Jodee from Inspire Woodcraft demonstrated the test featured in this video.
The video revisits the familiar “saw blade drill bit trick”—using a drill bit the same diameter as a blade is thick to offset blade thickness for certain table saw joinery—and asks whether the shank and cutting end of a drill bit actually measure the same.
Jodee measures several twist and brad-point bits with calipers, compares older worn bits to new sets, and reports on what those measurements mean for woodworkers.
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The Question: Do Drill Bit Ends Match?
Many viewers suggested that the shank diameter of a drill bit could differ from the fluted or cutting end, which would undermine tests that measure only one end.
The test aims to determine whether those perceived differences are real, or just the result of worn bits or measurement error.
How the Test Was Performed
Jodee measured both ends of two types of bits commonly used in woodworking: twist bits and brad-point bits, starting with some older bits from the shop and then purchasing brand new sets for comparison.
Measurements were taken with calipers, and results from older tools were compared against readings from a new, more accurate set of digital calipers.
What the Results Show
The measurements showed that, for the bits tested, the shank and the business end measure the same or close enough for practical purposes.
This aligns with how bits are manufactured: they begin as a round blank, and milling creates the flutes and cutting geometry without adding material to the outside diameter, so the outside diameter should remain consistent along the length.
Small exceptions include intentional step reductions for chuck jaws, add-ons, or wear from years of use, which can create measurable differences in some shop bits. Caliper accuracy also matters—different tools can give slightly different readings, so verification with a reliable instrument is useful.
Implications for the Saw Blade Drill Bit Trick
If a drill bit and blade thickness are being matched for joinery offset, using a bit that measures the same at both ends generally makes the trick legitimate for the common bit types tested. For bits under a quarter inch and typical woodworking twist or brad-point bits, the outer diameter consistency supports the technique.
However, woodworkers should be cautious with unusually manufactured bits, worn bits, or those with stepped shanks; those variations can affect fit and accuracy. When precision matters, verify with good calipers and test-fit before committing to a setup.
Tips for Accurate Measurement and Best Practices
Use quality digital calipers and measure multiple points along the bit to confirm consistency rather than relying on a single reading. Checking new bits versus well-used ones helps identify whether differences come from wear or from manufacturing features like step reductions.
When applying the drill-bit offset trick, choose bits appropriate for woodworking and keep expectations realistic; a close match is usually sufficient for jigs and joinery, but fine cabinetry or critical fences may require additional checks and tweaks.
Conclusion
The test settles a common shop debate by showing that, for typical woodworking bits, the shank and cutting end generally measure the same and the saw blade drill bit trick remains a practical option when done carefully.
Confirming measurements with good calipers and accounting for wear or special shank features makes the technique reliable in most shop situations.
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