Lawn Mower Blades: The Ultimate Guide (Types, Measuring, and )
Purchasing replacement blades for your lawn mower is a relatively easy task if you know your lawn mower blade’s part number. If you have your lawn mower’s model and serial number, referencing that mower’s model and serial number parts diagram is another fool-proof way to purchase the correct blade.
But, what if you don’t have any of these part numbers to reference? How do you determine which blades will fit your mower?
By the time you are finished reading our Ultimate Guide to Lawn Mower Blades article, you should have all the info you need to purchase a blade that will work perfectly with your lawn mower.
How to measure lawn mower blades
We’ll get into the various types of lawn mower blades further into the article (skip to view types of lawn mower blades). First, we will walk you through measuring the blade on your lawn mower to determine which size blade you need.
How to sharpen lawn mower blades THE CORRECT WAY ( Angle grinders will destroy your mower blades)
Measure mower blades diagonally
The most common mistake we see when people are attempting to measure their lawn mower blade is measuring straight across the blade. This is going to give you an inaccurate measurement!
To properly measure a lawn mower blade, measure the blade diagonally.
Center hole diameter
The next measurement you will need is the diameter of the center hole of your lawn mower blade.
If your mower blade has 3 holes, make sure you are measuring the center hole!
To measure the diameter, measure straight across.
If your mower blade does not have a circle for the center hole, you will need to determine what the shape in referred to. on mower blades without circle-shaped holes in just a second.
If your mower blade has “outside holes”
If you notice 2 holes on either side of the center hole in your lawn mower blade, you will also need to take some measurements here.
Many push lawn mowers and some other types of mowers utilize these outer holes to ensure the blades do not hit each other while in use. Many commercial lawn mowers use 2 or 3 blades, not just 1 blade.
A perfect example of this is the Exmark Commercial 30. This is an oversized 30″ wide commercial push mower that utilizes the center holes to ensure each blade is mounted in the correct position.
Once again, you will want to measure the diameter of these holes.
You will also need to measure the distance between the center of these 2 outside holes. This measurement is referred to as center to center.
Lawn mower blade center hole types
Most lawn mower blades have circles as the center hole shape. If your blade does not, here is a quick reference of other possible mower blade center hole types.
Less common but not pictured center hole types include a square and a 7-point star center hole.
Measuring your mower blades width
The width of a lawn mower blade is usually not relevant to the fitment of the blade but we wanted to make sure you knew where to measure if this is applicable to your mower.
To accurately measure the width, make sure you are measuring straight across and measuring at the widest section of your blade.
Right-hand cut vs left-hand cut blades
Believe it or not, the cutting edge is not on the same side for all lawn mower blades.
Right-hand cut lawn mower blades are overwhelmingly the most common type.
Left-hand cut blades can be found on some mower’s manufactured by Kubota, Woods, Walker, and others.
Lawn Mower Blade Thickness
It is recommended to stick with the specs of the blade that came stock on your lawn mower. If for whatever reason you cannot determine the OEM blade part number, don’t stress about the thickness of the blade. It is not a huge deal, although using a blade that is too thick could lower the RPMs to a point where cut quality is lost.
As you might expect, blade thickness is measured by measuring the top of the blade to the bottom.
If you are bending a lot of blades, you may want to purchase a thicker lawn mower blade or just stop hitting rocks! Believe me, I’ve had 100 employees in my lawn care business over the years and completely understand if you are not sure if your employees are looking at what they are cutting as they are working!
Types of lawn mower blades
Now that you understand how to measure lawn mower blades properly and the various types of center holes you may find, let’s take a look at the different types of lawn mower blades and when you may want to consider each type.
We should mention you may see “standard blade” in the description of some lawn mower blades. This is basically the middle ground between high lift and low lift lawn mower blades. It is pretty suitable for any type of cutting.
High lift lawn mower blades
High lift lawn mower blades create a lot of lift due to the exaggerated fin on the non-cutting edge side of the blade.
When to use high lift lawn mower blades:
When not to use high lift lawn mower blades:
Low lift lawn mower blades
Low lift lawn mower blades c reate little lift due to the exaggerated fin on the non-cutting edge side of the blade.
When to use low lift lawn mower blades:
- When you are cutting short grass (Grass under 3″ tall)
- When you are cutting rigid grass such as Bermudagrass
- In sandy soil conditions (see flat blades too)
When not to use low lift lawn mower blades:
Gator blades are also referred to as 3-in-1. Gator blades are often used by professional mowing companies in the fall to shred leaves as they mow. S ome companies run gator blades all year long.
Gator blades also shred longer grass blades before being discharged from the mower’s deck. Gator blades do create some lift.
When to use gator blades:
When not to use gator blades:
Mulching blades mulch the grass clippings to allow for returning the grass clippings to the soil as natural nutrients.
It is important to note, you can certainly discharge the clippings from the mower’s deck back into the lawn without mulching blades as long as you are cutting your grass on a frequent enough basis.
When to use mulching blades:
- When you are not discharging the clippings or bagging
- When you are following the 1/3 rule (only remove 1/3 or less of the grass blade each time you mow)
When not to use mulching blades:
Flat lawn mower blades
Flat lawn mower blades create zero lift due to the blade being completely flat.
When to use flat lawn mower blades:
When not to use flat lawn mower blades:
Self-sharpening lawn mower blades
To ensure this article covers all the bases, we wanted to include a new option when it comes to lawn mower blades.
Self-sharpening blades use patented technology to literally sharpen themselves as you mow. The early adopters seem to agree that these blades do in fact sharpen themselves.
Of course, these blades come with a hefty price tag as far as lawn mower blades are concerned. It will be for you to determine if they are worth the investment.
When to sharpen lawn mower blades
Factors such as how much use, what type of grass you are cutting, the length of grass you are cutting, soil conditions, and other factors will determine how often you will need to sharpen your lawn mower blades.
After finishing this article, check out our guide on sharpening lawn mower blades.
The best way to determine when you need to sharpen your lawn mower blades is by simply looking at the cut quality. This refers to the sharpness of the cut you are getting out of your blades. In the picture above you can clearly see the blades on the lawn mower that cut this grass need to be sharpened as they are tearing the grass instead of cutting it.
How to tell if a mower blade has been sharpened too many times
If you read the manuals, most lawn mower blade manufacturers recommend replacing the blades when there is 1/2″ left between the cutting edge and the fin, sail, or lift. The fin, sail, or lift is referring to the part of the blade that is angled up.
If you continue to mow with less than 1/2″ of material left, you are putting yourself and others in danger as there is a great possibility this blade could fail and send a piece of the blade flying from your mower. Please take this recommendation seriously!
Even if no one is hurt if this occurs, you very well could be on the hook for property damage costs.
When to replace lawn mower blades
At some point, lawn mower blades can no longer be sharpened and will need to be replaced.
You may need to replace your lawn mower blades because you have sharpened them too many times and have removed too much material from the blade.
Other reasons you may need to replace your lawn mower blades are much more obvious.
For example, if you bend your lawn mower blade, it should be replaced. Please do not attempt to bend it back to being straight once again. The integrity of the blade was lost as soon as it was bent.
Other reasons to replace your lawn mower blades include large chunks missing due to hitting an obstacle or hairline fractures. You should always inspect your lawn mower blades when sharpening or if you know you just hit an object you shouldn’t have!
OEM vs Universal Lawn Mower Blades
Something worth noting about lawn mower blades is that you do not have to stick with the OEM blades that came with your lawn mower!
Some stock blades simply do not provide a great cut quality. The 2 most important factors when purchasing aftermarket blades is that you purchase blades with the same length and center hole diameter. If your blade has the additional outer holes, you need to account for these specs as well.
Above is an example of a universal replacement blade that has an elongated hole instead of a circle. You will often see this on universal blades that account for outer holes because they want the blade to fit as many makes and models of mowers as possible.
Where to purchase lawn mower blades?
Great question. You are in the right place!
iGoPro Lawn Supply has over 900 lawn mower blades in stock.
We more than likely have the blade you need and have the best price you will find online.
Go ahead and shop lawn mower blades now. We recommend searching for the blade you need by part number, but by now you are fully prepared to measure your blades and purchase the perfect replacement blade.
Lawn Mower Blade Conclusion
To wrap this up, let’s just summarize the most important information we covered.
The 2 most important things to note when purchasing lawn mower blades is the length of the blade and the center hole diameter.
Make sure you purchase a blade with the appropriate outer holes as well if your mower requires them.
Use high lift blades if you are mowing cool-season grasses.
Use low lift blades if you are mowing warm-season grasses.
Try gator blades if you are mowing long grass or would like to shred leaves as you mow.
Mulching blades should only be used with a mulching lawn mower or a lawn mower with a mulching kit installed.
Ryan is the owner and founder of Lawn Crack, LLC the parent company of iGoPro Lawn Supply. He has worked in almost every capacity within the lawn and landscape industry for small local companies, nationwide companies, and of course, owning his own lawn landscape business which he sold in 2018 before starting selling lawn and garden products online. Learn more about Ryan by subscribing to the LawnCrack YouTube Channel.
How to Sharpen Lawn Mower Blades
So your lawn is starting to take off this spring, but when you finally got out there and mowed it, did that thick green grass start looking ragged and fringed with brown? A dull lawn mower blade is the likely suspect. Read on to learn how to sharpen lawn mower blades for a clean cut every time.
How to Sharpen Lawn Mower Blades in 5 Steps
Tools You Need
- Work gloves and eye safety equipment
- A hand metal file, angle grinder, mounted bench grinder, or dedicated lawn mower blade sharpener
- A wrench to remove and reattach the blade
- A wood block
- A nail, screwdriver, or dedicated blade balancer
Prepare the Mower
NOTE: Make absolutely sure the mower can’t start by accident. Human flesh and fast blades are a terrible combination.
Gas-powered mowers: Unscrew the spark plug. Most of the time, you should be able to leave it attached via the spark plug wire. Once the spark plug is disconnected, tilt the mower on its side, making sure the air filter and carburetor are facing up. That will prevent a belch of smoke on restarting. Tighten down the gas cap.
Electric mower: disengage the cord or battery. Mark the bottom of the blade with chalk or spray paint to make sure you don’t reinstall it upside-down. Some blades are also clearly stamped “bottom” to save you this step.
Detach Mower Blades
NOTE: To sharpen the blade, first remove it from the mower. Never sharpen the blade while it’s still mounted to the mower.
In general, blades are just bolted to the deck of the mower, but the precise way they are attached can differ.
This would be a good time to head online to see if your lawn mower manufacturer has provided an online guide. Look up your mower and see if there are any quirks to detaching the blade. The guide also will likely tell you the proper size wrench to remove the nut holding the blade in place.
If the nut is stuck in too tight, try soaking it with penetrating oil or using a long-handled wrench for more torque. Wedge in the block of wood to keep the blades from turning while you loosen the nut.
Once you have the blade in hand, find the cutting edge on both sides of the blade and inspect them to see how much sharpening they need. A newer blade or one that has been kept up well could just need a few passes with the hand file or sharpening stone, but one that has been used frequently since its last sharpening may be better served by an angle grinder or bench grinder.
Follow the angle and grind on each cutting edge on each end of the blade to get a sharp edge on both sides. Dedicated lawn mower blade sharpeners make this easy, using a guide for the edges of the blades so they get the correct angle from the grinding wheel.
Oregon Products, which sells a variety of lawn-mowing products, says that a dedicated blade grinder is the best way to give a mower blade the perfect edge — sharp, but not too sharp.
“Mower blades should be aggressively sharp, but not as sharp as a razor’s edge,” the site says. “You should be able to touch the blade with your hand without getting cut.” Essentially, somewhere between butter-knife sharp and razor-sharp.
Balance the Blade
An unbalanced blade can shake the mower and potentially cause damage, so balance the blade with a few extra passes on the sharpener.
Once the blade is sharpened, make sure it’s balanced before you reattach it to the mower. This can be done by using a nail hammered into the wall of your garage or by using a screwdriver.
Place the nail or screwdriver through the blade’s center hole and see if it’s heavier on one side. If it is, give it another quick pass with the hand file or angle grinder until it’s balanced.
With your lawn mower still on its side, make sure the blade is oriented correctly, checking with the spray paint or chalk mark from Step 1. Take this chance to add some oil and lubricant to the crankshaft of the lawn mower or clean the underside of the mower deck.
Place the blade back onto the mower and tighten the hardware down to the recommended torque from your owner’s manual. Reattach the spark plug or battery and you’re ready to go.
That is, at least until those grass clippings start to look ragged and torn again.
To see whether you should sharpen your mower blade, pay attention to the lawn and how the mower is cutting. If you start to see the grass getting pulled and torn instead of cleanly cut, it’s likely time for another blade sharpening. If the blade is warped or too far gone, it may be time to purchase a new blade.
Hentschel says it only takes about a month for lawn mower blades to go dull, especially if you have seen clouds of dirt or sprays of rock shrapnel flying out from under the mower.
When to Sharpen Again
Sharpen your lawn mower’s blade at least once a year to make sure you stay on top of your lawn-care game. The frequency of resharpening depends on the level of use, but for the average person mowing a home lawn, twice a year should do the trick.
Hentschel says he’d be thrilled if folks sharpened blades at least once a year, but he recommends twice per mowing season — starting off with fresh, sharp blades in the spring and then sharpening them again around the end of June or the beginning of July to finish off the season strong.
“Once a year is way better than never,” Hentschel said.
Sharpening My Blades Isn’t Working. How Do I Know If I Need a New Mower Blade?
Here are a few indicators to look out for:
- Significant chips or dents in the blade
- If the blade is thinner
- Your lawn mower blade is bent
- The blade is still dull after sharpening
What Angle Should a Lawn Mower Blade Be Sharpened?
The most common lawn mower blade angle is 30-35 degrees. When sharpening your mower blades, it’s important to keep this 30-35 degree angle over time.
What Does a Lawn Mower Tune-Up Consist Of?
The three main components involved in a mower tune-up are the air filter, spark plugs, and oil, all of which must be changed. All you need to do is change the oil and air filter and replace the spark plug. The needed parts and supplies are available at home centers and hardware stores.
How Much Does a Lawn Mower Cost?
It depends on the size and condition of your yard as well as the type of lawn mower you want. Look at the table below to see the types of lawn mowers available and how much they cost.
Straighten, sharpen, and balance a lawnmower blade!
|Lawn Mower Type
|Robot Lawn Mower
|Riding Lawn Mower
To dive deeper into lawn mowers and their prices, read LawnStarter’s pricing guide.
Kick Some Grass
Now that you know how to keep your blades sharp and ready to go, you’re ready to keep your grass green and neat all season long. If you’d like someone else to worry about the finer points of mowing and sharpening, contact a local lawn care pro to keep your lawn cleanly cut all season long.
Stuart Kushner is a writer and aspiring product designer based in New York City. When he isn’t doing either, Stuart enjoys heavy metal music, exercise, and trying new food and drinks.
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How to tell if a Lawnmower Crankshaft is Bent?
When you mow your lawn, it is always possible that you hit a rock, a toy, or another hidden obstacle while. Such accidents can cause physical damages to the mower, and even the flywheel can break. If the mower hits or runs over something while running at high speed, both the chances and severity of physical damages can increase. One such physical damage that is not uncommon to occur is a bent crankshaft. The crankshaft connects the mower blade to the motor and rotates at a very high rpm. If the mower hits a hard obstacle, the crankshaft can slightly bend, causing problems. A bent or partly broken crankshaft has some clear symptoms that are not difficult to observe. In this blog, we will go through diagnosing a bent crankshaft and how to fix one.
How to tell if a Lawnmower Crankshaft is Bent:
- Symptom 1 is excessive vibrations. Abnormally rigorous vibrations and grinding noise are signs of a bent or broken crankshaft. Look out for excessive vibrations when using your mower that was not there before.
- Symptom 2 are issues with the transmission. A bent or broken crankshaft can hit other parts causing problems in the transmission system. When this happens, your mower will have trouble starting up and running smoothly.
You can also conduct a physical inspection to check for a bent or broken crankshaft in addition to these symptoms. In this regard, you can check the following things:
- If the gap between the crankshaft and other parts is what it should be.
- If the bolt that holds the blade shows any wobbles.
- You can also position a dial indicator on the shaft’s various locations to check if it is bent.
- You can also look for blade wobbling, which could be an indicator of a bent crankshaft.
A bent or broken crankshaft can be very dangerous. If you have determined that there is some issue with the crankshaft, don’t use your mower unless the issue is fixed. The crankshaft rotates at very high RPMs- around 3000 rpm or even more. If the blade rotating at this speed comes off because of a bent crankshaft, it can cut both your feet. So, you cannot be too careful when it comes to crankshaft issues.
Let’s get into the details of known symptoms of a bent crankshaft and the physical inspection methods. After that, we’ll also provide you some information on how a bent crankshaft can be fixed.
Symptoms of a Bent Lawnmower Crankshaft:
There are two common symptoms associated with a bent crankshaft. You don’t need to be an expert mechanic to judge these symptoms. If the crankshaft on your mower is indeed bent, you’ll observe these two symptoms for sure. Just keep your eyes and ears open.
For moving objects, vibrations are inevitable. All moving objects are vibrating at some frequency that is characteristic or specific to that object and an amplitude specific to the motion it is going through. When an object is deformed, or its motion characteristics are changed, its vibration amplitude will change. For example, when the force exerted on a moving object changes, it results in a change in its amplitude of vibration-an increase in force can cause an increase or decrease in the amplitude. An increase in amplitude means that the vibration becomes more rigorous and observable.
Excessive vibrations are the most common symptom associated with a bent crankshaft because of its high rotational speed. The vibrations can be felt for some seconds after intervals of smooth-running, but they are vigorous enough to know that there must be an issue. Excessive vibrations are also accompanied by grinding noise. If you observed these, immediately stop mowing and turn the engine off. Inspect the crankshaft and get it fixed before mowing again.
Transmission problems are also commonly associated with a bent crankshaft. This is because of two reasons. The bent crankshaft can hit other parts messing the ignition system up, or the impact that bent the crankshaft could also break the flywheel and mess the ignition system. In any case, the mower will have trouble starting and will also not run smoothly.
Physical Inspection for a Bent Crankshaft:
You can also conduct a physical examination of the crankshaft to determine if it is in the correct shape or not. A physical exam must be done if you have observed signs associated with a bent crankshaft or as a maintenance routine. Doing a physical exam now and then is recommended because this way, you’ll always stay updated and will know of any issues before they become too serious.
Multiple methods could be used to examine the crankshaft of your lawnmower physically. Some of these methods are listed below.
The Gap between the Crankshaft and the Deck:
In this method, you check if the gap between the crankshaft and the deck changes throughout one complete rotation of the crankshaft. First of all, disconnect the spark plug. The clamp a ruler to the deck using duct tape so that its other edge is touching or almost touching the crankshaft. Then rotate the shaft manually, closely observing the gap between the ruler and the shaft. If the gap changes as you rotate the shaft, it means that it is bent and needs to be fixed.
Remember to wear safety gloves during this procedure to avoid an injury to your hands. Once again, the spark plug should be disconnected when you perform this exam.
Look for Bolt Wobble:
First of all, disconnect the spark plug. Then ask a friend of yours to pull the mower’s starter cord. As they do so, carefully observe the bolt that holds the blade to the crankshaft. Any wobble (sideways motion) of the bolt as the starter cord is pulled indicates that the crankshaft is bent and needs repair.
Use a Dial Indicator:
A dial indicator is an instrument with a dial that measures or detects minimal changes in distance and amplifies them to be visible to the observer. Professionals use dial indicators to measure small displacements in all types of structures, e.g., beams, flat plates, shafts, etc.
You can also use a dial indicator to check if your crankshaft is bent. For this purpose, the dial indicator should be placed at specific points on the crankshaft. The dial’s placement depends on the make and model of the shaft, and you can look for more info in this regard, the manufacturer’s manual or can take help from a professional.
Look for Blade Wobble:
Just like a wobbling bolt, a wobbling blade can also be an indicator of a bent crankshaft. To observe the blade, park your mower on an open flat area and keep the engine running. While the engine runs, carefully observe the blade for wobbling and shaking. Blade wobbling can be caused if the blade is broken, but it can also be an indicator of a bent crankshaft.
Fixing a Bent Shaft:
A couple of techniques are commonly used by professionals for straightening bent crankshafts. These include:
Professionals use shaft straighteners to straighten bent crankshafts. In this method, a mechanical press force is applied at the shaft at the required locations. The shaft may be hot or cold while the force is applied. This is a very efficient technique for straightening the shaft and can make your bent shaft suitable for use once again.
The second method is the use of a sledgehammer to straighten a bent shaft. The difference between this method and using a shaft straightener is that the sledgehammer applied impact force, whereas the straightener applies a pressing force on the shaft.
These methods are not very difficult, and you can perform them yourself at home. Tutorial videos can help in this regard.
Replacing a Bent Shaft:
Sometimes a shaft is too bent and can’t be repaired enough to make it suitable for use. Also, trying to straighten a shaft using the above methods can result in the warranty getting canceled. In any of these cases, you’ll have to replace the bent shaft with a new one. Ensure that the new shaft matches the shaft being replaced and is compliant with your lawnmower engine.
What causes a bent crankshaft?
The blade of your lawnmower rotates at very high rpm. An rpm of around or over 3000 is not uncommon. This means that the blade and crankshaft possess a lot of kinetic energy, which gets dissipated when the mower hits an immovable obstacle. It can result in a bent crankshaft, hitting a hard rock or a tree stump, or a fence.
When your lawnmower hits a hard obstacle when running at high speed, its crankshaft can bend. A bent crankshaft causes many problems, such as excessive vibrations and transmission issues. Furthermore, a bent crankshaft can result in serious injury if you keep using your mower. Using the guidelines mentioned in this article, you can determine if your mower’s crankshaft is bent. Once you determine that it is bent, you must get it fixed or replaced as soon as possible. Remember never to use your mower with a bent crankshaft.
X724/62c. Did I warp the deck or bend the spindle?
I somehow managed to hit a stump yesterday while cutting the grass (I removed it with a maul afterwards) when I was finishing up the yard. After hitting it the mower bogged down heavy and so did the tractors engine until I turned off the pto. It being scorching hot yesterday and about dinner time I decided to come back today and look at it.
First thing I did was check the blades to make sure they were not bent to holy hell. Either way I rotated them it appeared to be tilted lower in the back than the front (looked like about the same amount).
Got the cover off the right spindle and took my little level to check it:
I checked against the center pulley which did not hit a blade (and therefore should be level):
This image is from the opposite side, so the bubble going to the left here should be going to the right in the previous. So, a bit of tilt in the deck but not as much as the right spindle.
I then put the little pulley on the underside of the deck next to the right spindle to see if it was level:
Not a mower engineer, but I reckon the place where the spindle bolts to the deck should be flat relative to the designed cutting plane.
So, do y’all think I bent the spindle or the deck?
Typically mower decks are adjusted so that the front is slightly lower than the rear. They are rarely adjusted to be “level”.
2012 2720.- 200CX Loader.- 54″ Quick Attach Snow Blower.- Frontier LR5060 Rake.- Land Pride RB1660 Blade (Hydraulic Angle).- Artillian 42″ Forks.- Ken’s Bolt on Grab Hooks.- Fit Rite Hydraulic top-link.- 2013 X500/48 for mowing duties.- 2023 X350/42 YUT.
I have a 62c deck and have had problems with the deck being bent at the spindle mounts. One thing you can do is rotate two adjacent blades until they are tip to tip for comparison purposes. You may have to slip the belt to accomplish this. If nothing is bent, you will be able to see that the cutting edges fall in the same plane. Then rotate one of the blades 180 degrees and compare again. Rotate the other blade 180 degrees and compare again. If a spindle or blade is bent, the tip-to-tip comparison will change with the rotation. Do this same exercise with the other blade (left blade center blade, then right blade center blade).
If the deck is bent, the blade tips will be out of alignment on each rotation. I had this problem and was able to straighten the deck.
The spindle mount area is most likely bent. Perform the test as Dirtdobber explained. You’ll need to remove the deck and flip it over to correctly check it and to to repair it. I’ve repair some in the past by placing the deck onto wooden blocks, one on each end of the deck and a couple on each side of the bent spindle area. You’ll need to “strike” the deck using a block of wood and a heavy hammer(8Lb. or 10Lb. maul).
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