Which Way Do Mulching Blades Go On? Complete Installation Guide

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If you buy a lawnmower blade or want to sharpen your old blade, you might come across the challenge of installing a lawnmower blade. There is a fifty-fifty chance of getting it installed wrong or right.

Installing it wrong can structurally damage your lawnmower and the lawn itself. It causes poor cutting, uneven growth, and uprooting of the grass of your property.

So when you install your blade, one question pops up in mind:

“which side of the lawnmower blade is up?”

Either it is mulching or a standard blade, If you have put it the wrong way, you will be cutting nothing with the backside of the blade, which is the dull side and not sharp to cut the grass.

And

If you put it the right way, that will put a smile on your face when you are done mowing.

Here are the complete details on this:

Which Way Does a Mulching Blade Go On? Check By Different Methods

To understand the right side of the mulching blade and which way it should be fit, you can opt for the following methods.

Design or Shape

There is bent in the shape or design of the mulching blade. If you observe, the middle part of the blade is flat, and it gradually curves up to the edges.

That flat part should be mount on your lawnmower in a way that the curve parts having cutting edges face down when your mower is standing in a normal position.

Metal Flaps / Bevels / Teeth-edges

It would be best if you also look for the metal flaps of the blades. I personally use and prefer this method.

Metal flaps are parts of blades that are interchangeably called edges or wings, or bevels. These parts have a sharpened edge and serrated teeth in some mulching blades.

The metal flaps or teeth-edges or bevel should be up, and cutting edges should face the ground when you put a mulching blade on.

Stamp Number, Model Number, Sticker or Etched Words

In comparison, this method is way better to detect which way a mulching blade goes on. 

You need to look for stickers, stamp numbers, model numbers, or etched words mentioned on the mower. You can also look for the words like “This side down”, “bottom”, “toward grass”, etc. 

Not to mention, these are present only on the one-sided middle section of the blade.

Additionally, Stamp numbers, stickers, model numbers, or etched words should face the bottom or ground when your lawnmower is upright.

Cutting Edge

Cutting edges is another way to ensure a good mulching blade installation.

You can put your thumb against the edge to check it’s the cutting one, and this should face the ground as this part ensures good grass cutting.

Also, the cutting edge can be dull or shinny in color, which gives the idea that the shinny part of the metal is the sharp one, and it should be facing the ground after you install your lawnmower blade.

Get an Idea From the Old Blade

It’s better to make a video or pictures while removing your old blade. This way, you will understand how to mount it properly step by step.

Check By Wobble Test

Wobble test is used to check if you mount your blade on mower and it is loosened or shaking instead of firm fitting, then you should know the blade fitting is not right, and you have used the wrong side.

Reversing the side will resolve to make the proper installation in that case.

You can perform a wobble test by shaking the blade to check the fitting. It is recommended to use reducing washers and right bolts for a good fitting of mulching blades.

Mower Type

The mower type is another important entity to mention here.

Two types are noticeable here:

Reel mowers (cylindrical nature): These mowers don’t require checking for the side of the blade before you install it, as they can rotate the blade on both sides and cut evenly. You can use your manual if they serve this function.

Mulching mower: mulching mower has clockwise assembly so cutting, edges must face in the direction of rotation.

Check Manual

Manual is the right way to learn by reading because it has clear instructions on replacing or mounting a mulching lawnmower blade. 

Moving Direction of Crank Shaft

Check the direction of rotation of the shaft of the mower. The Crank Shaft is the part where you mount your blade.

The best way to check is that turn off your mower and pull the “Starter Pull Cord” to some extent to observe the movement of the shaft, which is mostly clockwise, so the cutting edge should be in the direction of the way the shaft moves.

You can also check the rotational movement from the discharge chute, which is on the right side of the deck of your mower, then the shaft will move clockwise, and so will the blade.

Summary

On final thoughts, any method you choose from the above list, the right way to go on is to fit the mulching blade such that the cutting edge should face the ground or installed downward and flaps or teeth edge is upward or towards the deck after fitting.

How to Install Mulching Blades? Complete Steps

Before you do the installation, always check the compatibility of the mulching blade with the mower. After ensuring it is the right fit, you can go with the installation.

I have explained the installation procedure here.

Following this procedure will help you install mulching blades on Craftsman, Husqvarna, John Deere, and other mowers. It will prevent grass stripes when you mow as lawnmowers leave stripes of grass when the blade fitting isn’t right.

Material Required

  • Leather gloves
  • Wrench
  • 2 x 4 Wooden block
  • Reducing washers

Steps to Follow

  • Drain out the fuel to prevent spill, or if your mower is on gas, siphon it out.
  • Place the lawnmower at some high place where you can see the bottom part of the mower.
  • Or you can simply lay it down on one side if it is of a small deck. Before you lay it down, make sure the air filter is up to prevent the oil from saturating the filter.
  • Disconnect the spark plug wire, keep carburettor and filter assembly high to prevent oil leakage into the carburettor.
  • Place a 2 x 4 inch wooden block in the deck so the old blade cannot move and remove the old blade from the shaft by removing the reducing washers and nuts.

“Here you can make videos or pictures so you can remember how to fit the new blade in

  • Identify the right side of the blade from the sharp edges or the other parameters I have mentioned earlier. Those flaps or curved edges should face towards the deck or upward position.
  • Now put the hole of blade on the mounting shaft and use a wooden box to prevent blade movement.
  • Place washers, nuts and tighten it to 80 ft pounds torque firmly with a wrench, so it doesn’t wobble.
  • Remove the wooden block and plug in the wire.
  • It’s a good practice to clean your deck and use silicon spray to prevent the built-up clippings from compromising the airflow.
  • Close the discharge chute after fitting as mulching blades cuts by making a vacuum under the deck, which is built only if the discharge chute is closed.
  • Run your mower on a smooth lawn to check it is working right.

Precautions

  • Always wear gloves to avoid damage to the hand because blades are sharp.
  • Always unplug the spark wire or turn off the mower completely. If you are using a battery-operated mower, remove the battery first, so it may not accidentally run on you or damage by moving the blade.
  • Keep the mower at a place where it doesn’t shake when you are tightening the blade.

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Jack

After doing my master’s in agriculture, I went on with this field for more than 15 years because I love working in green. I have experienced using modern machinery and techniques that can help farmers and landscapers to achieve something great. My goal will be to deliver you the best reviews and information to make the right decision.

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