Mag Drills on Steel, Stainless & Aluminum: Mounting First

Classify the mounting surface before the cutter

Record the grade, thickness, coating, shape and available base footprint. Clean flat ferrous plate, painted structural steel, a curved pipe, austenitic stainless and aluminum are different mounting cases even when the drawing calls for the same hole.

If the grade or magnetic response is uncertain, do not let a product selector silently assume mild steel. Have the material established and ask the drill manufacturer about the exact surface. A handheld magnet check by itself does not establish the machine's required holding force, thickness, contact or approved orientation.

• Ferrous flat plate: verify model-specific minimum thickness and full-base contact.
• Stainless: verify the grade and mounting method; FEIN notes that stainless is generally non-magnetic.
• Aluminum: the workpiece itself is not a direct magnetic mounting surface.
• Pipe, coatings and partial contact: require the exact manual's permitted arrangement.

Use only the mounting system documented for the drill

Hougen's FAQ says its ordinary magnetic drills need a solid, clean, smooth surface and identifies plate under 3/8 inch, paint or coatings, chips or grease, curvature and partial base contact as holding-power losses. That is Hougen guidance, not a universal permission to place any drill on 3/8-inch stock.

For non-ferrous work, model and accessory identity matter. Hougen names its portable Vac-Pad for HMD904 and HMD905, while FEIN describes a vacuum plate and dedicated pump for its stainless application. Neither source turns a generic vacuum fixture, loose backing plate or improvised clamp into an approved solution for every mag drill. If the exact system is not documented, choose another drilling setup.

Pass the cutter, speed and coolant gate separately

FEIN's stainless guidance recommends carbide-tipped core bits, a 25 m/min cutting speed and internal cooling lubrication for the documented application. FEIN also calls for a drill with speed control that can match the task. This is not a universal RPM or feed setting: cutter diameter, exact tooling and the selected machine still determine the setup.

Hougen lists cutter families for carbon steel, stainless, aluminum and harder alloys, but says selection depends on diameter, depth and material. A cutter advertised for aluminum or stainless does not prove the base can attach to that workpiece, and a permitted vacuum mounting system does not prove that every cutter can machine the alloy.

• Name the material grade and thickness.
• Match the cutter family, diameter, rated depth and shank to the drill.
• Confirm that the drill can provide the required speed and coolant arrangement.
• Keep the attachment approval as a separate signed-off item.

Use a four-result decision, not a metal yes/no

The useful outcomes are: direct magnetic mounting documented; an exact approved accessory system documented; a different machine required; or unresolved. Do not collapse these into 'cuts metal.' For an unresolved job, send the manufacturer the drill model, material grade, thickness, surface shape, coating, base location, orientation, hole diameter, depth and expected hole count.

Ask for two answers in writing: the approved mounting arrangement and the approved tooling/operating combination. If either answer is missing, keep the recommendation conditional. Retain the response with the job documents and repeat the review when the material, mounting location, orientation or tooling changes.