Easiest Way to Install a Brush Blade on Your String Trimmer
Welcome back to Main Street Mower! Today, we're going to cover a quick but important upgrade for your string trimmer—how to remove the plastic bump head and install a metal brush blade. If you're looking to tackle thicker grass, weeds, and even brush, switching to a metal blade can make a world of difference.
This guide will walk you through the process step-by-step so you can get back to work in no time.
Removing the Bump Head
First things first, you need to take off the bump head from your trimmer. To do this, you'll need either the specialized tool that came with your trimmer or a simple flathead screwdriver. Locate the small hole on the trimmer’s head, then insert your tool into it. This locks the head into place so it doesn’t spin while you work.
Now, remember this: the bump head is typically secured with a left-hand thread. That means you turn it to the right—clockwise—to loosen it. If you’re familiar with the phrase “righty-tighty, lefty-loosey,” this is the opposite. Once it's loose, go ahead and remove the head.
At this point, you'll see a stud where your bump head was attached. Take note of the small raised collar near the gear head; this will come into play when we mount the new blade.
Choosing the Right Blade
Not all blades are created equal, so let's talk about the different kinds of blades you might be switching to. There are two main types:
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Multi-Directional Blades
- These blades are versatile and can be mounted in either direction. Whether you're cutting at an angle or straight into thick vegetation, these blades will get the job done.
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Directional Blades
- These need to be mounted in a specific direction because they're designed for specific tasks. For example, some wooden brush-cutting blades or scratcher blades need to spin the correct way to work efficiently.
Generally, if the blade has a logo like STIHL, you’ll want to be able to read it when looking at the machine in its upright position. This way, you know it's facing the correct direction.
Installing the Blade
With the bump head removed and your preferred blade selected, you’re now ready to mount it.
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Mount the Blade: Place the blade onto the stud, making sure it sits correctly onto that small collar we talked about earlier. This collar helps center the blade, ensuring smooth operation.
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Add the Splined Washer: Next, you'll place the splined washer on top of the blade. You’ll feel it “click” into place—this washer is designed to grip the blade and prevent any slippage during use.
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Secure the Nut: Now, add the protective nut. Like the bump head, this nut is also left-handed, so you're going to need to spin it to the right to tighten. The goal here is to protect the threads on the stud. Once it's in place, grab your STIHL Scrench (a combination screwdriver/wrench) and tighten it all up.
Common Installation Issues
Be careful throughout this installation process. If the blade slips off the collar or isn't seated correctly on the gear head, your trimmer will vibrate heavily when you turn it on. This is a dead giveaway that something's wrong. In that case, stop, take everything apart, and remount the blade.
Once everything is properly seated, the trimmer should run smoothly. If it feels off, don’t push it—double-check the settings and try again.
Getting Ready for Brush Cutting
Now that you’ve got your blade installed, you're all set to take on those tougher jobs. Whether it’s thick grass, pesky weeds, or even some brush, your string trimmer is now equipped to handle it. Remember, having the right blade in place not only makes your machine more effective but also safer to use.
Products Used in This Tutorial:
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STIHL FS 131 R Gas Powered String Trimmer
(A heavy-duty trimmer perfect for both commercial use and hefty DIY jobs.) -
STIHL Grasscut Blade
(Choose the appropriate blade based on your needs—8 teeth for mowing thick, dry grass or reeds.)
If you’re interested in learning more about which blade is best for specific tasks, make sure to check out our full review video exploring the best brush cut blades on the market here.
Final Thoughts
Switching from a plastic bump head to a metal blade can transform your string trimmer into a powerful brush cutter. With just a few tools and a little know-how, you'll be able to expand your trimmer's capabilities and tackle more demanding jobs.
Ready for your next task? Grab the right blade, follow this guide, and you'll be cutting through heavy brush like it's nothing.
For more gear or advice, don’t forget to browse our wide selection of STIHL string trimmers and accessories on our website. And if you're looking for more tutorial videos, subscribe to our YouTube channel or watch related videos in our Best Trimmers, Lines & Blades Playlist.
Stay sharp, and happy trimming!
Products Discussed In The Video
- STIHL FS 131 R Gas Powered String Trimmer
- Grasscut Blade - 4001 713 3801
- Steel blade with 8 teeth. For mowing thick dry grass and reeds
- https://www.mainstreetmower.com/products/stihl-grass-cutting-blade-4t-8t?_pos=1&_sid=927e0ab29&_ss=r&variant=43721046032633
Check out more fun and informative videos on our YouTube Channel here:
https://www.youtube.com/@mainstreetmower
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