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How To Sharpen A Reel Mower

Some of the common questions about a reel mower, also known as a manual push mower, include “Do I need to sharpen my reel mower?” or “Can I sharpen my reel mower myself?”. These are just the two out of dozens; differently phrased but meaning the same. The answer? Yes, definitely. Over time, the blades of a reel mower tend to dull out, like any other blade you use. As you trim your grass, little debris like rocks, pebbles, twigs, etc. fly in and contact the blades, rendering it blunt the more you use it. Therefore it is very important ​to sharpen your mower blades regularly to maintain its longevity and to get the best results every time.

​The basic structure of a reel mower includes two primary wheels on a single axle with either a bar of rollers or a set of smaller, secondary wheels in the rear. The function of the rear roller or wheels is to provide balance, while the primary wheels provide the movement required to turn the mower's bladed cylinder. The pushing force results in the axle turning, which in turn spins a pair of gears. One of the gears has a larger diameter than the other, which transfers its torque to the smaller one and by doing so, the torque increases. There is a brush bar on the front of the mower which bends over tall grass into the spinning cylinder blades. The grass is cut as the spinning edges greet the stationary cutter bar, located in the rear of the mower; just like the point of contact between the two blades of scissors. ​And the role of cylinder is to scoop up the grass and move it to the cutter bar, just like the role of a comb to place the hair for snipping. As all these things are happening, the flying debris (mentioned above) can make their way ​and hit the blades due the mower wheel running over them or due to resultant air in that region.

There is more than one way to sharpen the blades. Go through the following steps and choose either method you like.

1) Safety

Ensure that the reel is secure, and not spins accidentally, by inserting a broom or some sort of bar perpendicularly through the mower’s blades. Keep your hands away from the cutting edge. Wear comfortable clothes with no dangling bits and no ornaments. Wear closed shoes or boots to prevent injury and safety glasses/face shield to be safe from particles flying into your eyes or face.

2) Sharpening with a file

Before sharpening, ALWAYS cleaning the blade. It can be done using a wire brush or rough sandpaper. Once cleaned, place the clean blade on a flat surface with the cutting edge overhanging a bit out of your worktop. Then use the file to scratch through the edge of the blade, making sure you go forward and backward along the entire length of the blade. Repeat filing multiple times on the same spot, for the entire the blade, until you desired sharpness is achieved. Do the same thing for the back of the blade as well. You can do it as shown in the picture also. As reel mowers come with varying sizes and numbers of blades; this sharpening process will have to be done on all of them.

Once you are done with the sharpening, it’s time for greasing to prevent rusting. You can either spray a lubricant on the blade or pour some lubricant on a piece of cloth and wipe down the blades with the grease-soaked cloth.

Watch a demo here:

3) Sharpening using a back-lapping kit

Lapping is a process in which two surfaces are rubbed ​against each other with an abrasive between them. Using back-lapping sharpening kit is another simple and effective way to sharpen the blades. The kits come with a handle and the sharpening/lapping compound. Sharpening compounds are mainly grainy substances suspended in a thick, gooey paste, which sharpens the blades when they rub against a surface. The reason for them to come in this paste form is to prevent these micro-granules flying about in all directions as you start lapping.

To begin the process, adjust your blades so that they are touching the bed knife equally, across the whole width of a blade. If a blade is bent severely causing it to hang up on the bed, try tapping it lightly with a hammer or twisting it with a pair of pliers, but only if it is absolutely necessary. ​After this is done, spinning the blades now should be making a scraping noise, which is exactly what to look for.

Then, using a small brush, apply some of the lapping compound on the edge of the blades and start cranking the driving gear backwards using the handle that came along. Do it for some time and reapply the paste to repeat the process. Do this until you start seeing a shiny surface on the blade where the compound ought to scuff away the surface, resulting in a sharp edge matching the knife bed. By this time, as the blades get more and more refined, the scraping sound should also go away. If you feel the process is straining your hands, you can use a power drill to rotate the blades backward. It should be done backwards so that the cutting edges never meet.

After doing this part, clean off the compound as much as you can and check the blades to see if you have missed a spot. If there is any, apply some more compound on those parts and repeat until you are satisfied. Test the sharpening by using a piece of paper. By this time it should be cutting like scissors. If not, try adjusting the knife bed. Lastly, clean and grease the mower for full efficiency. And you are done!

See this video to fully understand the process:

How To Adjust A Reel Mower

Faulty blade contact can impede the efficiency of your mower, making you think it’s time to sharpen, when actually all it requires is a simple adjustment. First, place your reel mower on a workbench and block its wheels from moving, using a wedge. Then, using your hand, spin the reel to decide what kind of adjustment is needed. If there is a scraping sound, the blades and the knife bed are too close; you should adjust the blades away from the bed knife, except for the time when you are about to back-lap. If the reel spins too loosely, the distance is too much; the blades should be adjusted closer to the horizontal cutting bar.

After deciding, put a flat-head screwdriver into the screw slots located on the side of the reel. To move the blades closer, tighten the screws. And to move away, loosen. Make very short turns, only a fraction at most, to avoid over-doing the adjustments.

Next, turn the screws on each side of the cutting bar, but in the opposite direction of reel screws. Again, use minimal adjustments. Check your work by spinning the reel and at this point if you need more adjustment, continue the process until the reel’s blades operate satisfactorily.

D​id you find this article useful? How do you ​usually sharpen ​your mower blades?  Let us know in the comments!

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The Best Manual Push Mower - 2019 - November 8, 2019

[…] you wear gloves to avoid any accidental scrapes on sharpened blades. Check out our article about sharpening reel mower blades to learn […]

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