Mag Drill Making Rough or Oversize Holes

Define the defect in measurable terms

Record the required diameter and tolerance from the job specification, then record how the finished hole was measured. Note the measuring tool and whether the measurement was taken near the entry, middle or exit. Avoid accepting or rejecting a precision hole from appearance alone.

Photograph the entry and exit separately. A visible burr, an out-of-round opening and a misplaced hole should be described separately even if they occurred in the same operation. For safety-critical fabrication, the responsible inspector or engineer should decide whether a part can be accepted or repaired.

Build a record that isolates variables

Identify the drill, arbor, cutter and pilot pin by their actual markings. Note the workpiece material, thickness, number of layers and support arrangement. Write down what changed since the last acceptable hole: tooling, mounting location, operator setup or material batch.

Use the manufacturer manual to establish which user inspections are permitted before attempting adjustments. Do not tighten random slide screws until the machine feels stiff. Likewise, an arbor that appears loose needs an appropriate inspection, not an improvised shim.

• Keep an acceptable sample for comparison if one exists.
• Record whether the issue affects every hole or a particular location.
• Separate measured diameter from positional error on the drawing.

Confirm the next action before cutting again

The Milwaukee 2787/2788 operator manual directs users to maintain the tool and obtain appropriate service; its instructions apply to those models. A service diagram can identify parts, but it does not by itself certify that an owner can diagnose runout or rebuild a spindle.

Ask the machine or cutter manufacturer which checks distinguish a tooling issue from a machine alignment issue. If a replacement cutter is recommended, retain the old one for comparison. Resume production only after the setup and inspection method are acceptable for the job, rather than assuming a cleaner-looking hole must meet tolerance.