CRAFTSMAN V20 BRUSHLESS RP 4.5-Inch Circular Saw (CMCS405B): problems, parts and running costs

Checked: 2026-10-17

Summary

Owner evidence for this exact model is thin: Lowe’s shows zero customer reviews and no established test outlet has measured it, but one Reddit thread on the larger sibling saw reports lockups and weak running on batteries. Keeping it running costs whatever you pay for a V20 battery and charger plus blades you wear through; the saw carries a 3-year limited warranty. [1][2][4][5]

Common problems and fixes

No battery or charger in the box — the saw is sold as a bare tool and cannot run until a V20 battery and charger are bought separately. Fix: factor a battery and charger into the total, or buy only if you already own V20 batteries. [1][2]
Locking up and weak running on the sibling saw — a Reddit thread on the larger V20 7-1/4-inch brushless circular saw reports one owner saying it “kept locking up” on both a 4Ah and a 9Ah battery and calling it “super weak”. This is not direct evidence about the 4.5-inch CMCS405B, but treat it as a platform-level caution about the V20 brushless line. [5]
Bevel and speed trail the bigger saws — 4,500 RPM and a 45-degree bevel sit below the brushless CMCS551 (5,000 RPM, 56 degrees) and the corded CMES510 (5,500 RPM), so repeated full-depth rips are slower. Fix: use this saw for trim, panels and sheet goods in tight spaces; pick a 7-1/4-inch saw for ripping. [6][7]

Parts and consumables

Sliding rip fence and auxiliary handle — included in the box; no other accessories ship with the saw. [2]
No parts catalog or replacement-parts documentation has been published for this model. [2]

Yearly running cost

Not enough data.

When it is a good buy

Acme Tools listed the bare tool at $119.00, marked down from $179.00, during a price-drop event; Lowe’s carries it at location-dependent pricing. [3][4] Pro Tool Reviews noted a $129 bare-tool price for the larger CMCS551, which positions the CMCS405B as the lower-priced compact option in the brushless line. If you are new to the platform, a compact saw kit with the battery included from another brand can undercut the total. [6] Alternatives: the larger CMCS551 7-1/4-inch brushless saw is the better choice when cutting capacity matters more than size; the corded CMES510 is the choice when you want to avoid battery platform costs entirely. [6][7]