Box Joint Blade System Single-Pass Cutting
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Solution Overview
Problem
Conventional methods for forming box joints are time-consuming, prone to excessive blade wear, and produce variable groove depths, with existing solutions either being complex and expensive or lacking in cut quality.
Innovation Solution
A system utilizing a rotary saw with left- and right-directed blade members that allow for single-pass cutting of box joints, producing smooth, flat-bottom grooves, and can be easily set up for standard sizes using a single set of blades, with the ability to adjust cut width through blade configuration and optional shims.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a table saw with a standard flat-top blade is used to cut box joints, then the blade can cut through the wood, but multiple passes are required for each finger which is time-consuming and causes excessive blade wear
Solution Approach 1:
The blade is segmented into multiple independently rotating saw teeth arranged in a circular pattern, allowing each tooth to function as a separate cutting element that can remove material in a single pass, eliminating the need for multiple passes required by conventional blades
2Productivity
If a table saw with a stacked dado cutter is used, then repetitive cuts are solved, but the dado cutter must be shimmed to the appropriate cut width and produces scoring at corners
Solution Approach 1:
Each saw tooth is designed with specific local characteristics including positive hook angles optimized for the cutting direction, and the circular arrangement provides different local cutting angles around the perimeter, allowing each portion of the blade to optimize its cutting action for its specific location, producing clean cuts without scoring
3Ease of manufacture
If a router table with a straight bit is used, then box joints can be cut, but the wood is on end with narrow edge against fence which is more susceptible to movements revealing imperfections
Solution Approach 1:
Instead of routing from the end grain with the narrow edge against the fence, the invention uses a table saw configuration where the broad face of the wood is against the fence and the blade cuts from the side, inverting the conventional routing approach and providing greater stability and fewer visible imperfections
4Manufacturing precision
If hand saw and chisel are used to cut box joints, then precise cuts can be made, but it is extremely time-consuming and requires a great deal of skill and practice
Solution Approach 1:
The manual mechanical process of sawing and chiseling is replaced by a powered circular blade system with multiple rotating saw teeth that automatically perform the cutting action, eliminating the need for manual skill while maintaining precision through the engineered blade geometry
Data Source
AI summary
A box-joint blade system includes left- and right-directed blades that each include a saw plate, a set of saw tips, and a set of gullets disposed between the tips. The tips of each blade are axially offset from the saw plate in opposite directions, such that the blades may be mounted on the axis of the saw in either a first configuration, with left and right saw tips outwardly offset and producing a wide cut, or a second configuration, with the tips inwardly offset and producing a narrow cut. In at least the second configuration, the tips of each blade are disposed within the gullets of the other. The tips optionally have a positive hook angle of up to 20° or more, to produce a smooth, flat-bottomed groove in a workpiece.