troubleshooting
Mag Drill Magnet Not Holding: Surface, Load or Fault?
If a mag drill shifts or lifts, stop the motor, secure the machine independently and do not attempt another hole. Diagnose three branches in order: whether the workpiece can support the exact magnetic base, whether the cutter/load is pushing an otherwise eligible setup, and whether the machine has a fault. A safety chain controls a fall; it does not restore holding force.
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Branch 1: prove the mounting surface
Record the exact drill, base version, measured thickness beneath the whole magnet, material grade, coating, curvature, nearby edges and orientation. Hougen identifies stock under 3/8 inch, coatings, chips or grease, curved surfaces and partial base contact as reduced-hold conditions. The US S28MAG page separately lists a 3/8-inch minimum plate thickness.
Clean only as the manual permits and photograph the stationary full footprint after the machine is safe. Do not grind the base, bridge a gap with loose scrap or bypass a sensor. If the workpiece is non-ferrous, below the model limit, partially supported or otherwise outside the manual, stop this branch and use an exact approved system or another machine.
Branch 2: separate initial grip from cutting load
A base that grips before drilling but lifts as the cutter enters has not passed simply because the magnet switched on. Hougen says drill or workpiece movement can break a cutter and identifies a dull cutter as one cause that can push a magnet off the surface. Stop and inspect the exact cutter, pilot, chips, coolant path and documented feed procedure rather than adding handle force.
The Milwaukee 2787/2788 manual makes the load distinction explicit for that permanent-magnet platform: excessive feed can break the magnet free, while enough pressure to form a curled chip is the operating cue. Do not transfer its 1/4-inch ferrous-stock minimum to another drill, but do use the example to separate a surface that never held from a setup that releases only under cutter load.
Holding-force headlines cannot diagnose the job. Hougen's standard HMD904 figure changes from 1,750 pounds dead lift on 1-inch plate to 1,310 pounds on 3/8-inch plate, and the swivel-base figures differ again. Those values show why base version and test plate matter; they are not an on-site force reading or permission to continue.
- Identify the complete model and voltage from the machine label.
- Record whether failure occurred before contact, during entry or deeper in the cut.
- Record cutter part, diameter, rated depth, condition and material.
- Check whether the manual permits the surface shape and drilling orientation.
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Check AmazonBranch 3: isolate a possible machine fault
First separate an interlock from weak holding. On Milwaukee 2787/2788, the motor will not start until the permanent-magnet knob icons align. A machine that remains attached but will not start belongs in the startup diagnostic branch; extra feed force cannot fix an unconfirmed magnet setting.
Visible base damage, a damaged cord or switch, repeated loss of attachment on a verified eligible surface, or an uncertain lift-protection device calls for manufacturer service. Do not open the magnet, bypass protection or continue test cuts to reproduce the failure.
Send support the exact machine and base version, photos of the safe stationary setup, material and thickness, surface condition, orientation, cutter details and the point in the cycle where movement began. Ask separately whether the setup is approved and whether the machine needs inspection. Keep it out of service until both questions are resolved.
Questions, answered
Does a safety chain fix a weak magnet?
No. Hougen requires a chain or strap as secondary restraint, especially horizontally or overhead, but it does not make thin, dirty, curved, partial or non-magnetic contact acceptable.
Should I replace the drill immediately?
Not from the symptom alone. First establish whether the job meets the exact model's mounting limits and whether cutter load caused movement. Visible damage or repeated failure on a verified eligible setup needs manufacturer service.
