| 1 | Choose a metal-cutting saw | Use a bi-metal hole saw for general work in sheet steel, mild steel, and many stainless-steel applications. For frequent cutting or tougher materials, select a carbide-tipped saw rated by its manufacturer for that metal. | Check the saw’s material rating and maximum speed. Use a sharp saw; worn teeth generate excess heat and can wander. |
| 2 | Match speed to diameter | Larger saws need lower RPM. As conservative starting points for bi-metal saws: a 1-inch saw may run at about 200–400 RPM in mild steel and 100–250 RPM in stainless steel; a 2-inch saw at about 100–200 RPM in mild steel and 50–125 RPM in stainless steel. | These are approximate starting ranges, not universal limits. Follow the hole-saw and drill manufacturers’ speed guidance, and reduce speed if the cut squeals, smokes, or overheats. |
| 3 | Adjust for aluminum | Aluminum generally permits higher cutting speeds than steel, but the correct RPM still depends on saw diameter, tooth design, and material thickness. Begin below the tool maker’s recommended maximum and increase only if the cut remains controlled. | Use a cutting lubricant suitable for aluminum to help reduce friction and prevent chips from sticking to the teeth. Clear chips regularly. |
| 4 | Use fluid for steel and stainless | For mild steel and stainless steel, use a suitable cutting oil or metalworking fluid. Stainless steel work-hardens if the teeth rub without cutting, so maintain a steady feed and avoid dwelling in the cut. | Apply fluid to the cutting area as directed by the fluid manufacturer. Keep the saw cutting rather than spinning against the work without progress. |
| 5 | Consider the workpiece thickness | Check the saw’s stated cutting depth against the material thickness. For thicker stock, clear chips periodically so they do not pack into the kerf or bind the saw. | For deep cuts, pause with the tool stopped to remove chips and reapply lubricant as needed. Do not force a jammed saw. |
| 6 | Secure the work and control feed | Clamp the workpiece firmly and use a stable drill press or well-controlled drill where appropriate. Start slowly until the teeth establish a groove, then apply even pressure. | Use a pilot drill and arbor suited to the saw. Avoid excessive feed pressure, which can stall the tool, damage teeth, or grab the workpiece. |
| 7 | Treat cast iron differently | Cast iron is commonly cut dry because its graphite content provides some lubricity and liquid can create a messy abrasive slurry. Use a saw specifically suitable for the material and keep the cut clear of dust and chips. | Wear appropriate eye protection and follow workplace guidance for cast-iron dust. Do not use dry cutting as a general rule for steel or aluminum. |
| Speed note: RPM ranges are approximate starting guidance for common metal-cutting hole saws. Actual safe speed varies with saw construction, tooth pitch, material, and machine. Always follow the tool manufacturer’s instructions, secure the work, and wear suitable eye protection. |