Lawn mower blade adjustment. Getting the Best Lawn Mower Cut Quality

Mower Blade Guide

When you look at your mower blade from the end, if the underside of the cutting edge is not flat to a table (parallel to the ground or center section), that will alter the angle of your grind. This is a tilt or twist forward, similar to a propeller. If you have a blade like that, you will want a Model 5005. The 5005 gives you the ability to easily adjust the grinding angle to compensate for the altered cutting edge angle. The video below goes into more detail. After reviewing the information below, if you are still unsure about your blade geometry, please contact us and we will help you choose the right model for your mower blades.

Blades With Potential Issues

We have encountered some mower blade styles that have issues being mounted in our vise. If you have one of these, you should check in with us first.

• Some eXmark 48” and smaller deck mowers have bi-level mulching blades where the cutting edge runs all the way into the center of the blade, beyond the center hole. This will cause mounting issues in our vise system that we do not yet have a solution for.
• Some mower blades have raised edges on the sides in the center mounting area. Not all, but some Toro, Snapper, and Cub Cadet blades fall into this category. There are other brands that may have this geometry as well. This causes issues but can be overcome by backing the vise screws out to raise them up so the blade will fit under them.
• Snapper Ninja mower blades are not able to be sharpened in our current units. We have not been able to create an adapter that will allow you to grind on the 4 blade edges.
• John Deere makes a mower blade for some older series of tractors that is too wide to fit in our jigs. These blades have a circular center hub that is 4 inches wide. We do not have an adapter or mounting solution for this type of mower blade.
• Dixie Chopper blades with the X—Blade system have raised centers that are stamped at an angle. This causes mounting issues in our vise system. We now have an additional adapter that can be used to properly mount the X-blades in our system.
• Honda riding lawn tractor mulching blades have a shape that will cause issues in our jigs. We have not been able to test or accommodate these blades yet. We do have an adapter for the Honda walk behind Microcut Twin Blade Sets.

Standard Mower Blades

The standard blade, as we refer to it, doesn’t have any altered angles along the cutting edge. It’s straight and simple. If you are looking to grind a 30 degree edge on these blades, you only need the Model 5002. If you want more angle options and versatility, check out the Model 5005.

John Deere Blades

John Deere mower blades can look deceptively like standard straight blades. But many, if not most of them, have a significant tilt or twist forward in the cutting section, so it is not parallel with the center section. This will alter the angle of the grind, so a setting beyond 30 degrees is necessary to compensate for the tilt. Our Model 5005 is the only jig we provide that makes it easy to choose steeper angle settings. Many John Deere customer have told us they needed to adjust their 5005 all the way to the 45 degree setting.

If the blade is used or worn, or has been previously sharpened, the angle may be beyond 45 degrees to the ground. If this is the case, it will take extra grinding to reset the angle. 45 degrees is the maximum angle adjustment in that direction. We have not found any new John Deere blades that needed an angle setting beyond 45 degrees.

John Deere also makes a mower blade (pictured above) that is too wide to fit in our jigs. These blades have a circular center hub that is 4 inches wide. We do not have an adapter or mounting solution for this type of mower blade.

Gator Mulching Blades

Gator mulching blades look more complex because of the mulching fins. But the cutting edge is the only part that needs sharpened. We have found that, due to a slight tilt forward along the cutting edge, the 35 degree setting is best to keep the factory edge on most Gator blades. We have found that most Ferris blades also have a slight tilt forward and work best with the 35 degree setting as well. The Model 5005 gives you the ability to grind at that angle.

Commercial Bi-level Mulching Blades

Bi-level mulching blades are a little more tricky. The outside cutting edge is parallel to the mounting surface. But the inside mulching section edge is raised and stamped at a different angle. We created the Model 5000 specifically to handle these. With a simple flick of the wrist, you can switch between the 30 degree setting on the outside edge or the 15 degree setting for inside mulching edge. In many cases, the Model 5005 is the better choice due to angle variances. Please read the text below …

If the underside of the outer cutting edge is not flat or parallel to the ground or the mounting section of your blade, it will alter your grinding angle. If that is the case, you will need a Model 5005 to compensate for the altered cutting edge angle.

Twisted High Lift Blades

We used to refer to these as high lift blades. But some mower blades are considered high lift without having the twisted end that makes these unique. That twist on the end alters the angle of the cutting edge. Since the cutting edge angles upward and isn’t parallel with the mounting surface, there needs to be an adjustment to compensate for that angle. The Model 5005 gives you the angle adjustments needed to fine tune your grinding edge to your preference. We see this type of blade on a lot of John Deere mowers. But there are other brands that incorporate a twisted high lift blade as well.

Honda Mower Blades

Honda Quadracut and MicroCut Twin Blade sets have a unique design and shape. We have fabricated an adapter so these blades can be mounted in our jigs. To match the factory bevel, we recommend the Model 5005 in conjunction with the Honda Adapter.

Counter-Rotating Mower Blades

Some mowers use blades that rotate in the opposite direction. We have heard these referred to as left-hand, counterclockwise, and counter-rotating blades. These will have the cutting edge on the other side of the blade. To adjust for this, all of our current Generation 2 models have extended guide arms. This gives you the extra range of motion needed to reach the cutting edge of your counter-rotating blades at the the bottom of the jig. We have seen these types of blades on many Walker mowers. But they are not exclusive to that brand. The 35 degree setting worked well with the Walker blades we have tested. For that reason, if you are planning to sharpen Walker mower blades, we recommend the Model 5005.

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Getting the Best Lawn Mower Cut Quality

Cutting the lawn has more purpose than making tall grass short. It’s about crafting landscapes that bring pride, landscapes that host parties and landscapes that literally work for you. By delivering superior cut quality for your clients, your reputation as a sharp landscaper will help retain current clients and be a selling point for new ones.

Read the following tips to learn how to get the sharpest looking landscapes. On a zero turn lawn mower, there are both adjustments and techniques landscapers can make and perform to ensure a smooth, even and appealing result with each mowing.

Adjust lawn mow​​​er deck pitch

Fine tuning a mower deck enables the aerodynamic design of the cutting chamber to lift grass, cut it evenly and discharge it effectively.

What is mowe​​​r deck pitch?

Lawn mower deck pitch, or sometimes referred to as, rake, is the tilt of the mower deck from front to back. Forward deck pitch creates an air seal at the front of the deck when the blades are rotating. This seal limits air entry into the cutting chamber to the rear of the deck, allowing the aerodynamic design of a Gravely lawn mower deck to maximize grass lift and cut evenly. This design results in a superior cut quality and an even discharge that’s less likely to clump.

For most effective results, a lawn mower deck should have a pitch, or height difference of 1/8-inch to 1/2-inch between the front of the deck to the back of the deck. Naturally, this makes the sweet spot about 1/4-inch of pitch, depending on the mower model. In any case, the front of the deck should be pitched lower than the deck rear. Be careful not to pitch too much that you start scalping lawns.

How to adjust l​​awn mower pitch

All Gravely decks are built so their owners can adjust deck pitch quickly and easily. There’s no special tools or mechanical training required to complete this procedure, either. Just a couple wrenches and a few pieces of hardware. Before you begin, park the mower on a flat, level surface, stop the engine, remove the key, check that the tire pressures are equal and grab a tape measure.

Check ​pitch

As directed in the operator’s manual:

• Raise the mower deck to a cutting height of 3.5 inches.
• Manually and carefully turn the blades so they’re positioned front to back. When manually turning blades, always grab the dull edge of the blade.
• Measure:
• The distances between the front tips of the outer blades and the ground.
• ​The distances between the rear tips of the outer blades and the ground.
• If front measurements are lower than the rear measurements by less than 1/8 inch or more than 1/2 inch, adjust pitch.

Adjust pitch

Deck pitch can be adjusted by lowering the front of the deck, raising the rear of the deck or a combination of both. Be sure to make adjustments so that the distances of your final measurements at the front of the deck accurately reflect the cutting height of 3.5 inches that was set earlier.

​​T​​o lower the high side of deck:

• Loosen jam nuts against deck lift links.
• Turn adjustment bolts counterclockwise.
• Retake measurements and continue adjustment, if necessary.
• Tighten jam nuts against deck lift links.

To raise the low side of deck:

• Loosen jam nuts against deck lift links.
• Turn adjustment bolts clockwise.
• Retake measurements and continue adjustment, if necessary.
• Tighten jam nuts against deck lift links.​

After pitch adjustment is complete, check deck level.​

Leveling yo​​ur mower deck

Level the mower deck to ensure grass cutting height is even across the width of the deck. This will help ensure a smooth and seamless side-by-side blend between each row of freshly cut grass.

What is lawn mower deck leveling?

This is easier to understand than deck pitch. Deck leveling is simply making the cutting height on the left side of the deck even with the cutting height on the right side of the deck. In all cases, decks should be level with as little variance between each side of the cutting deck as possible. No variance between the left and right side of the deck is best.​

How to level the mower deck​

Leveling a Gravely lawn mower deck is done the same way as pitching a Gravely mower deck, except it’s adjusting the deck height from side to side, not back to front. Same components and tools with pitching a mower deck, and as before, start with the unit parked on a flat, level surface, inflate the tires to specification and grab a tape measure.​

Check mower deck level​​

As directed in the operator’s manual:

• Raise the mower deck to a cutting height of 3.5 inches.
• While wearing thick, sturdy gloves, manually and carefully turn the blades so they’re positioned side to side. When manually turning blades, always grab the dull edge of the blade.
• Measure:
• The distance between the left blade’s left cutting edge and the ground.
• The distance between the right blade’s right cutting edge and the ground.
• If the distance between the left blade tip and the ground is 3/16 inches greater than or less than the distance between the right blade tip and the ground, level the deck.

How to level your la​wn mower deck

As directed in the operator’s manual

• Loosen jam nuts against deck lift links.
• Turn adjustment bolts counterclockwise.
• Retake measurements and continue adjustment, if necessary.
• Tighten jam nuts against deck lift links.

• Loosen jam nuts against deck lift links.
• Turn adjustment bolts clockwise.
• Retake measurements and continue adjustment, if necessary.
• Tighten jam nuts against deck lift links.

How to sharpen lawn ​mower blades

Same as with dull knives or scissors – they don’t cut efficiently and results in duplicate effort. On a mower, dull blades leave behind stragglers and require the terribly inefficient practice of mowing the same rows twice.

Dull blades may require a total replacement, which isn’t bad since new blades are relatively cheap and easy to replace. However, if the blades aren’t worn too far, they can be sharpened without spending money on new blades. Be aware that blades should not be sharpened if more than a half-inch of the blade material is worn away (by previous sharpening or wear) or if the air lift is eroded. If the air lift is eroded, blades can no longer lift grass effectively and cut evenly. Blades that are bent or broken should be discarded.

• Read the safety instructions and the procedure instructions in the unit’s operator’s manual.
• Remove the mower deck according to the instructions in the operator’s manual.
• Remove the blades according to the instructions in the operator’s manual.
• File or grind an equal amount of blade material from each cutting edge until sharp. Do not change angle of cutting edge or round the corner of the blade.
• Slide the blade onto an unthreaded bolt and hold the bolt horizontally. Position the blade horizontally and check for blade balance. This is critical. If the blade moves, sharpen the heavy end until the blade remains balanced in a horizontal position on the unthreaded bolt.
• When the blade is sharpened and balanced adequately, reinstall it under the mower deck and torque it to the specification listed in the operator’s manual.
• Reinstall the mower deck.

Cleaning your mo​​wer d​​eck

Mower decks packed with grass clippings, dirt and debris can damage your mower, affect cut quality and hurt lawns. Grass, dirt and debris holds moisture that corrodes bare metal on the spindles and mower blades, weakening them. Additionally, grass-packed cutting decks can harbor fungi and bacteria that can spread to other lawns and damage them.

Grass buildup around the discharge area can prevent clippings from discharging evenly and could lead to clumping. Grass buildup under the deck can also affect the aerodynamics of the cutting chamber, disrupt the air lift under the deck (detailed in What is mower deck pitch?) and affect the cut quality.

Good lawn mo​​​wi​​ng techniques

Sometimes, getting a better cut quality can be achieved by breaking a few bad habits like mowing too fast, mowing in the same pattern and cutting grass too short.

Why you shouldn’t mow t​​oo fast

For busy landscapers, efficiency is important. And while landscapers will find many creative ways to shave time off each job, patience on the jobsite yields better results. Driving faster than the mower blades and deck can process overwhelms the deck and leaves behind stragglers and clumping. Slowing down the drive speed of a mower allows the blades enough time to lift, cut and discharge grass clippings evenly.

Why you should mow ​​in different patterns

After mowing the same properties, landscapers will learn the best way to navigate through their clients’ properties and will sometimes stick to one efficient mowing pattern. However, mowing in the same pattern is bad for lawns.

Grass is like hair. If it’s accustomed to being pushed in the same direction, it learns which way to fall. After mowing in the same paths cut after cut, grass falls to one direction and doesn’t stand straight up, making it more difficult for the mower to lift the grass and cut it evenly.

Additionally, mowing in the same pattern creates ruts. The weight of a mower driving over the same rows with each mowing causes the soil under a mower’s wheels to become compacted. As soil compacts, it restricts water, air and nutrients from reaching grass roots, leading to grass discoloration in those mower tracks.

To avoid these issues, landscapers should mow in a different pattern that crisscrosses the pattern of the previous mowing.

Why you shouldn’t cu​​t grass too short

Grass that’s kept longer grows healthier.

Grass that’s cut too short becomes stressed because it uses its energy re-growing what was just cut instead of growing its root system. Longer grass makes healthier lawns because longer grass has deeper root systems which access moisture and nutrients more effectively. Additionally, longer grass helps prevent the ability for weeds to take hold in the soil and germinate because tall grass blocks sunlight from those weeds.

Landscapers should cut no more than one-third of the length of grass with each mowing.

Best mowers for good cu​​t ​​quality

Performing service and adjustments on any lawn mower makes a big difference in cut quality, but you’ll never get the best cutting quality without having the right equipment. Consumers have numerous choices in a commercial lawn mower, but they’re not built alike.

Gravely commercial lawn mowers are designed for landscapers. Not only is a Gravely durable, reliable and comfortable, but each Gravely is designed to deliver superior cutting results.

Strong de​​ck stability

As opposed to decks that shake excessively when cutting, Gravely decks are sturdy and move with the contours of each landscape, ensuring an even cut.

Cutting deck di​​mensions

The deep depth of a fully fabricated Gravely commercial mower deck processes greater volumes of grass faster with reduced need to compromise speed for quality on the jobsite.

Superior deck aero​​dynamics

Grass is lifted and discharged evenly and effectively, meaning there’s less chance for stragglers and clumping.

Constant belt tension

Gravely’s trademarked constant belt tension, or CBT, applies the same tension to a brand new mower belt than it does to an older, stretched mower belt. This ensures consistent blade tip speed and cutting results throughout the life of the belt, even as it wears.​

Lawn mowe​​​r dealers near me

Ready to learn more about the machines that have been shaping the American landscape for over a century? Stop by your local Gravely dealer to explore Gravely’s full product lineup and to get replacement parts like belts, blades and more. Add a Gravely lawn striper kit this season to enhance each lawn by giving it that professional, finished look.​

How to Level a Mower Deck (4 Easy Steps)

Leveling your lawn mower deck is a crucial part of lawn mower servicing. An out-of-level deck will result in an uneven cut with what look like “steps” in your lawn. Modern lawn tractors and zero-turn mowers allow you to adjust the deck relatively easily so that you can achieve a perfectly even cut lawn. Follow my step-by-step guide below to level your riding mower deck.

Signs that You Need to Level Your Mower Deck

Here are common signs you can look out for to identify if your lawn mower deck is not level. You’ll be able to notice potential issues with the deck by simply inspecting the cut your lawn mower is making.

• One side of the lawn mower is cutting lower than the other
• Steps in the lawn between cutting strips
• The grass isn’t being cut well, even with sharp blades

The Equipment You’ll Need On Hand to Level Your Riding Mower Deck

You’ll need a level surface to work on to level your mower deck accurately. The adjustments are fractions of an inch, so use the most level work area you can find. Then you’ll want to collect the following tools:

How to Level a Mower Deck (Step by Step)

The principles and preparations are the same when leveling zero-turn decks or lawn tractor decks. To achieve accurate leveling, you’ll need to follow these steps.

Preparing the Lawn Mower

To start leveling, you’ll need to have a safe and level lawn mower. Begin by positioning your lawn mower on your level surface. Next, apply the brake and raise the cutting deck to full height. Next, remove the spark plug, so the lawn mower cannot start.

With the lawn mower on level ground, you’ll next want to equal the tire pressure. Take your pressure gauge and measure the front tires. Inflate the front tires so they are of equal pressure, matching the tire inflation recommendations stated on the tire. Once done, you can repeat this for the rear tires. Additionally, your tire sizes must match. If you have odd tires, you’ll never be able to level your mower deck.

Inspecting the Blades

The next step in the leveling process is checking that the blades are straight. First, position the blade so that the tips point toward the sides of the mower instead of toward the front and back.

Then measure the outer tip from the ground up to the blade. Next, rotate the blade 180 degrees and measure the opposite blade tip. Both measurement results should match. If they don’t match, your blade is bent and needs replacement. Repeat this process for each blade on your deck.

Adjusting the Lawn Mower Deck Side-to-Side

We will adjust the deck in two stages. The first step is the side-to-side adjustment. Position the blades so the tips point towards the sides of the mower. Next, measure the outer tips from the ground up to the blade for both the left and right blades using your measuring device and write down the results.

Your end goal is to have both sides of the deck measuring within ⅛ inch of each other. You’ll only need to adjust one side of the deck to achieve this. Using your wrench, adjust the lift link adjustment nut on one side of the lawn mower. Usually, clockwise is up, and anti-clockwise is down. You’ll raise or lower the deck by making minor adjustments to the adjustment nut.

Alternate between adjustments and measuring the blade tip height. Once you have achieved the desired height, confirm by remeasuring both sides of the deck.

Adjusting the Lawn Mower Deck Front-to-Back

The second step is leveling the mower deck front-to-back. The front of the deck should be ⅛ – ½ inch lower than the back.

Start by positioning one of the blades, so the tips point towards the front and back of the mower. Then measure the height from the ground up to the blade of the tip facing towards the front. Next, measure the height from the ground up to the blade of the tip facing towards the back. Note the results of both measurements.

Grab your wrench and locate the front lift link adjustment nut. Your adjustment will alter the height of the front of the deck. Your goal is to get the front to be ⅛ – ½ inch lower than the back.

Adjust the nut clockwise if you need to raise the front of the deck. If you need to lower it, make anti-clockwise adjustments. Once done, remeasure the blade tips pointing front-to-back and confirm the mower deck is level within the desired range.

What if You Don’t Need to Make an Adjustment?

When you measure the blade tips, you may find that you don’t need to make any adjustments. You probably fixed the leveling problem by simply inflating the tires to equal pressure and ensuring the blade is straight. This shows you that proper tire pressure and good-quality blades are essential to achieving a perfectly cut lawn.

About Tom Greene

I’ve always had a keen interest in lawn care as long as I can remember. Friends used to call me the lawn mower guru (hence the site name), but I’m anything but. I just enjoy cutting my lawn and spending time outdoors. I also love the well-deserved doughnuts and coffee afterward!

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How to Measure Lawn Mower Cutting Height

Everyone loves a beautifully cut, lush, healthy lawn. However, it can be difficult to know the correct height to cut your lovely lawn and how to set your mower blades just right to achieve that height.

Below you will find some tips and facts on how to properly gauge the height of your mower blades and what length different grass types should be cut.

What do the numbers mean on a lawn mower?

Often, a mower will have a set of numbers (1,2,3) or letters (a,b,c) on the wheel; these are known as the blade height gauge. These settings do not necessarily mean inches. You need to consult your owner’s manual to find out exactly what they mean.

One method of knowing precisely what height your mower is set at is to place it on a hard, flat surface such as a driveway or sidewalk. You must measure from the blade to the ground to determine the height your mower is set at.

When doing this, take safety precautionary measures first. Most mowers these days have an automatic shut-off switch if you are not touching the handle. However, it is wise to remove a spark plug before placing your hand under the mower’s deck to measure the height.

Once it is safe, open the door or trap and measure the blade to the ground. This will tell you the precise distance that your mower is set at. Now, depending on the type of grass you have will help you determine the proper height to set the mower.

How do I measure grass height?

There is a standard “Rule of Thumb” when it comes to the heights of your grasses depending on the season and type of grass. Generally speaking, during cool seasons – early spring and fall – you should maintain a height of 2 ½” to encourage root growth and prevent weed growth.

During late spring and summer, when the weather is warmer, grass should be kept at 3” to retain moisture and keep the color.

Here are the heights that some specific types of grasses like to be mowed at:

• Tall fescue between 2 inches to 3 ½ inches
• Kentucky bluegrass between 2 and 3 inches
• Bermuda grass between 1 and 2 inches
• Zoysia grass between 1 and 2 inches
• Buffalo grass between 2 – 3 inches

When mowing, take no more than 1/3 of the height of the grass blade. If too much is taken off, this is called scalping and will cause grass root systems to weaken and weeds to grow rapidly.

There are many ways to measure lawn height. The simplest method is to take a measuring stick and measure from the ground to the surface of the grass blade. Do this multiple times throughout your lawn to get a good average. (This will also tell you where your grass grows slower or faster.)

If you prefer a more modern method of measurement, there are devices available for purchase that will measure the height of the grass blade accurately. These include electronic meters and probes.

Should lawn mower wheels be the same height?

Deck pitch is very important. The wheels should be even from side to side. However, you want the front of your mower to be about ¾” lower than the rear end of the mower. On most lawnmowers, the settings will reflect the need for that height adjustment.

So, if you are using setting #3, you can adjust all of the lawn mower wheels to setting #3, and the mower should be good to go.

What height should a lawn mower be set at?

Often, the tallest setting on your mower will be 3”. So, remember this when adjusting your lawn mower height. Depending on what time of year you are mowing your yard, cool seasons, or warm seasons, determine what height your mower should be set.

As you have read in the earlier paragraphs, proper height is determined by the type of grass and time of year. Mowing your grass to the correct height will encourage deep root growth, retain moisture, prevent weeds, and keep your lawn looking healthy and green.