It’s easier to do a better job sharpening a blade off the machine, but first you’ll have to know how to remove a riding lawn mower blade.
It’s certainly possible to sharpen a blade while it’s on the machine. I believe that you can do a better job when it’s off the machine, and I recommend that – especially for beginners.
When it’s on the machine, you’re limited with access. You have to lift the machine off the ground to get at the blade, and usually that leads to an uncomfortable position.
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By removing the blade, you don’t have to worry about access. Furthermore, you can clearly see the bevel for sharpening.
You want to remove as little material as possible when sharpening the blade to prolong the life of it. This means to keep the same bevel, or angle of the blade.
If you’ve got some serious nicks in the blade, it will obviously take more work, and you’ll have to remove more material. But the goal remains the same.
Which leads us to the all important question:
How to Remove a Riding Lawn Mower Blade
The blade is held onto the mower deck by a bolt into the spindle. The spindle has internal bearings and a pulley on the top side.
Now, if you throw a ratchet onto the bottom bolt to remove the blade, it’s just going to spin the pulley.
These bolts are notorious for seizing due to the wet conditions they work in. That alone makes it difficult to remove, but when you can’t grab anything on the top side, the pulley usually just ends up slipping.
There are two solutions to this problem. Maybe three.
First, you can use a strap wrench to grab onto the pulley. If you can get a good bite on it, then perhaps you can spin the blade bolt off the bottom of the spindle.
The next option is to remove the deck from the machine, use a puller to remove the pulley, and then use a vise grip to hold the shaft while you attempt to remove the spindle bolt.
I don’t recommend this because it’s highly likely that you’ll mar the surface of the spindle shaft with the jaws of the vice grip.
I have seen online where people will coat the jaws of the vice grip with hot glue, but I still kind of doubt that it will fully prevent damage.
The best, and simplest option is to use an impact gun.
Because it delivers impact (duh!) it can shock the bolt out before the spindle has an opportunity to spin.
In most cases, this will work as is. If you still have a difficult time removing the blade bolt, remember to apply lubricating oil liberally and consider heating around the bolt.
Once the blade is off the machine, go ahead and throw it in the vice and sharpen it according to your preferences.
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