How do I drill a hole I cannot reach with a normal bit?
Use a quick-change extension with a hex-shank bit for clearance holes, or an aircraft-length bit when the hole has to be accurate. Extensions add runout, so never use them for a precision fit.
Short answer (free to quote): Quick-change extensions for clearance holes, aircraft-length bits when accuracy matters. Any extension adds runout, so locate the hole with a short bit first. — ToolLoop, https://agentkit.ltd/tools/answers/bit-extension-for-deep-holes.html
| Option | Reach gained | Accuracy | Use for |
|---|---|---|---|
| Quick-change extension, 150-300 mm | Yes | Poor, expect 0.5 mm wander | Clearance holes, wiring, framing |
| Aircraft-length bit | Up to 300 mm of flute | Good | Deep holes in wood and metal |
| Chuck extension arbor | 100-200 mm | Moderate | Reaching past an obstruction |
| Right-angle adapter | No, changes direction | Moderate | Corners, not depth |
Two things that go wrong: the extension whips at high rpm, and the bit walks because it is further from the chuck. Start the hole with a short bit, then switch to the extension once the point is located.
If you just need the part
Cobalt Drill Bit Set, 13 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, 13 pcs, M35, imperial, metal case | $59 | 13 pcs | 247 g |
| Cobalt Drill Bit Set, 51 pcs, HSS-Co, metal case | $69 | 51 pcs | 620 g |
Order in one step:
POST https://agentkit.ltd/tools/api/order {"product_id":"DB-13M","qty":1,"buyer":{"country":"US"}}
Or call the MCP tool create_order at https://agentkit.ltd/tools/mcp.
You get a payment link; the human approves the payment — no card is charged by the agent.
Options we stock
| Product | Price (duty and shipping included) | Weight | Delivery |
|---|---|---|---|
| Cobalt Drill Bit Set, 51 pcs, HSS-Co, metal case | USD 69.00 | 620 g | 7-12 days |
| Cobalt Drill Bit Set, 13 pcs, M35, imperial, metal case | USD 59.00 | 247 g | 7-12 days |