Author Topic: What motor for an electric tiller?  (Read 16331 times)

Tommy Jefferson

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What motor for an electric tiller?
« on: April 27, 2010, 11:05:16 AM »
I want to convert an old, busted gas tiller into an electric tiller like this one:



I don't know a lot about electric motors.  I assume the motor needs to be high-torque, low-RPM.

What kind of discarded machines should I search for?  I'm having difficulty imagining what appliances would have such a motor.

Washing machines?
Floor buffers?

Any ideas appreciated.

Offline Orionblade

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Re: What motor for an electric tiller?
« Reply #1 on: April 27, 2010, 11:25:15 AM »
Instantly springing to mind are the motors from treadmills.

IIRC, they're DC or universal motors, so you wouldn't have to worry about A/C connections, but either way, you should be able to find one for a reasonable price on Ebay.

Another option is to google some robotics suppliers for gearmotors from electric wheelchairs. They're relatively high speed motors that are geared down significantly, and should produce about the right speed on the output shaft - and they're designed to run off a golf cart battery.

Offline johngalt

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Re: What motor for an electric tiller?
« Reply #2 on: April 28, 2010, 10:21:12 AM »
I would try to get at least the same HP rating for the electric motor as the gas motor.  A DC motor with High RPM is fine, but you will need a dc drive along with it.  Then I would recommend getting a gear reducer because the horsepower/torque is greater at higher motor RPMs, Also, this usually helps to turn the motor 90° to the driving plane and will make it fit better...most likely.  Interesting project.  you have my brain turning now.

Offline Orionblade

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Re: What motor for an electric tiller?
« Reply #3 on: April 28, 2010, 10:38:13 AM »
Actually, I thought that for along time, but a motor produces it's highest torque at stall, pretty much the exact opposite of a gas engine that produces it's greatest torque and horsepower (assuming the carb and intake ports are big enough to supply the air, and the valves don't start floating) when it's about to fling itself into a million pieces. Horsepower is a product of toruqe and rpm, so that'll climb to a maximum at a specific speed, but raw torque, foot pounds, is probbably what you're looking for on a tiller that's pictured - ours is gas, and kind of crawls along, with the tines maybe running 10 or 20 RPM, and it just tears through the soil, as opposed to the little bouncy no-wheel tillers that look like a weed eater with an implement of not-instant-enough death spinning underneath. *shudders in horror*

The motor has two things going against it - back EMF (which can be mitigated/redirected/messed with a little, but not eliminated due to simple physics) and the simple fact that the faster it goes, the faster the magnetic field has to change - it basically runs out of "push" when the change in the rotor hits a certain speed.

When you use motors in robotics applications you pay very close attention to this, because you want to keep the motor close to stall by using a gearbox, but you have to have a little fudge room so the load on the motor doesn't reverse it and smash your gearbox and whatever's attached to it.

Anyhow - as far as AC vs. DC - higher voltages can produce higher efficiency systems, but I have a feeling that a plug-in tiller with an extension cord would kind of suck, and you might want to pull more amps than is advisable with 200 feet of cords, so I'd go DC or at least stuff an inverter on top.

Another option is to build a deep cycle battery and inverter into a  power box on a little trailer, and use extension cords from the power box to the tiler, and the advantage there is you have more power, and less weight to push down the row, AND you can toss a solar panel on the power box to keep it topped off between uses - and maybe even use it to run a freezer or something in a pinch.

You might also check out robotics pages for motor controllers - these can boost efficiency by using pulse width modulation - the modules are just drop-in, and you can put a potentiometer on a hand grip of some sort, as well as a little shorted headphone plug on a string, so if you let go of it and fall, it pulls out the plug and shuts down the motor controller - so you're only switching a few milliamps to turn off the controller that will shut down the several dozen amps to the motor.


Offline johngalt

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Re: What motor for an electric tiller?
« Reply #4 on: April 28, 2010, 11:23:14 AM »
Quote
Anyhow - as far as AC vs. DC - higher voltages can produce higher efficiency systems, but I have a feeling that a plug-in tiller with an extension cord would kind of suck, and you might want to pull more amps than is advisable with 200 feet of cords, so I'd go DC or at least stuff an inverter on top.

Just got a picture in my head of a guy tilling with a  480V "extension cord" in the yard. 

Offline Orionblade

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Re: What motor for an electric tiller?
« Reply #5 on: April 28, 2010, 12:59:40 PM »
Yeah. Or he could aling his rows with the high tension wires up above and just tie a wire to a tennis shoe, fling it over, and use the tiller tines for a ground connection...

10KV would do it, don't you think?

 ;D

Tommy Jefferson

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Re: What motor for an electric tiller?
« Reply #6 on: April 29, 2010, 07:32:12 AM »
Thanks guys.  I hoped I could find an old AC machine and harvest the motor from it.

The build cost of a DC motor with batteries would be equal to buying a new tiller.

My garden is right next to my house.  The extention cord would never be longer than 50'.

I'll be on the lookout for an old treadmill.

Offline Orionblade

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Re: What motor for an electric tiller?
« Reply #7 on: April 29, 2010, 09:49:38 AM »
But don't you want a portable power pack?

 ;D

Offline joeinwv

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Re: What motor for an electric tiller?
« Reply #8 on: April 29, 2010, 10:17:50 AM »
Commercial / restaurant refrigerators and freezers. Big electric motors. Most areas will have a shop that rebuilds these - probably also return alternators and that sort of work. Keep an eye out.


Offline millwright

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Re: What motor for an electric tiller?
« Reply #9 on: May 27, 2010, 12:01:45 AM »
Look for an a/c shop with a big pile of old air handlers. 7-10 ton blowers will have motors in the 3-5 hp range. The only problem is they will be 240v, probably 1725 rpm.
Check harbor freight for a gas motor.....Made in red-china fairly cheap.
My generator has a subaru-robin 10hp probably made in china, but its quiet compared to a Briggs.

Offline Dawgus

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Re: What motor for an electric tiller?
« Reply #10 on: May 27, 2010, 04:45:58 AM »
 Why not skip something that needs power completely and go with a broadfork? Broadfork Demo  I stare at 'em every time we go go Lehmans...someday I'll find a used one and park the tiller for good.

Offline johngalt

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Re: What motor for an electric tiller?
« Reply #11 on: May 27, 2010, 01:12:54 PM »
I love mine, but I would recommend digging with a shovel first on unbroken ground.


Tommy Jefferson

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Re: What motor for an electric tiller?
« Reply #12 on: May 28, 2010, 07:44:23 AM »
I now have my eyes peeled for old air handlers and commercial refrigeration units.

Thanks guys!

Offline Orionblade

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Re: What motor for an electric tiller?
« Reply #13 on: May 29, 2010, 08:41:12 AM »
What about a handheld steam cleaner hooked up to a pneumatic die grinder tool... Steam power!

Offline mobilus

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Re: What motor for an electric tiller?
« Reply #14 on: June 03, 2010, 07:09:21 PM »
TJ, see if you can find an old floor buffer with a good motor.  Those things have loads of torque and would probably turn about the speed that you want.

Offline LGM30

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Re: What motor for an electric tiller?
« Reply #15 on: June 16, 2010, 08:07:55 PM »
Electric motor HP does not equal gas engine horsepower.  Gas engines are rated at peak Hp and electric motors are rated at continuous duty.  I don't think you would need to match HP.  Furthermore you don't need to worry about low speed if you go with the same setup you see in the picture speed reduction is accomplished through the pullies.  Put a small sheave on the motor and a large sheave on the tines and you will operate at a slower speed.  If you get too much slippage find a pair of dual pulley sheaves.
One of the problems you might want to watch is voltage sag.  You should get a heavy duty extension cord so that resistance in the cord is minimized.  Otherwise it might be like trying to start an air compressor on a cheap extension cord.

Offline onesojourner

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Re: What motor for an electric tiller?
« Reply #16 on: October 28, 2011, 04:01:04 PM »
This isn't much of a how to yet so I thought I would post up what I did:

I had an old miter saw that was in rough shape so I thought I would give this a shot.

coupler from motor:


Motor coupler welded to tiller transmission coupler


first test


broken handle from saw moved up to handle on tiller


complete


The tiller worked great until I hit a piece of carpet (whooops) and the transmission shaft snapped in half. I need to see about getting a replacement.







Offline Brokin

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Re: What motor for an electric tiller?
« Reply #17 on: November 24, 2016, 11:02:02 PM »
Old thread yeah so sue me :P
But yeah treadmill power is the way to go.



Sumbitch'll dig!

Got about $10.00 in the whole mess belt and bolts.  free diamond in the rough tiller, free treadmill.

2.5 hp motor 1800w 1725rpms 3phase 220v runs off 16a 110v

Quiet as can be  ;D

Offline machinisttx

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Re: What motor for an electric tiller?
« Reply #18 on: November 25, 2016, 06:06:06 PM »
Looks like a Troy Bilt Horse or Pony tiller that's missing the rear tine cover. Around here either would sell for $200 or so even with a bad engine. I wouldn't operate it like that(I like my feet), though I wouldn't have put an electric motor on it either.

Offline Brokin

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Re: What motor for an electric tiller?
« Reply #19 on: November 26, 2016, 08:06:35 AM »
Yep it's a horse early 80s 4speed model. Used ones in good condition go for $500-1200 around me $2500 new! :o I have the tine cover just need to extract the busted bolts to reinstall it.  My feet stay behind it and it only moves forward. Has an emergency stop button that will stop the machine from full tilt to stop in 1/4 tine rotation.
 It would have cost me $500 plus to replace the rusted busted engine, engine mount and sliders. Then I would still be stuck with an infernal combustion engine. F that noise. I grew up riding dirts bikes go carts and four wheelers, while I love the sound of a screaming small block I have no desire to hear a single cylinder sing it's awful song. I much rather hear the gears and bearings humming.

Cord is very easy to manage and I have power in the shed.

Offline machinisttx

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Re: What motor for an electric tiller?
« Reply #20 on: November 26, 2016, 07:54:03 PM »
A $99 6hp Chinese honda clone from harbor fright bolts right on and produces far less noise than the original briggs/tecumseh/kohler engines. Rebuilding a briggs or tecumseh costs about half that. The sliders are just cold rolled bar stock, maybe $20 from the local machine shop. I'd imagine the mount could be found on ebay for $50 or less.

IIRC, I have four Horse Tillers and 2 of the Pony models. I buy them at scrapyards for $80 or so. Easy money for someone willing to get their hands dirty.  ;D

Offline Brokin

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Re: What motor for an electric tiller?
« Reply #21 on: November 26, 2016, 10:37:53 PM »
I know my fab skills are hack at best, I can envision but not replicate. I'm actually surprised I got 20hrs on it and it hasn't fallen apart yet, biggest hang up was not running screws to the tires from the rim. Yeah they are junk too. found a pair of tires on cl for $10 should probably not buy them so they get thrown away and I'll order a new pr for $100 plus shipping.

Maybe most here are prepping to rush the harbor freight or Canadian tire, princess auto when shtf? ::) and tell me, if shtf lol how much easier it is to make gasoline than electricity?

Guess you guys are right, we should all go out and buy some brand new fob Chinese shit, instead of using what's already around. I got half a mind to believe if we paused all manufacture of new shit we would get a good look at what's already here. Wouldn't have to make new junk for quite some time.

Then again it was an Italian treadmill


I've looked, had this tiller since 2014 as was, If you find a $50 mount let me know I would like to have reverse :crazy:

Offline Fixit

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Re: What motor for an electric tiller?
« Reply #22 on: November 27, 2016, 08:44:21 AM »
Your reverse problem is in your choice of motors . I know I know you used what you found . that said a DC motor would of reversed with a simple flick of a switch . What I am picturing is a 90-110 volt DC treadmill motor with a rectifier ,a deadman switch and an ajustable resistor to change speeds if needed.

Offline Brokin

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Re: What motor for an electric tiller?
« Reply #23 on: November 27, 2016, 09:18:23 AM »
It's a 3 phase motor, I could wire in a dpdt switch and have reverse. But it wouldn't work as nicely as the original sliding mount. I have already changed the direction of the motor so it would spin the same direction as the gasser.

The first treadmill I got was dc but only 1.5 hp, gave that one to the wifey and she's using it ;D

Offline machinisttx

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Re: What motor for an electric tiller?
« Reply #24 on: November 27, 2016, 10:25:40 AM »
Took me less than a minute to type it into ebay. http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.Xtroy+bilt+horse+engine+mount.TRS0&_nkw=troy+bilt+horse+engine+mount&_sacat=0 Take your pick, four of them for less than $40. You'll also probably need the reverse disc. Early models used a fiber disc and later ones used rubber. I believe it's mounted on the transmission input shaft, but it's been a while since I had a look.

I'll try to remember to go out to the shop and get measurements for the sliders later. They're either 3/4" or 1" diameter and around 8"-10" long as best I remember.

You are right about using existing junk vs new. I have salvaged more small engines and equipment from scrapyards than anyone else you're ever likely to have contact with. Quite often "rusted busted engines" and engine driven equipment have little more wrong with them than a poorly maintained fuel system, faded paint, and rust on non critical parts. YMMV.

Put tubes in the existing tires, unless they're so rotten that they are falling apart. Otherwise, tires shouldn't cost more than about $30 each. http://www.ebay.com/itm/D040-2-Troy-Bilt-Horse-Garden-Tiller-Tires-4-8x4x8-4-8x4-8-4-80-4-00-8-M-/261422756039?hash=item3cde02b0c7:g:V0gAAOxyrM5TIhWe I would probably replace the tires instead of putting in tubes though.

Offline Brokin

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Re: What motor for an electric tiller?
« Reply #25 on: November 27, 2016, 11:39:33 AM »
Thanks for the links. I have the original drive pulley and rubber wheel, didn't use as it is too small for the motor shaft, 5/8 vs 15/16 but I'm sure I could fit the disc on the end. Extracting the slider pins might get interesting.





I was hoping for a carb clean and new plug and oil but no such luck with this one.
Tires are flat spotted and half folded over, currently they're stuffed with rags, one wheel is missing a 1/4 of the bead area, engine needed a new carb as the brass and al ooo min e umm had become one, exhaust valve was open muffler rusted off cyl had water in it for years, not enough compression to make any usable power. a pint of water from the crankcase, some from the gear case and even some in the tine drive
Ymmv indeed,



The hack job that inspired me.

Offline machinisttx

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Re: What motor for an electric tiller?
« Reply #26 on: November 28, 2016, 08:34:09 PM »
The last one I bought needed a carb rebuild, but these days it's almost as inexpensive to just buy a new one from china as it is to buy a rebuild kit....and no worries about a corroded needle seat or stuck jets either. $15 chinese carb and it was done. Dad decided to use it to till his garden and evidently sheared a key somewhere in the transmission.  I haven't had the inclination yet to see exactly what the problem is. Tines are still turning but the drive wheels don't.

50/50 mix of acetone and ATF works better than anything else I've ever tried for rusted parts. It won't stay in suspension though, so you have to mix it prior to use.