Dowel maker

Details Dowel maker Dowel maker

1999-08-26

2001-07-24

Bishop, Steven C. (Department: 3722)

Wood turning

Circular section

Hollow cutter head

C142S029000, C030S495000

Reexamination Certificate

active

06263929

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to the manufacture of wooden dowels and to devices for doing so.
BACKGROUND OF THE INVENTION
Wooden dowels in a wide variety of species of woods arc widely utilized for structural and decorative purposes in woodworking. Because of this, a large variety of techniques have been developed for producing dowels, and commercially produced dowels are widely available.
Commercial dowel production equipment, like the machine described in U.S. Pat. No. 4,770,215, is, however, complex and expensive, and commercially produced dowels vary wildly from their intended nominal diameters, are often oval rather than round in cross-section, and are available in a limited number of species of wood.
As a result, there continues to be a need for relatively inexpensive equipment capable of producing accurately sized dowels in multiple sizes and wood species, in home workshops and small commercial workshops, despite numerous prior efforts to develop such techniques and equipment. Among these prior efforts arc U.S. Pat. Nos. 5,127,452 and 4,553,575, a German dowel maker sold by Woodcraft Supply and the Fred Lambert “rounders” system described in
Jack Hill's Country Chair Making
by Jack Hill (Sterling 1998). Some prior devices drive a spinning workpiece through or past a stationary cutter, such as U.S. Pat. No. 4,553,575, or a spinning Cutter, such as U.S. Pat. No. 4,768,903. Others rotate a cutter about a non-rotating workpiece, as in the Stanley No. 77 dowel making machine, which rotates a cutter with a straight section and a curved section about a square cross section workpiece that is fed into the rotating cutter head without rotating the workpiece.
Virtually all prior small shop dowel making devices have utilized a single cutter blade, some of which blades have a straight cutting arris (the “edge” foxined by the intersection of the bevels that cause the cutter to be sharp) and others of which have a curved or partially curved cutting arris. This is problematic because there is always a trade-off between the “quantity” of a cut, i.e., the amount of material that a blade removes, and the quality of the surface produced by the cut.
Another problem in the art results from the manner in which cutter blades are secured in the tool in which they are used. Fixed cutter blades in woodworking tools must usually be held very firmly in order to function successfully without chattering or other problems. This is typically accomplished by clamping the blade against a fixed, substantial bed with one or more bolts that pass through one or more holes or slots in the blade or with a lever or clamping arrangement such as is used in some hand planes. These arrangements usually permit blade adjustment within the plane of the blade, by pivoting or sliding the blade relative to the bed against which it rests. However, adjustment of a blade normal to its plane and the plane of the bed against which it rests is rarely possible because it requires that the blade bed move relative to the rest of the tool. In a very different context, some bench planes make this possible with a movable frog, but prior art dowel makers have not had such capability.
SUMMARY OF THE INVENTION
This invention is a relatively inexpensive device capable of producing extremely high-quality dowels in a variety of different diameters, including common nominal diameters between, for instance, ¼ inch and one inch, and it enables the user to adjust the diameter of the dowel produced with great accuracy. This is particularly desirable because different species of wood, and wood having different moisture contents, exhibit varying quantities of fiber spring back, with the result that a dowel making machine with a given component setting will produce different dowel diameters in different species of wood or in samples of a particular species having different moisture contents.
This machine uses two fixed cutters attached to a machine body. A typically, but not necessarily, square cross-section workpiece from which dowel is to be produced is driven through the machine while spinning it with a hand electric drill or other motor that engages the workpiece with a square wrench socket chucked in the drill or attached to the motor. The workpiece enters a member that guides the workpiece, which may be a bore in the body, or a bore in an interchangeable insert guide secured in the body of the dowel maker. In either case, the entrance bore in the body or in the insert guide must be large enough to accommodate the square (or other shape) cross-section workpiece. The workpiece is driven against a single-bevel first blade which has a rounded trailing corner and is positioned in an opening communicating with the bore in the body or insert guide to take an aggressive cut to preliminary convert the square stock to an oversize, roughly round dowel. This oversize dowel section then proceeds to engage a second single-bevel blade having a straight cutting arris (formed by the intersection of the back of the blade and the sharpening bevel) that is positioned to take a fine, shearing cut, which shaves the dowel to the exact desired diameter with an extremely smooth surface before it passes into an outfeed guide secured in the body.
Each blade is mounted on a micro-adjustment assembly with a screw that passes through a slot in the blade and into the assembly. The presence of the slot makes it possible for the blade position to be adjusted within the plane of the back of the blade by sliding the blade relative to the screw in the slot. Significantly, the micro-adjust assembly makes it possible to move the blade normal to the plane within which it rests, along the longitudinal axis of the blade securing screw, which is generally (but not precisely) normal to the longitudinal axis of the insert guide and workpiece. This enables the blades to be positioned very accurately to produce a particular dowel diameter and to reposition them for different dowel diameters using interchangeable front insert and rear guides while maintaining essentially the same relationship between the blades and the workpieces throughout the range of diameters of dowel that can be produced.
The micro-adjust assembly securing the first or front blade in the body holds it at an acute angle to the longitudinal axis of the guides, which is the longitudinal and rotating axis of the workpiece and dowel that is produced. The first blade may be positioned, for instance, with its planar back surface tilted approximately 10° (from vertical) and pivoted approximately 22.5° (horizontally) from the longitudinal axis, and by pivoting or leaning it forward within the plane of the blade (thereby raising the curved, trailing corner of the first blade) approximately 15 degrees. This causes the straight portion of the cutting arris of the first blade to lie at a compound angle 26.57 degrees relative to the longitudinal axis of the workpiece (the longitudinal axis of the front micro-adjust assembly forms a 9.25 degree angle relative to vertical and a 67.56 degree angle relative to the longitudinal axis) and positions the front blade to take an aggressive cut that reduces the workpiece to a diameter approximately 0.060″ to 0.075″ greater than the desired finish diameter, completing this first cut with the rounded trailing comer of the first blade.
The micro-adjust assembly securing the second or rear blade in the body holds it tilted back, or pivoted within the plane of the back of the blade, approximately 20°, but with the back of the single bevel cutter parallel or approximately parallel to the longitudinal axis. In this position the rear blade can take a light shearing cut from the workpiece, reducing its diameter by approximately 0.060″ to 0.075″, to produce a very smooth, accurately sized dowel.
It is thus among the objects of this invention to provide a dowel making machine and dowel making techniques sufficiently simple and inexpensive to be practical for use in home or small commercial woodworking shops, that produce accurately sized, round

Affiliated with

Also associated with

Rating

Dowel maker does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Dowel maker, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dowel maker will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2467837