Electric Lawn Mower

Introduction

I have a small lawn in front of my house, which is a rarity in Indian houses. Ranaghat, where I live, is a suburban town in the state of West Bengal in Eastern India. I needed a lawn mower, and found that it would cost me around Rs.5000 (USD 120) to get one from the city. Hence I took recourse of some available machines and material at home and came up with a neat little design of an electric lawn-mower.The cost of the project was slightly less than Rs 1000 (USD 23), much less than what I would have had to spend to buy one.

Step 1: The Blade

The blade is a rectangular piece of iron. I got it cut out of an old hand saw (used by carpenters) that I had, and sharpened the edges at a workshop, and bored a hole in its centre. Through this will pass a bolt.

Step 2: The Iron Framework

Here is a disassembly of the iron framework. I got a blacksmith (in India, the best place to do it is at a place where they make window grills) to bend 6 iron rods to these shapes, And join the pieces together using nuts and bolts as shown. I did not have to work out the dimensions, but gave them a picture just like this one and they shaped the rods and aligned the holes. Do use washers at every joint, which I haven't shown in the diagram for brevity. The photos and videos will give you a rough idea about the size.

Step 3: The Drill-holder

This is the holder for the drill. It's drawn in a separate picture here. This too I made at the blacksmith's. They have enough junk lying around in their workshops to make one of these. The semicircular strips of iron were welded onto the heads of the two very long bolts. The reason I used such long bolts is that I needed the threading on their surface. These rod-like bolts will eventually have nuts screwed onto them from two ends, placing the drill-holder contraption in its place in the metal framework. The body of the electric drill will pass through the circular opening and will be clamped by nuts and bolts.

Step 4: Attaching the Drill-holder

Now, the interesting part. As you've seen before, this drill assembly is clamped horizontally, right in front of the framework. Take a carefull look at the assembly. The two vertical rods in front have channels running along their lengths.(This was made by using two square iron bars placed parallely and joined at the ends with small pieces of similar square iron bars of the same length as the speration between the parallel bars.) The ends of the drill-holder will pass through them and are tightened from each end by nuts.( Remember that the drill-holder's rods are bolts with threading on them). This could have been achieved by keeping holes in the vertical rods, as there are, at all the other joints of the framework. The purpose of the channel is to give us a facility to vary the height of the blade from the ground, by moving the drill-holder up and down before clamping it to a fixed position.

Step 5: Wheels

These are simple wooden disks with holes at their centre. These holes are big enough to hammer a ball-bearing through them. Ask the carpenter to make the holes slightly smaller than the outer diameter of the ball bearings. You'll need 3 such wooden disks, and hence 3 ball bearings.

Step 6: The Electric Drill

This is the lawn mower's engine. Buy any simple electric drill with a long cord that'll lead to a plug point. The drill should be a small one, that'll consume minimum power and will be light. Because cutting grass hardly requires any effort and the iron framework should be able to support the drill. My drill I bought for Rs. 700 (USD 16) and its power consumption is 250 Watts.

Step 7: Assembling

The machine is composed of the above parts.

In this short paragraph I'll explain how they fit together to make the lawn mower. So before assembling them you should have all this ready:

The blade
A thick bolt, a nut and washer to fit the bolt.
At least 9 sets of nuts-bolts-washers.
The 6 iron rods
The two halves of the holder for the drill
3 wooden wheels
3 ball-bearings
An electric drill

Assembling

Hammer the ball bearings into the holes on the wooden wheels.
Put together the assembly, joining the pieces by nuts, bolts and washers. This process puts the wheels in place too. Do use washers on both sides of the wheels so that the wooden surfaces of the disks do not rub against the iron rods which hold them in place. Only the washers and the heads of the bolts will make contact with the thick rim of the ball-bearings.

Once this is in place, screw into place the two halves of the drill-holder into the vertical channels. Don't tighten them right now. Place the drill, head down, in the circular space and clamp it tightly in place.

Pass the large bolt through the hole in the blade and tigthen it with a nut and washer. The remaining length of the screw will be held between the three teeth of the drill. So, in place of the drill needle you now have a T-shaped structure, that'll rotate like a propeller when the drill is switched on.

Step 8: Using the Lawn-mower

Now that the lawn mower is in place, take it to your lawn and adjust the height of the blade from the ground by moving the drill-holder along the channel. When done, tighten the nuts at the ends of the drill-holder. Connect the drill's wire to a plug-point nearby, switch it on.

One thing I haven't described is how to manoeuvre the mower. Well, the best bet is to attach a rope to the horizontal rod (just above and running parallel to the drill-holder), and pull it by the rope. I wouldn't recommend dragging it in circular paths too much,as this would generate twisting forces on the framework and especially the wheels and loosen the joints. But, of course, you can experiment and improve the design further and make it tougher.

See the attached videos :

1. Clamping the drill
2. Attaching the blade
3. Running the drill
4. On grass

Comments

[Cross_]

Assembling this was cheaper than buying lawn mower? Trying to get the raw materials and have somebody cut them to size would be way more expensive here than buying the factory made item.

[simonrafferty]

I think this is brilliant!  No more complicated than it needs to be.
As for adding guards - I'm a believer in 'risk compensation'  If it looks like it will mangle your toes and kill you - you'll be more careful with it than if it looks all cuddly and safe.  As a result, making a dangerous thing look safe may in fact make it more dangerous!
Imagine how carefully you'd drive your car if there was a big spike sticking out of the steering wheel!

[dbenedetto]

WELL SAID!!! These whiney wusses complaining about safety. Only in america.

[RiddlywalkerB]

yeah right... if this tips back the blade will dig into the ground and throw the machine sideways... I use pretty wild home made stuff in my workshop, but at 20, having been to the ER with my friends thumb and forefinger in my pocket (he thought he was still attached to them after his 'experiment') I try to create devices that won't involve painful operations, ambulances, and permanent changes to my working life.... good luck, wear those safety glasses!

[t.rohner]

I can only second your comment.

In my younger days, i laughed at the regulation crazyness in the U.S. But it seems, that it only takes some 10 years more, until it reaches lil Europe. (I live in the middle of it, without beeing in the EC) I was actually researching to build a autonomous mower. Maybe start out with a RC-controlled type and then upgrading it with a cool software.

[simonrafferty]

When I was about 15, I 'modified' my Dad's lawn mower to mow by itself. It was a lot simpler than RC. Just one motor which drove the wheels and another driving four cams, two at either end. I had a pair of rollers one in front and one behind the mower. When a roller dropped off the edge of the grass, it stopped the wheels then turned the turned the cams a few revolution. Each revolution, the cams lift the mower and move it sideways a few inches. The drive motor then reverses and runs until it repeats the sequence on the other side. It had no intelligence, just a couple of timers and did an OK job!

Unfortunately my dad didn't really see it as the cool thing I saw - more me tinkering with HIS mower! He (in a somewhat angry manor) suggested that the junk be removed as he enjoyed mowing the lawn! Now somewhat older than he was then - I can see the cathartic nature of mowing and would probably be similarly displeased! (though - as a die hard techie, I doubt I could stop myself smiling and helping to 'improve' it!). Dad was no Techie!

The Cams were driven by an car electric window motor & box IIRC - and the drive from a kids electric ride on tractor which I procured from somewhere!

[bremus]

This has to be one of the most dangerous and incomplete instructables ever.

[Matt428]

Well said...

[JanPieterman]

Your next instructable is prbably NOT a step by step manual?
Cause: missing a limb?
But I liked the simplicity of your mower though.
Great work.

[russ_hensel]

Just a note to let you know I have added this to the collection: Cordless Drills Hacking for Other Uses !

>> https://www.instructables.com/id/Cordless-Drills-Hacking-for-Other-Uses/

Take a look at a bunch of project involving odd uses of drills.

and for even more drill info

>> https://www.instructables.com/id/Cordless-Drills-A-Collection-of-Collections/

[Datawolf]

A friend of mine broke a window while mowing.
Can you imagine how your mower is DANGEROUS ?

[germeten]

You could use a wooden hub in the drill with bits of cable, for a blade, much safer. The front wheel could be on a caster, for better maneuverability. I admire your creative audacity.

[jbaker22]

You will get a lot better reviews if you go to a junk yard or lawn mower repair shop and put it on the body of a broken mower. $10 bucks can save a limb and make you more popular.:)

[robbtoberfest]

I love it. Does it actually cut grass? I would think the RPM and torque wouldn't be high enough.

[susanta]

Well, I really did not get down to mechanical power of the system and specifics such as torque and RPM when designing it. But it works fine for my lawn , yes it does cut grass :-)

[unpro]

I tried this, took an aluminium ruler, drilled hole and sharpen it up. Tried to POC on my el-cheapo drill (rated 3000rpm, but I thin it's a lot slower than that) Vibrates like crazy (maybe hole not centered) Doesn't cut anything. Sharpen aluminium ruler cuts my finger, fruits and what not. I noticed standard comercial grass trimmer do about 5k rpm, how fast does your drill spins?

[kiwiman64]

Oh man that is ghetto! Very cool dude.

[tchang2010]

can it actually cut the grass? i feel like the drill is not fast enough to make the cut.

[rhoula]

That was extremely funny man. I couldn't stop laughing. But over all its a great Instructable.

[twhaley]

This instructable has changed my life, thank you.