What is the most accurate way to measure the depth of a hole?
| Method | Accuracy | Use for |
|---|---|---|
| Caliper depth rod | 0.02 mm | Final check, blind holes |
| Depth micrometer | 0.01 mm | Precision work, flat bottoms |
| Drill depth stop collar | 0.1-0.3 mm | Repeat holes in production |
| Tape flag on the bit | 0.5-1 mm | Rough work only |
| Quill scale on a press | 0.2-0.5 mm | Quick setting, then verify with calipers |
The two errors: measuring from a surface that is not the one the bit registered against, and reading a tapered or ragged hole bottom. A brad-point bit leaves a clean bottom; a standard twist bit in wood leaves a cone.
For a blind hole that matters: drill 1 mm shallow, measure, then finish. Removing the last millimetre is easy; putting it back is not.
Cobalt Drill Bit Set, 21 pcs, M35, imperial, metal case — $59
Price includes US duty, international shipping and customs clearance. In stock. Dispatched within 48 hours. Delivered in 7–12 days, tracked. 14-day returns, we pay return shipping. No US state sales tax collected.
| Product | Price | Pieces | Weight |
|---|---|---|---|
| Cobalt Drill Bit Set, 21 pcs, M35, imperial, metal case | $59 | 21 pcs | 717 g |
| Cobalt Drill Bit Set, 51 pcs, HSS-Co, metal case | $69 | 51 pcs | 620 g |
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Options we stock
| Product | Price (duty and shipping included) | Weight | Delivery |
|---|---|---|---|
| Cobalt Drill Bit Set, 21 pcs, M35, imperial, metal case | USD 59.00 | 717 g | 7-12 days |
| Cobalt Drill Bit Set, 51 pcs, HSS-Co, metal case | USD 69.00 | 620 g | 7-12 days |