12 Reasons a Craftsman Mower Cut is Bad or Uneven

You purchased a Craftsman mower based on the manufacturer’s reputation and experience building mowers. Your Craftsman usually provides you with a good quality cut, but the last time you mowed your yard looked terrible.

There can be many different reasons your mower will begin to cut unevenly. Most of the causes resulting in a bad cut can be easily resolved and fixed by you.

A Craftsman lawn mower may leave you with a bad or uneven cut when your tire pressures are incorrect; your deck has damaged components; your mower blades are dull or bent, or your mower deck is plugged with grass and not level.

Take caution when working on your mower deck and with sharp mower blades. Always remove your ignition key and spark plug boot(s) before performing any work on your mower. You do not want your mower to unexpectedly start while you are under the deck.

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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

Types of Cut Quality Problems

Scalping	Close cut in areas of the lawn	Low tire, uneven lawn, unlevel deck, deck height too low
Step Cut	Ridges in the lawn	Low tire, unlevel deck, bent mower blade, spindle damage, wrong blade installation
Streaking	Strips of uncut grass	Worn blades, dull blades, clogged mower deck, incorrect mowing paths, mowing too fast, engine speed is too low.
Stringers	Patches of uncut grass	Worn blades, dull blades, clogged mower deck, mowing too fast, engine speed is too low.

Your Craftsman Has a Bad or Uneven Cut (12 Reasons)

Blade is Worn or Dull

If you find you’re leaving strips of uncut grass or the grass looks brown a couple of days after you mow the lawn, you may have extremely worn or dull blades.

When your blades are worn, they don’t provide clean cuts to your blades of grass. Dull blades beat up the grass so the grass is bruised and turns brown.

Read more about how to keep your mower blades sharp by using professional services or sharpening your Craftsman blades yourself.

Tire Pressures are Not Correct

Most people assume a bad cut is due to something in the lawn mower deck. They forget or don’t realize it could be the result of a low tire.

When the tires are not of equal pressure, the mower deck will not sit level. This is one of the first things you should check before measuring for bent blades or an unleveled mower deck.

Blade is Bent

A bent mower blade can also make your mower leave you with an uneven cut. If you impact something very hard, it can be quite obvious you have a bent blade.

Other times, it is harder to see a bent blade. There are two ways you can check whether or not your blade has a bend to it:

Method 1: Remove the blade and lay it on top of a new blade. This is a good way to verify a bent blade, but you will have to take the time to remove your mower blade. If you prefer not to remove your blade, you can try the next method.

Method 2: Park your Craftsman mower on a flat-level surface. Measure one side of the blade from the ground to the blade tip. Record the measurement.

Next, rotate the blade 180 degrees and measure the other side of the blade from the ground to the blade tip. If the measurements are greater than a 1/8” difference, you need to replace your mower blade.

Never attempt to straighten a bent mower blade to reuse it. When you do this, the metal is compromised and becomes weakened.

It is possible for the weakened area to break off and fly out of your mower deck at high speeds. This could cause injury or damage to people, pets, or objects in the area.

Blades are Installed Incorrectly

Craftsman mower blades must have the sail pointed toward the deck. Many times, the mower blade will be stamped to indicate which side of the blade goes up and which side of the blade faces the ground.

Installing your blades upside down will beat up your grass and can cause damage to your spindle housings.

In addition to making sure your blades are installed correctly, you will need to make sure your blades are balanced. This means the weight on one side of the blade is equal to the weight on the other side of the blade.

The most accurate way for you to check this is by using a blade balancer. Another method is to hang your blade on a nail in the wall to verify it sits level.

When one side of your blade is heavier than the other, you need to shave off some of the metal to make it lighter and equal weight to the opposite end of the blade. An unbalanced blade can cause spindle damage and excessive vibration.

Mower Deck is Plugged with Grass

Grass and dirt will eventually build up under your mower deck. Without regular cleanings, substantial grass can get clogged in your deck to cause you to have an uneven cut.

Craftsman designs their decks to work with their spinning mower blades to create air movement and suction in the deck. This suction lifts the grass so the blades can give your lawn an even cut.

Clogging of grass can become worse when mowing in wet conditions. It can also leave clumps of grass in your yard. Avoiding wet grass and cleaning your deck regularly will keep the area under the deck open for the blades to move and create good air movement.

Mower Deck is Not Level

Measure each corner of your mower deck to confirm your deck is level. Make sure your Craftsman is parked on a flat-level surface when taking the measurement.

Refer to your owner’s manual for directions on how to level your deck from side-to-side and front-to-back as the measurements and procedures can vary by model.

Ensure your deck has the correct pitch where the front of the deck sits slightly lower than the back of the deck.

Blade Spindle is Bent

Next, you’ll want to check to see if your spindle is bent or if the bearing is damaged in your spindle housing. In order to do this, put on a pair of heavy gloves to protect you from the sharp blades. Grab a hold of each side of the blade and rock up and down.

If you feel any movement or hear a knock, you will want to remove and inspect your spindle housing for damage. Movement and a knock usually mean you will need to replace the bearing in the housing.

Deck Belt or Pulleys are Worn

Turn each pulley on the deck slowly to see if you can feel any resistance or hear any noise. Replace any pulleys that don’t rotate smoothly or you hear a noise coming from the bearing. Your deck belt needs to be in good condition without cracks and wear.

Make sure your belt sits securely around the pulleys. When your pulleys or deck belt are bad, they can fail to turn your blades at their top speeds.

Engine Speed is Too Low or Ground Speed is Too Fast

Your mower deck needs engine speed in order to cut at its best. Run your mower at full throttle to keep your blades spinning fast. In addition to running your mower at full throttle, you must also gauge your mower’s ground speed.

Adjust your ground speed to your conditions. For example, if you are mowing thick, tall, or wet grass, you will need to slow down your ground speed so you don’t put too much of a load on your engine.

Moving too fast across your lawn can also cause you not to get a good cut as your mower may be pushing over some of the grass instead of standing it tall.

Incorrect Overlapping Mowing Path

In the past, I have tried to make fewer mowing passes in my yard to get my cutting done quickly because I didn’t have much time. Well, I did get done faster, but when I looked back at my lawn I saw thin strips of grass that I missed because I didn’t properly overlap my passes.

Make sure you are not causing your mower to leave strips of grass by doing the same thing I did and not properly overlapping the cutting paths.

Deck Shell is Damaged

A deck shell can get tweaked by running your mower into objects like trees, rocks, and other hard surfaces. The deck shell is formed to create a suction to give you a good cut. If the deck has been damaged, your cut could also be compromised.

You’ll need to try to repair your deck or you may need to replace it altogether. If you do replace the shell, you will have to move the components from your old deck onto the new deck shell.

Your Lawn is Uneven

When your lawn is uneven and bumpy, your mower deck can scalp your lawn leaving you an uneven cut. You will either have to deal with this or you can get a lawn roller and try to even it out.

Mowing ditches with a wide format mowing deck can also provide a bad cut or a stair step type cut because it isn’t able to follow uneven curves. It’s best to use a push mower with a smaller format deck in these areas.

Quick Reference Chart

Cause for Uneven Cut	Solution for Uneven Cut
Mower blade is dull or worn	Sharpen blade. Replace with new blade when needed.
Incorrect tire pressures	Check tire pressures and bring to the correct level
Blade is bent or damaged	Replace mower blade
Blade is incorrectly installed	Remove and install with the blade sail point upward
Deck is packed with grass	Scrape the deck
Deck is not level	Level the deck from side-to-side & front-to-back
Damage to spindle or spindle housing	Replace damaged spindle or housing
Bad deck belt or pulleys	Replace worn belts and pulleys
Engine speed is too low	Run your mower at full throttle
Ground speed is too fast	Mow at correct speeds for your mowing conditions
Incorrect overlapping of paths	Overlap paths so strips of uncut grass are not left
Damaged mower deck shell	Repair or replace your mower deck shell

Your Craftsman Deck Is Lower on One Side

Your mower may be lower on one side because your mower deck is not level or one of your tires has a low air pressure. Fill your tires with the correct pressure so the tires on each side of the mower have equal pressures.

Refer to your owner’s manual for the deck-leveling procedure for your Craftsman mower. The procedures for leveling a deck can vary with some Craftsman models.

Your Craftsman Mower Leaves a Row of Grass

A row of grass can be left behind when mowing because you are not running your mower at full throttle, your mower blades are worn, your deck shell is damaged, your mower deck is clogged or you are not properly overlapping your cuts.