Electric rototiller conversion
 

My father in law had this old engineless tiller in the trees and I had an old 3/4 hp 3500 rpm electric motor so I thought I'd see if it would do the job. Just used the on/off switch on the motor and engage the tines with the clutch. Took about an hour and a half to build and seems to work quite well! Surprised how much less hp you can used with electric...

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Almost there

Here we go...
http://i245.photobucket.com/albums/g...psa3335a0e.jpg
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Nice project.

Maybe take a short video I would love to see it in action.

Nice conversion! I bet its a lot quieter than it originally was too.

I recently mowed my grandparent's lawn with their gas riding mower. My first thought was 'wow, its loud'. :) I'm used to my battery electric riding mower.

So you are tilling with a cord behind you?
Did you do a chain or belt drive off the motor?

Ya behind. it's a belt, the tensioner is the clutch

Is that a bench grinder motor that you used? I have seen people rig them up to roto-tillers and lawnmowers before. My one buddy left a grinding wheel on the other end to act as a flywheel, it worked awesome.

Another smallish motor that works well is that from an old electric edger, like this:
http://ecx.images-amazon.com/images/I/61B-6-wJrJL.jpg
B&D Edge Hog (brute force torque monster)

These are common garage sale finds, people buy them and use them once or twice. After a few years, she who must be listened to says it's got to go. Once you take the guard off, there is enough room to rig up a method to drive nearly anything with pulleys or gears.

Not sure what this motor came from but it's a little low on torque. It's a 3/4 hp and 3500 rpm. It have a larger one that is 3/4hp and 1800 rpm from a grain bin aeration fan that I'm going to swap on and try

Any chance of using a 240v motor?

You'd have less line loss and 3hp 240v motors are somewhat common.

This motor actually says 120 or 240 but I haven't looked into what you have to change to run it on 240

Usually you can rewire them by opening the case or cover where the wires run in. If you're really lucky, the frame will have a diagram on it. Also, electric motors are rated different than gas motors in HP. Usually a gas motor is overrated compared to an electric. For most applications, you can substitute a much smaller electric motor.

Motors often have a continues and a peek hp, gas engines are rated in peek hp.
Motors almost never list their peek hp as their rated hp.

If you can, wire that motor for 240v, even if you use the same 12 gauge cord, you will be producing less heat in the cord and having the voltage drop less, allowing the motor to do more work per watt pulled from the wall.

So if I re-wire the motor for 220 is it still producing the same hp just more efficient?

The air compressor that I rewired had more starting torque at 240 VAC than it did at 120 VAC. I don't think it would be anymore efficient unless you are nearing locked rotor amps from burdening the motor down on 120 volts.

It is underpowered on 120. I'm just not sure if I should switch it over to the 1800 rpm motor right away or retry the 3400rpm one on 240. The 1800 rpm one does have the wiring diagram on it so maybe it would be worth the swap...

That tiller you have is a walk behind model, maybe Arens. The 5 HP gas engines I'm familiar with would spin the tines fast at 3600 RPM. 1800 RPM would probably do, but might be slow. Try one and see if it works. A fuse or breaker would be a good idea, just in case...
If you have an electric motor made for high torque applications, that would be ideal.

The rule of thumb is 1 electric HP = 2 1/2 gas HP.

The losses in this rig will be mostly in the extension cord that supplies power to the motor. The power used by the cord is related to the square of the current that runs through it. The instantaneous cord losses at 240 Volts will be 1/4 the losses at 120 Volts throughout the range of normal operation. At high load, the losses will be even less, due to the cord not heating up and losing even less peak power.

If you've ever used a table saw, air compressor, arc welder, or other power hogging device on the end of an extension cord, you have probably noticed that the thing doesn't start up as easy after it has been running for awhile (if at all). If you've had lights running at the end of the cord with the device, you would have definitely noticed how much the light dims when you start the machine. Plenty of people have murdered their expensive power tools and blown fuse after fuse trying to run them on too long and/or thin of a cord.

This is the main reason why industrial power equipment is run at 480 Volts or higher. Due to the reduction in current draw, it is much safer and cheaper to run a step-down transformer near (or in) the load, and run much smaller wires between the source and the transformer. At the same load wattage, the source current is 4 times smaller, and the I^2 losses are 16 times smaller than at 120 Volts. So instead of pushing 20 Amps through the wires, they only need 5 Amps.

Any updates on this project?

Haven't got back to it in awhile no

Since it's weeding season I finally got back to this. Pulled the tines off and mounted an 18" cultivator shovel (same width as tires) and a depth pad. Since this is just a weeding machine I thought this would be more efficient. It wouldn't dry the soil as much, shouldn't grab the plants with the tines, and should use less power. Well it ended up working much better! Motor went from growling and getting hot/stalling to idling along barely working. Doesn't pull in stringy plants like peas and doesn't fling dirt/bury leafy plants.
http://i245.photobucket.com/albums/g...ps5qosz6vs.jpg
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Sounds like a nice upgrade. Thanks for sharing.