1. Field
This application relates to the technical field of portable power tool guards, specifically guards for hand held portable routers.
2. Prior Art
Typically basic original equipment router bases and sub bases are provided attached to the router motor. The router base supports the motor and the sub-base is attached to the bottom of the router base. The sub-base provides a smooth, flat work contacting surface which permits the router to slide easily upon the work as the operator advances a rotating router bit along a workpiece. The sub-base also provides a smooth side edge surface which can be slid against a straight edge or template edge to encourage the machine to accurately follow a predetermined cutting path. Some routers do not have a sub-base, instead some manufacturers for example RYOBI use the bottom surface of the base itself as the surface which contacts the workpiece. Optional bases, sub-bases or base attachments also exist which allow the router to perform various dedicated operations for example adjustable circle cutting, adjustable dado cutting, under-scribing and seaming, and more relevant to the present invention chip deflection and dust extraction. One such prior art base option is disclosed in U.S. Pat. No. 7,290,967; issued on Nov. 6, 2007; Inventor, Steimel; Johannes (Neidlingen, Del.). While presumably effective in its general dust extraction purpose this device is an accessory which must be connected to the base of the router and removed as needed. It is designed to be hooked up to a vacuum making it a rather cumbersome attachment. Another prior art example U.S. Pat. No. 7,198,442 B2; issued on Apr. 3, 2007; Inventor, Mike Waldron (Pocklington, GB) similarly focuses on dust extraction via vacuum. To encourage dust extraction Waldron and Steimel both disclose a removable guard portion positioned partially around the router bit and below the bottom work contacting surface of the router. As such during many routing operations this lower guard portion becomes an obstruction which must be removed from the router creating non-productive downtime. When removed the guard portion may become misplaced, lost or forgotten when the router is taken from one job site to another. Reattachment creates additional downtime which at times results in the device not being replaced and therefore not being used at all. Both dust extraction devices are relatively complex and expensive to manufacture and purchase and both create additional weight related operator fatigue. While both Steimel and Waldron both present useful devices which naturally provide some guarding and chip deflection as a by-product of their design, they do not provide a simple or practical always on-board solution for chip deflection, they are designed for dust extraction via vacuum.
Another prior art example U.S. Pat. No. 6,027,289; issued on Feb. 22, 2000; Inventor, Posh; Ransom (Livonia, Mich.) shows an optional chip deflector(s) arrangement which is designed to deflect debris as it exits the openings in the router base. The hinged deflector(s) are located above the work contacting surface of the router therefore they do not provide protection from debris exiting from below the work contacting surface of the router. Other clear plastic devices which cover the openings in the router base and deflect some exiting debris are well known, such devices are also located above the work contacting surface and do not provide protection from debris exiting from below the bottom work contacting surface of the router. Because that is where all the actual cutting occurs most of the debris is expelled from this area.
In another prior art example U.S. Pat. No. 4,484,845; issued on Nov. 27, 1984; Inventor, Pennella, Jr. et. al. shows a “Machine Tool Safety Shield” with removable and repositionable guard members attached to an anchor panel which is universally mountable to machine tools. Machine tools are equipment that cut, shear, punch, press, drill, roll, grind, sand, or form metal, plastic, or wood stock. Not included in this definition are hand-held, portable power, or manual tools.
The objective of the multiple guards is to permit the device to essentially surround the tooling and present a barrier between the cutting tool and the operator. While practical for machine tool applications the Pennella device as well as similar prior art machine tool guards would be impractical, obstructive and counterproductive for use with routers, adding needless cost, weight, and bulk to a hand held power tool.
USPTO Backgrounds
USPTO Backgrounds