Wood turning process and apparatus for making cylindroconical wood products
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The process of this invention is associated with the field of wood-turning technology, specifically as related to the manufacture of wood products comprised in part of cylindroconical rings turned from plywood. More specifically, the procedure of this invention provides an expeditious means for manufacturing strong cylindroconical rings from plywood in a manner which minimizes waste of material. 
     2. Description of the Prior Art 
     Techniques commonly used for manufacturing cylindrical wood receptacles and other products include use of stave-type construction and the use of lathes to turn such products from wood logs. The use of stave-type construction limits the shape of the product to maximum curvatures obtainable by bending and shaping staves. Construction from wood logs or blocks requires extensive lathe time and causes excessive waste of materials. 
     The use of stacked rings of varying diameters is an alternative to use of stave-type or lathe-type construction described above. However, heretofor such rings were usually cut from wood sheets by using a band saw, saber saw or hole cutter. The use of a band saw or saber saw requires a wide and uneven saw cut which must be started by drilling or cutting material adjacent to the ring being manufactured, thus spoiling said adjacent material for later use. The use of a hole cutter limits manufacture to non-conical rings only. 
     Therefore, it is an object of this invention to achieve an economical and effective wood-turning process for use in manufacturing strong, concentric, cylindroconical rings which may stacked and glued to form wood products having a wide variety of annular configurations. 
     SUMMARY OF THE INVENTION 
     In achieving the object of an economical wood-turning process for making annular wood products from a sheet of wood material such as plywood, a cutting tool is used to cut a generally round piece of said wood material into a plurality of concentric, cylindroconical, annular rings. The conical angle and the thickness of said rings are chosen such that said rings may be stacked and adhered to one another to form a hollow wood product of cylindroconical shape. Additional pieces of plywood may be cut and assembled in similar manner to combine with the previously cut rings to form a wood product with a multiplicity of cylindroconical angles. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view showing critical dimensions for cutting conically-shaped rings and showing stacking of the rings. 
     FIG. 2 is a side view of a wood-turning machine used in the process of this invention. 
     FIG. 3 is a top view of a wood-turning machine used in the process of this invention. 
     FIG. 4A is a cross-sectional view of wood receptacles of the type which may be manufactured using the process of this invention. 
     FIG. 4B is an alternate cross-sectional view of wood receptacles of the type which may be manufactured using the process of this invention. 
     FIG. 4C is still another alternate cross-sectional view of wood receptacles of the type which may be manufactured using the process of this invention. 
     FIG. 5 is a side view of a cutting blade used in the process of this invention. 
     FIG. 6 is an end view of the cutting blade used in the process of this invention. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 depicts a cross-sectional view of a diameter of a generally round piece of processed lumber or similar wood material 1, preferably marine plywood of three-fourths inch thickness. The procedure of this invention generally requires that lower outer radius R1 of cylindroconical ring 2 be substantially equal to upper outer radius R2 of adjacent cylindroconical ring 3. For a given thickness of material 1 and given width of cutting blade, the conical angle and ring thickness are adjusted to result in proper radial distances. For example, I have found that, by using three-quarter inch plywood and a blade thickness of approximately one-twentieth inch, a conical angle in the range of 25° results in ring thickness of one-fourth to five-sixteenths inch. 
     It is possible, using the process of this invention, to manufacture up to 72 8-inch-diameter, 5-inch-heighth products from one 4-foot by 8-foot sheet of 3/4 inch plywood. The resulting products have great strength, form and beauty. 
     The processed lumber or other similar material 1 may be cut into generally round discs of wood material 1 through use of a saber saw or other cutting instrument. Use of a generally round disc rather than a generally square piece of material 1 for starting the process is recommended for the purpose of safety and reduced machine size, as will be apparent from further discussion of the procedure of this invention. 
     FIGS. 2 and 3 depict a wood-turning machine for use with the process of this invention. The Figures indicate a 8-inch-diameter piece of processed lumber material 1 mounted on a rotatable shaft 4. The 8-inch-diameter disc is turned at from 800 to 1000 revolutions per minute by a drive means which may be comprised of pulleys 5, belt 6 and motor 7. I have found that, in order to prevent excessive heat from being generated during cutting operation, the maximum circumferential speed of the disc should be less than 26,000 inches per minute. Rotatable shaft 4 and said drive means are mounted on frame means 8. 
     Two cutting bits, 9 and 10, are directed toward each other and positioned such that the tooth ends of said bits are displaced from each other a distance greater than one and one-half times the thickness of wood-material 1. Said cutting bits are mounted in a bit-holding-guide means 11 which may be comprised of a generally U-shaped block with said bits directed toward each other from the inner sides of said U-shaped block. 
     Bit-holding-guide means 11 is slidably mounted on swivel means 12. Swivel means 12 is rotatably mounted on a table guide means 13. Table guide means 13 is slidably mounted on frame means 8. 
     The process of the invention requires setting the cylindroconical angle of the ring or rings to be cut by rotating swivel means 12 to adjust the angle between bits 9 and 10 and wood material 1. Once the angle is set, first locking means 14 is activated to prevent further rotation of swivel means 12 with respect to table guide means 13. The cylindroconical angle is always chosen to have pointed and away from shaft 4. 
     Table guide means is then slidably adjusted along a path such that bits 9 and 10 move parallel to a radius of wood material 1 until positioned to cut the largest diameter cut to be made on wood material 1. Second locking means 15 is activated to prevent movement of table guide means 13 with respect to frame means 8. 
     Shaft 4 is caused to rotate by activating said drive means. Bit-moving means 16, which may constitute a worm gear or threaded screw mechanism, is activated to cause bit-holding guide means 11 to move non-shaft-side bit 10 in the direction of point of said bit until said bit has cut a channel to a depth approximately equal to one-half the thickness of wood material 1. 
     Bit-moving-means 16 is then disengaged from either bit-holding-guide means 11 or swivel means 12 by activating release means 17. Bit-holding-guide-means 11 is quickly moved to it starting position with bits 9 and 10 out of contact with wood material 1. Prolonged contact between the bit and rotating wood material causes overheating of the bit. 
     Release means 17 is then re-connected to either bit-holding-guide means 11 or swivel means 12, preferably at a new location chosen to eliminate the need to return bit-moving means 16 to its original position. 
     Bit-moving-means 16 is then activated to cause shaft side bit 9 to move in the direction of point of said bit until said bit has cut a channel through wood material 1 to a depth sufficient to connect with the channel previously cut. 
     Release means 17 is then activated and bit-holding-guide means 11 is returned to a position such that bits 9 and 10 are not in contact with wood material 1. Rotation of wood material 1 may be ceased and the cut material removed from the apparatus. 
     Assuming that the outer cylindroconical angle of the next ring is the same as that of the first, second locking means 15 is de-activated and table guide means 13 is moved to a second location, which is usually chosen such that the next ring will stack with the first ring to form a continuous cylindroconical angle. I use for my second locking means 15 a variety of removable templates attached to frame means 8. Each template has a series of locking notches spaced to correspond to the proper ring width for a given angle of cylindroconical cut. Table guide means 13 is provided with a simple protruding member which is placed in each locking notch as subsequent smaller diameter rings are cut. 
     The cutting process described above is repeated until the desired number of cylindroconical rings have been cut from wood material 1. It is, of course, unnecessary to cause the rotatable shaft 4 to cease rotation between the cutting of rings. For construction of spherical and similar-type wood products, it is necessary to change the cylindroconical angle between the cutting of each ring. 
     The central part of wood material 1 may be used as the top or bottom surface of the wood product constructed by stacking cylindroconical rings. Construction of the wood product is accomplished by use of glue or other adhering substance to attach the stacked rings to form the desired shaped product. For added strength and beauty, I attached the wood product to the end of the rotatable shaft 4 and applied clear resin coating to the inside of the rotating material. The result is a strengthened container with translucent areas in the region of cross-cut wood fibers. 
     It is obvious that a wide variety of the wood products may be made using cylindroconical rings cut with a variety of cylindroconical angles from a multiple number of discs of wood material 1. Examples are indicated in FIGS. 4A, 4B, and 4C. 
     Bits 9 and 10 are preferably formed as indicated in FIGS. 5 and 6. FIG. 5 indicates a side view of one of the bits showing a pointed tip 18. Tip 18 is shaped with beveled edges 19 as shown in FIG. 20. The particular shape results in a cut of minumum width and in operation with no binding between blade and material. 
     It is understood that the process described above is susceptible to various modifications, changes, and adaptions without departing from the scope of the invention as set forth in the appended claims.