Hack a Mower to Build Your Own Red Neck Trimmer Mower




A Trimmer mower is similar to a regular mower but is much better for cutting tall weeds.  A regular mower just runs over them, pushing them down and out of the way of the blades.  whereas a Trimmer mower because it doesn't have a front cuts them down.

A trimmer mower also produces less dust helping people with bad allergies to grass (Like my wife).

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Step 1: Buy an After Market Trimmer Head and Install It.

You can buy a number of replacement trimmer heads from Home Depot, Lowe's, or your Local Hardware Store.

Look for one that DOESN'T spool out more line as needed (you may be able to get this to work, but I don't know.).  And attaches to the trimmer with a bolt.  It should also have a very round bottom, unlike a whacker this trimmer head needs to be able to support weight and glide across the ground.

I purchased and used this one.  

Remove the blade from the mower, and see if the bolt head will fit through the trimmer head.  If the head is too big (mine was) you need to grind off a little material from each edge of the bolt head so that it will fit.

With that done, simply screw the trimmer head on.  

Balance is extremely important, so if you install longer trimmer lines, make sure they are the exact same length.

Step 2: Drain the Fuel Tank or Remove the Engine From the Mower Deck

At this point you'll want to drain the fuel tank or better yet remove the engine from the deck.  I cut mine with the tank full, but with a wet t-shirt completely surrounding it and the carb.  But I just barely nicked it with the cut off wheel.  Fortunatly there was no fire.  (See the picture of the cut in the tank with gas pouring out of it.)

Step 3: Cut the Front Off the Mower.

This doesn't really need to be precise.  Be sure you leave enough metal that the mower is still fairly strong.

I used a cut off wheel for as much as I could but there where a few place I couldn't quite reach.  I would recommend just removing the engine.  It will make it MUCH easier.

For the places I couldn't reach with the cut off wheel I sharpened an old flat face screwdriver so it was like a small chisel and used it like a can opener to cut the deck.  (The deck on my mower was very thin).

Step 4: What I Would Do Differently Next Time.

I would definitely remove the motor before starting.

The mower will be fairly flimsy when done.  When I get time, I'm going to put some 1/4" steel rod around the outside edge where the deck was cut, and add a few stiffening supports.  

I also want to put some longer string in it.

A real trimmer mower has larger wheels that are placed directly under the engine, this makes the weight balance nicer and keeps more weight off of the trimmer head.

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    19 Discussions


    3 years ago

    I mistakenly went to youtube first, I should've known it would be on instructables first :). I think will do this with an old honda mower frame with all the self propel stuff ripped out. then I can put the handle on the other side so the weight isn't all on the front. A pressure washer engine would be better fitted since the shafts are so much shorter in general too. Great thinking for the function and fit, do you plan on making it tidy and seemless or just getting the job done?

    1 reply

    Reply 3 years ago

    Actually, I ended up scrapping it. It worked, it worked pretty good, but, I live in a small community, and without a guard it flung debris everywhere. Also, the motor really needed the extra rotational mass of the blade to make it work right. I don't think all lawn mower engines need a blade on to run properly, but this one would backfire sometimes when you were starting it, which would rip the starter cord out of your hand (not fun). But, it worked, it did what I needed, and I learned a lot from it, so it was definitely a success.


    5 years ago on Introduction

    Thank you for easy to understand instructions plus pictures. If I put it on the proper side and was able to change my blade without any more interruption! This article is very useful for maintain a lawn mower.

    This is rad. Look around for Jet-Fit heads. They take line that is about 3x as thick as the walmart variety stuff. Just jam 2 pieces in the ratchets and go, if you pre-cut the lines with rabbit-clippers or lineman dikes. .130 line will work for grass and some weeds. .155 works on almost everything. ".155" flexiblade will beat down woody weeds 1" thick! The 2 string head is about $25

    2 replies

    I guess I got a good deal. Here's one for $45. http://www.ereplacementparts.com/2line-jetfit-express-trimmer-head-p-269713.html

    Here's one for $35 shipped no tax. http://compare.ebay.com/like/390556267334?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar

    People talking about cutting off their toes are silly. You don't leave it running when you stop mowing. Let go of the bailing bar and it brakes the flywheel and shorts the spark. Walking behind it is just like a regular mower, and the strings are safer than a blade. If you leave a little more of the deck when cutting off the wheel mounts, it will throw less stuff.

    yes they are that is why a mower setup as a trimmer has a larger pulley on the back with a belt going to a smaller pulley setup. This also stabilizes the engine as you need a counterbalance or the engine will shake itself to death.

    The one I have (yard machines MTD) has a large flywheel on the mower shaft, but a small pulley on the engine output shaft, feeding a larger (reduction) pulley on the trimmer head shaft.) So the engine is actually running faster than the trimmer head.


    Reply 7 years ago on Introduction

    I wasn't sure about that either and thought they did. But it worked great. It may be the head has stiffer line in it then a regular head so it works at lower rpm.

    Yard Sale Dale

    6 years ago on Step 4

    Hi. Have you mowed some stuff with it yet? I was thinking of making one like yours, with an old high wheel mower (the kind with 2 big wheels in back).

    I used to have a 6.5 hp Intek on a push mower deck, with an Echo fixed head. The mower just idled the whole time and would cut down alleys and stuff. People worrying about the speed should relax. Even the 3.5 can do it, and 3000-7000 rpm is plenty. The wheeled trimmer (factory made) I have has a reduction pulley drive, and basically just runs mid-throttle all day. The string head has a steel dome on the bottom, and the engine has a flywheel. It's great, but it's fun making stuff too. Good luck with more mower builds.

    1 reply

    Hi Dale,

    I have mowed with it. I stopped, because I live in a neighborhood, and the trimmer throws stuff everywhere... But, if there isn't anything fragile around, it works GREAT!

    Yard Sale Dale

    6 years ago on Step 3

    I used a sawzall on one I made today, and it worked great. I used a cut-off torch on the last one and it worked fine but was slow and made a lot of sparks and mess, and required removing the engine. Cut off wheels are harder to use. Cool build though.

    Good job. I made something somewhat similar. Which head did you use on yours? That looks pretty good. I bet yours works great. Some people are just complainers and naysayers. Don't worry about them. They probably never even mowed.


    7 years ago on Step 2

    Next time take the four bolts out and remove the motor from the frame, will make it easier and safer to cut.