Craftsman CMCF940M1 V20 RP Impact Wrench: problems, parts and running costs

Checked: 2026-10-18

Summary

A 20V brushless 1/2-in impact wrench rated at 700 ft-lbs fastening and 1000 ft-lbs breakaway torque, sold as kit CMCF940M1 with a CMCB204 4.0 Ah battery, a CMCB104 charger and a soft bag under a 3-year limited warranty. The open issues are documentation and evidence gaps: no outlet publishes an instrumented torque measurement, Craftsman and Pro Tool Reviews disagree on the anvil type, and no bolts-per-charge runtime exists. The only recurring cost is battery and charger replacement — sockets are not included — and no yearly total can be computed; under $150 (Farm & Fleet, $139–$149) it is a strong buy, while the $229 retail observed by Pro Tool Reviews is from 2023-06.

Common problems and fixes

No published runtime and no socket-assist mode — Craftsman publishes no bolts-per-charge figure for this model; the 3-speed slide switch (450/1200/2000 RPM) and variable speed trigger are the only speed and torque control, so real runtime is something you measure on your own jobs. [1][3]
Sockets are not included — the kit is the wrench, a 4.0 Ah battery, a charger and a soft bag; you buy your own 1/2-in impact sockets. [1][3]
Instruction manual exists in two revisions — the manufacturer hosts two revisions of the CMCF940 manual with no public changelog explaining the difference. [1]

Parts and consumables

CMCB104 charger — included in the kit. [1][2]
Soft bag — included in the kit. [1][2]
1/2-in impact sockets — not included; owners buy their own, so sockets are a one-time setup expense rather than a consumable. [1][3]

Yearly running cost

No consumables and no subscriptions. The wrench is cordless and no power-consumption figure is published, so electricity cost cannot be estimated. The recurring costs are replacement 4.0 Ah-class V20 packs and chargers; the V20 platform covers 100+ products, which supports pack and charger availability, and the kit ships with only one battery. Sockets are not included but are not a wear item. A yearly total cannot be computed — the sources checked publish no prices or replacement intervals.

When it is a good buy

Street prices in the sources checked: $149 sale / $139 kit brand price at Farm & Fleet (listing undated); $229 retail as observed by Pro Tool Reviews in 2023-06; $199 marked down from $269 at Acme Tools in a price-drop listing whose validity date (2026-09-17) had already passed at the 2026-10-18 check. [5][3][6]

Under $150 it is strong value if genuine: the full 1000 ft-lbs-class rating, a 3-year warranty and a 7.3 lb package with battery.
$150–$199 is fair value: compare it against other cordless impacts and check sale pricing before paying near retail.
$200–$229 is weak value; $229 was Pro Tool Reviews’ 2023 retail, and the “best value” claim then was relative to 2023 competitors.
Above $229 it is poor value unless the compact high-torque package matters and competitors are priced higher.

Named alternatives: the CMCF921B (RP 1/2-in, tool only) at $149, marked down from $199 at Acme Tools, is the better choice if you already own V20 batteries. [6] The CMCF920B brushless mid-torque wrench (275 ft-lbs) suits lighter work. [7] The older brushed CMCF900M1 (350 ft-lbs) kit was listed at $189 by The Drive in 2025-02 — a lower-torque tool, not an upgrade path. [8]