DEWALT DWE4120: problems, parts and running costs
Checked: 2026-10-17
Summary
The DEWALT DWE4120 is a compact 3.9 lb corded 4-1/2 in angle grinder with a 9 amp motor spinning at 12,000 RPM. No recurring failure pattern is documented; the expected maintenance is brush replacement on the brushed motor, and the main care point is that parts are type-specific across Type 1, Type 2 and Type 15. Prices at other retailers in October 2026 ran from $107.99 to $155.30, and the tool is a solid buy at or below $110.
Common problems and fixes
- Brush wear — the 9 amp motor is brushed and will need brush replacement over time; brushes are a serviceable part, and pop-off brushes are designed to protect the armature at end of life. [6][19]
- Type-specific parts — the DWE4120 has been produced in Type 1, Type 2 and Type 15 with type-specific components; confirm the tool’s type number before ordering parts or they will not fit. [11]
- No dust ejection — the DWE4120 has no dust ejection system, unlike the DWE402, so expect more dust in the gear case over time. [4][15]
- No variable speed — there is no electronic speed control, so the 12,000 RPM no-load speed cannot be turned down for softer materials. [7][16]
Parts and consumables
- Brushes — serviceable and replaceable; no part number is published in the sources. [19]
- Armature, field, gearcase assembly, spindle assembly and gear — replaceable components listed for DWE4120 Type 1; confirm your tool’s type before ordering. [19]
- Grinding and cutting wheels — the 5/8"-11 spindle accepts standard 4-1/2 in accessories, so there is no proprietary lock-in; wheels are the routine consumable. [1]
- One-Touch guard and hex wrench — included with the tool. [1][7]
Yearly running cost
Not enough data. The sources list grinding/cutting wheels, replacement brushes and electricity as the recurring costs but give no per-year figure.
When it is a good buy
Prices observed at other retailers in October 2026: CPO Power Tools $107.99, Actionis $114.09, ToolOrbit $133.69, Linde Gas & Equipment $155.30 and MSC $125.06.
- At or below $110 — solid value for a compact 9 amp corded grinder; the CPO price of $107.99 lands here.
- $111-130 — fair value; the Actionis price of $114.09 and the MSC price of $125.06 land here.
- $131-160 — weak value unless the lighter 3.9 lb body matters; ToolOrbit’s $133.69 and Linde’s $155.30 land here.
- Above $160 — poor value for this model.
Named alternatives:
- DEWALT DWE4120W (kit with a grinding wheel) — better if you want a wheel in the box.
- DEWALT DWE4120N (no-lock-on variant) — better where a lock-on paddle is unwanted.