Replacement Craftsman Mower Blades: 21 and 42 Inch Fits

No. 1 of 6 · Fismiuta

21 Inch Lawn Mower Blade for Walk-Behind Push Mowers

8.4/10 Our score

Best for: Push mowers with circular arbor holes

Pros

• 40MnB boron steel build
• 35% higher impact resistance
• Digital dynamic balancing

Cons

• Incompatible with star spindles

Best for: Walk-behind push mowers with bow-tie spindles

Pros

• 32mm high air lift
• Durable high-carbon steel
• Multi-model walk-behind fit

Cons

• Only fits bow-tie mounts

The 21 Inch Lawn Mower Blade is an aftermarket replacement component specifically manufactured for walk-behind push mowers requiring a bow-tie center mounting spindle. This unit measures 21 inches in length, 2-1/4 inches in width, and 9/64 inches in steel thickness, matching the physical envelope of original walk-behind assemblies. It directly replaces factory part numbers such as Craftsman OEM CMXGZAM100067 along with standard equipment numbers 742-0741, 742-0741A, 742-04100, 742-04276, 742-04276S, 942-0741, 942-0741A, and 942-04276S. The steel is finished with an anti-corrosion barrier designed to protect the metal during storage and shipment, which naturally wears away from the cutting bevel during initial operation.

Engineered around an upgraded 32mm air lift height, this craftsman 21 inch mower blade produces roughly fifty percent stronger aerodynamic draft compared to conventional 28mm stock designs. The reinforced upward draft creates a powerful internal vacuum inside the mower deck, standing grass stems upright for a uniform shear and forcing heavy clippings into the rear collection bag to eliminate premature discharge chute clogging. Constructed from forged high-carbon steel, the blade retains its edge when operating across dense turf, tall weeds, and slightly uneven residential ground. It supports 3-in-1 operational capabilities, allowing property owners to mulch, discharge out the side, or bag clippings without having to swap out hardware between cuts.

This blade suits homeowners maintaining small to medium residential yards with Craftsman push mower models such as the M100, M105, M110, M115, M140, and M2 series. It provides an immediate performance lift for yards with dense, moisture-heavy turf where standard factory blades struggle with deck packing. However, because it features a dedicated bow-tie center hole pattern, it cannot mount to walk-behind mowers using traditional round spindle shafts or riding tractor decks that require star-shaped arbors.

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No. 2 of 6 · UDC Parts

UDC Parts 532134149 Craftsman 42 Inch for Dual-Blade Tractor Decks

8.6/10 Our score

Best for: Riding tractors needing dual mulching blades

Pros

• Convenient two-pack set
• Long 7-1/16 inch cutting edge
• Broad tractor deck compatibility

Cons

• Requires 5-point star spindle

The UDC Parts 532134149 Craftsman 42 Inch comes as a packaged pair of replacement blades configured for 42-inch riding tractor decks that utilize a twin-blade layout. Each individual blade measures 21 inches in diagonal length, 2-1/4 inches in width, and 0.13 inches in thickness, featuring an integrated 5-point star center hole to mate securely with tractor spindle shafts. This set replaces numerous factory reference numbers, including the traditional craftsman 134149 blade, 532134149, 138971, 532138971, 138498, 532138498, 422719, 532424752, 424752, 21546095, 532127843, 127843, 594892701, 532422719, 577616134, 531005085, CMXGZAM110021, and CMXGZAM110136.

Equipped with an air lift measurement of 1-5/64 inches and an extended cutting edge length of 7-1/16 inches, this craftsman mulching blade design ensures that clippings circulate repeatedly across the underside of the deck before dropping into the turf. The extended cutting bevel maximizes contact area across wide grass swathes, turning standard yard clippings into fine, nutrient-rich mulch that settles cleanly beneath the canopy without clumping. The combined pair weighs approximately 3.79 pounds, providing substantial rotating mass to carry cutting momentum through tall, overgrown patches without bogging down the engine belts.

This dual-pack is tailored for operators of 42-inch lawn tractors who want a complete, matched replacement set for routine seasonal overhaul. It directly matches classic Craftsman riding models including the LT1000, LT2000 (specifically for model numbers such as 917289100 through 917289106 and 917288070), YT3000, YT4000 (such as 917.289260, 917.289261, and 917.289263), DYS4500, YS4500, YTS3000, DLT2000, DLT3000, and YTS4000. It is not suitable for single-blade walk-behind units or tractors equipped with newer 6-point star spindles.

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No. 3 of 6 · Fismiuta

21 inch Lawn Mower Blade for Round Center Spindles

9.6/10 Our score

The 21 inch Lawn Mower Blade is an aftermarket walk-behind cutter engineered specifically for machines utilizing a round circle center mounting arbor. Fabricated from industrial-grade 40MnB boron steel with full-body heat treatment, this blade is built with 35% higher impact resistance compared to standard carbon steel alternatives, helping prevent bent tips or catastrophic fractures when the cutting edge encounters hidden twigs, roots, or small gravel. It is designed as a direct substitute for the craftsman 406712 blade, along with factory cross-references 532406712, 189028, 532189028, 165833, 175064, 176135, 159267, 008020, 175052, and 406706.

To ensure smooth motor operation and reduce wear on engine crankshafts, each individual blade goes through digital dynamic balancing before receiving a protective heavy-duty powder coating. This anti-rust treatment provides a durable shield against moisture, damp grass acids, and abrasive dirt. The blade utilizes a medium-lift aerodynamic profile that generates a suction vortex under the deck, pulling flattened grass upright for a single-pass shear whether operating in mulching mode, rear bagging, or side ejection. The optimized cutting edge offers enhanced edge retention to prevent frayed, brown grass tips.

This model is the ideal choice for homeowners who operate legacy 21-inch Craftsman walk-behind mowers requiring a circle mounting hole rather than a bow-tie spindle. It provides exceptional resilience on rough ground where hidden debris is a persistent hazard. However, push mower owners with bow-tie spindles or riding mower operators needing star-hole tractor blades must bypass this model, as a circular center hole cannot securely interface with non-round shafts.

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No. 4 of 6 · Grasscool

Grasscool 138971 42 inch Deck Craftsman for Bagging and Discharge

8.6/10 Our score

Best for: Heavy bagging and rugged terrain clearing

Pros

• Thick 5/32 inch steel
• Rockwell hardness tested
• Consistent medium lift airflow

Cons

• Not for 6-point spindles

The Grasscool 138971 42 inch Deck Craftsman is a heavy-gauge replacement blade engineered for 42-inch lawn tractor decks that utilize a 5-point star spindle hub. Sized at 21 inches in length, 2-1/4 inches in width, and a robust 5/32-inch (4mm) thickness, this model replaces the craftsman 138971 blade, 532138971, 138498, 532138498, 532127843, and CMXGZAM110136. Grasscool subjected this blade to an extensive series of quality benchmarks during fabrication, including the Rockwell Hardness Test, V-bend impact evaluations, chipping tests, dynamic balance assessments, and field load checks.

Featuring a 7/8-inch (23mm) medium-lift wing profile, this blade is optimized to clear thick growth, overgrown weeds, and rough landscape perimeters. The medium lift creates stable air currents that direct clippings into a collection hopper or out the discharge deflector without creating unnecessary aerodynamic drag that pulls down tractor engine revolutions. The cutting edges come factory-painted to prevent oxidization on the shelf and provide handling safety during assembly, with the protective paint layer peeling back cleanly during initial blade engagement to reveal the sharp ground edge.

This blade is designed for rural property owners and homeowners operating 42-inch Craftsman riding tractors who demand extra blade thickness when clearing rugged turf. It fits riding models including the LT1000, LT2000, T110, DLT3000, T210, T2200, YT3000, YTS3000, T3000, T130, and YS4500. Owners must verify their current tractor spindle pattern before purchasing, as certain configurations of the T110, LT1000, and LT2000 utilize a 6-point star shaft that will not accept this 5-point star design.

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No. 5 of 6 · Grasscool

Grasscool 42 inch Lawn Mower Mulching for Fine Turf Recirculation

8.6/10 Our score

Best for: Lawn tractors focused on fine mulching

Pros

• Aggressive 1-1/16 inch lift
• Versatile 3-in-1 cutting action
• Handles damp grass well

Cons

• Single blade pack

The Grasscool 42 inch Lawn Mower Mulching blade provides dedicated 3-in-1 functionality for 42-inch tractor cutting decks. Measuring 21 inches long, 2-1/4 inches wide, and 9/64 inches (3.5mm) thick, this component incorporates an aggressive 1-1/16-inch (27.5mm) aerodynamic lift designed to generate high-volume air circulation. It serves as an exact OEM replacement for part numbers 134149, 532134149, 422719, 424752, 777134149, and 138971, mounting via an industry-standard 5-point star pattern.

The curved geometry of this mulching unit suspends severed grass blades inside the cutting deck chamber, allowing the cutting edges to strike clippings multiple times. This repeated processing reduces grass, fallen leaves, and small twigs into fine mulch that falls evenly between grass blades, decomposing rapidly into natural soil fertilizer. In bagging applications, the aggressive lift propels heavier clippings through the discharge opening, preventing damp grass clumps from clogging deck channels during early morning maintenance sessions.

This blade is best suited for homeowners prioritizing lawn fertilization and pristine grass clippings reduction across expansive lawns with a 42-inch deck. It fits Craftsman models such as the LT1000, LT2000, YT4000, DLT3000, and DYT4000. Because it is sold as a single unit, tractor owners performing a complete deck service must purchase two blades to replace both positions. It does not fit walk-behind decks or machines utilizing round arbors.

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No. 6 of 6 · UDC Parts

UDC Parts 532138971 138971 Craftsman 42 for High-Velocity Airflow

9.2/10 Our score

Best for: Riding mowers needing high-velocity airflow

Pros

• Pre-sharpened high-strength steel
• One-year product support
• Durable protective safety coating

Cons

• Shorter 3-5/16 inch cutting edge

The UDC Parts 532138971 138971 Craftsman 42 is a high-lift replacement blade built for 42-inch riding mower decks that need powerful discharge force. Fabricated from premium high-strength steel, the blade spans 21 inches from tip to tip diagonally, with a 2-1/4-inch body width, a 15/16-inch lift wing, and a dedicated 3-5/16-inch sharpened cutting edge. It comes pre-sharpened from the factory with a protective safety finish and is backed by a 1-year product support window covering manufacturing defects. It replaces OEM part numbers 138971, 532138971, 127843, 138971X431, 532127843, 138498, 532138498, 134149, 532134149, 424752, 532424752, and 531005085.

The high-lift contour of this blade generates elevated air velocity beneath the mower shroud, making it particularly effective at ejecting wet grass blades, clearing dense spring growth, and feeding twin-bagger grass-catching attachments without clogging. The structural rigidity of the high-strength steel dampens high-speed flex, maintaining a flat plane across both sides of the 42-inch deck for a level cut that prevents scalping or irregular striping across lawn contours.

This high-lift replacement suits owners of Craftsman lawn tractors who struggle with grass packing underneath the deck when side-discharging or running a rear collection bag. Compatible tractors include the DYT4000, YT4000, DYS4500, YS4500, YT3000, YTS3000, DLT2000, DLT3000, LT1000, and specific LT2000 configurations (such as model series 917289100 through 917289106). It relies on a 5-point star center hole, so it cannot be installed on walk-behind push units or 6-point star tractor spindles.

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