How do I sharpen my lawn mower blade? Getting prepared – Part 1 of 3.

Keeping your lawn mower blade sharp is important to both your lawn mower and your lawn. Those of you who sharpen your own lawn mower blade have 2 options – sharpen the blade while it is on the mower or remove the blade and sharpen it off the mower. In this blog post, I will go through the detailed steps needed to prepare to sharpen your mower blade – either “on” or “off” your lawn mower.

Albeit much faster to sharpen the blade on the mower, removing the blade allows you to do a much better job at sharpening the blade and making sure it is balanced. Regardless of which way you wish to sharpen your blade, there are a few things you need to pay close attention to before you start.

First – safety. Make sure the mower engine start control is set in the “off” position and the spark plug wire is taken off of the spark plug and grounded to the engine. Failing to do this might allow the engine to try and start while you are trying to sharpen the blade or while you are trying to remove it from your lawn mower. This can result in possible bodily injury and damage to your lawn mower. A simple tool called a “Piston Locking Screw” *requires that you remove the engine spark plug so that this tool can be installed. There is now no way your engine can start while you are working on it. Also, this tool prevents your engine crankshaft from turning which makes it much easier for you to remove the blade or sharpen the blade while on the mower.


Using this tool, there will be no no chance of the engine possibly starting, you can now safely work on your lawn mower. If you have a fuel shut-off valve, turn it so that the fuel flow is off and tip your mower on its side with the carburetor side being up. This will help prevent fuel leaking into your engine and flooding it.

Next, and very important, take a close visual inspection of the blade, blade mount, and all blade retaining bolts. Is anything loose, broken or damaged? Is one side of the mower blade bent differently from the other side? Are there large deep “dings” in the blade edges (more than 4mm)? If you find any of the above issues, then you should take your lawn mower to be serviced by a trained technician. If not, then you are now ready to sharpen your lawn mower blade.

Stay tuned for my next 2 blog posts where I go into detail on how to sharpen your lawn mower blade “on” or “off” your lawn mower!

Work safe!

*  For engines where the spark plug is located directly above the engine piston.

Why do I need shear pins – can’t I just use a regular bolt in my snow blower?

Yikes! Never use a regular bolt to replace a “shear pin” bolt!

Some shear pin bolts look a lot like regular bolts while others look similar but with “relief” cuts recessed in their shanks or are fitted with special spacer collars.


The main fundamental difference in the design of a shear pin bolt to that of a regular bolt is that a shear pin bolt is design to fail. That’s right! As weird as that may sound, shear pin bolts are designed to fail (shear off) at a specific level of shearing (sideways) force. It is with the failure of the shear pin bolt that potential damage is not extended to your snow blower drive train system. The shearing of the shear pin bolt releases all force off the snow auger allowing it to no longer be driven but to spin freely. The blower drive train still continues to spin but with a sheared pin the snow auger no longer turns. The brass driven gear is damaged because the use of a regular bolt allowed the full force of a stuck snow auger (caused by a rock that got caught between the auger and the lower snow scraper bar) to transfer back to the brass driven gear causing gear tooth breakage and other damage. Unfortunately I have had to replace a few expensive brass driven gears that were damaged beyond repair because the owner used a bolt instead of a shear pin!



Using the correct shear pin bolt will only cost you a few dollars but this little special bolt was designed to save you having to spend much more on repairs!

Welcome to Cutter’s Choice BLOG site!

Hello, My name is Andy Bethel and on behalf of the Cutter’s Choice team I would like to welcome you to our blog site. We will strive to provide Woodcutters, Arborists, Landscapers, and even the Do-It-Yourselfers with current and relative information to assist you in this most amazing industry!