1. Field of the Invention
The invention relates to extension assemblies and, more particularly, relates to adjustable extension assemblies for support surfaces which can be adjusted with respect to the tool on which they are mounted.
2. Discussion of the Related Art
Various bench or table-type machines such as jointers, planers, drill presses, overhead shapers, mortisers, band saws, scroll saws, etc. employ infeed and outfeed surfaces for facilitating the introduction and withdrawal of work pieces to and from the work area and/or support surfaces for supporting the work piece in the work area. It is often necessary to vertically or horizontally adjust the position of such surfaces with respect to the remainder of the machine to adjust the operational parameters of the tool and/or to assure proper operation of the tool. For example, the infeed tables of jointers and planers often are vertically adjustable to increase or decrease the cutting or planing stroke and/or to properly align a support surface with the cutting or planing tool. Similarly, the support tables of drill presses may be adjustable to accommodate varying press strokes.
These infeed and outfeed surfaces and support surfaces often suffer the disadvantage of being insufficiently long to adequately accommodate relatively long work pieces. For instance, the infeed table of the typical jointer is only a few feet long and yet is used to prepare for planing boards which are twelve feet long or even longer. As a result, the operator must manually balance the board on the infeed table while at the same time feeding the board into the machine, thus increasing the chances that the board will not be inserted into or withdrawn from the machine under the proper balancing forces or at the proper angle. This in turn increases the risk that the board will be rapidly jerked into the machine by the cutting blade or that the cutting blade will kick the board away from the machine. In either case, the chances of damage to the board and/or injury to the operator are greatly increased.
To overcome these disadvantages, various devices have been proposed which extend the effective length of the infeed and/or outfeed tables or support surfaces of such machines. However, the typical extension assembly tends to be very complex, is difficult to adjust, decreases the mobility of the machine on which it is mounted, and/or provides insufficient rigidity to support the weight of relatively heavy work pieces. Such devices are also typically employed without providing any additional supports or stabilizers for the machine.
For example, U.S. Pat. No. 4,830,076, which issued to Feyer on May 16, 1989, proposes the connection of an extension table to an adjustable outfeed table of a planer via a large wedge-shaped element which is supported directly on the floor and which is connected to the outfeed table by a complicated fulcrum and pivot rod arrangement. This arrangement is relatively complex and is thus expensive and time consuming to assemble and is also prone to failure. In addition, since both the fulcrum and the wedge-shaped body are supported directly on the floor, movement of the entire assembly is relatively difficult. Finally, no devices are employed to increase the stability or mobility of the machine.
USPTO Backgrounds
USPTO Backgrounds