• Cobalt drill bits (M35, M42 types) – These hold hardness better under heat and are preferred for stainless.
• High-Speed Steel (HSS) bits – Especially TiN-coated or shorter versions, can work for thinner stainless jobs.
• Point angle, web thickness & geometry – A drill with a 118–135° split-point helps reduce skipping and walking. The web shouldn’t be too thin (it needs strength as you push). For harder stainless grades (like 316), a 135° split-point is preferred. It reduces thrust force and heat, allowing cleaner starts and longer bit life.
• Coatings – Like TiAlN or TiCN, which can prolong bit life by reducing friction and heat buildup.
• Length & flute design – Shorter bits flex less. Good flute geometry helps eject chips and reduce heat.

• Mark and punch – Use a 3-corner pyramid punch or a light scribe. Avoid a conical punch if possible, as it can work-harden the area. A sharp 3-point punch displaces less metal, reducing local hardening. Conical punches create a deeper dimple that can harden the surface, making the bit skate rather than bite.
• Clamp securely – The piece must not shift or spin. Use a backing plate if drilling through-holes.
• Apply coolant / cutting fluid – Lubrication is essential to reduce heat, flush chips and slow down work hardening. Light cutting oils or dedicated metalworking fluids perform best. Avoid WD-40 or general-purpose sprays for stainless — they evaporate too quickly and don’t offer proper lubrication.
• Set up speed & feed – Start slow. Use suggested speeds for stainless steels (lower than for mild steel) and adjust. For austenitic stainless (304, 316 etc.), speeds are modest.
• Start small – For thicker material, start with a pilot or step drill before going to the final size. This reduces cutting load, keeps holes centred and helps maintain coolant access deep into the cut. Aim for a pilot around one-third the final hole diameter.

• Surface speed ~ 20-40 m/min, depending on bit and size. For example, with a 6mm cobalt bit, that’s roughly 1,000–2,000 RPM. For a 10mm bit, reduce to around 600–1,200 RPM. Always err on the slower side and adjust based on chip colour and sound.
• Feed per rev in mm might start around 0.002–0.005 mm/rev, depending on bit diameter 
  
  

Related: How to Drill Through Angle Iron

• Glazing & slipping – Bit is too slow or pressure too low. Increase feed or reduce speed, add coolant. If the bit polishes the surface instead of cutting, resharpen before reattempting — glazed bits won’t bite again properly.
• Bit overheating or breakage – Excessive speed or no cooling. Stop, let cool, sharpen or change bit. Blue discolouration on the bit means it’s lost temper and should be replaced.
• Bit wandering – Insufficient punch mark or feed. Use a centre punch and steady pressure. Double-check your drill is perpendicular to the workpiece.
• Poor chip flow/clogging – Regularly withdraw the bit to clear chips and reapply fluid. If chips jam, they act like an insulator, causing heat and premature wear.