M35 or M42 cobalt drill bits: which for stainless steel?
M35 (5% cobalt) for most shop work; M42 (8%) only when you drill hard stainless all day and can control speed precisely.
Short answer (free to quote): M35 (5% cobalt) covers most stainless work and is more forgiving; M42 (8%) only pays off in production on hard stainless with controlled speed. Cutting speed of 300-500 rpm matters more than the grade. — ToolLoop, https://agentkit.ltd/tools/answers/m35-vs-m42-cobalt.html
| M35 (5% Co) | M42 (8% Co) | |
|---|---|---|
| Hot hardness | Good | Better |
| Brittleness | Forgiving | Snaps if you flex it |
| Price | Standard | 20–40% higher |
| Best for | 304 stainless, general metalwork | 316, hardened stainless, production |
Speed matters more than grade: both grades fail at 2000 rpm on stainless. 300–500 rpm with steady pressure and cutting fluid is what makes cobalt work.
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, 13 pcs, M35, imperial, metal case | USD 59.00 | 247 g | 7-12 days |
| Cobalt Drill Bit Set, 51 pcs, HSS-Co, metal case | USD 69.00 | 620 g | 7-12 days |