to those skilled in the art, in additional embodiments of the instant invention, the number of lower and upper cutters can be increased or decreased depending on the thickness of the material being cut. That is, a single lower and a single upper cutter may be used instead of a pair of lower and upper cutters or more than two lower and two upper cutters may be used. Furthermore, the number of lower cutters does not have to be the same as the number of upper cutters. If additional cutters are used, an arbor having a shaft portion with an increased length will be necessary.
Although a preferred embodiment of the present invention and modifications thereof have been described in detail herein, it is to be understood that this invention is not limited to this precise embodiment and modifications, and that other modifications and variations may be effected by one skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
