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Discussion Starter #1
I had a crazy idea sparked by the "outboard mower" thread in this forum. My dad has an asphalt driveway. The rounded edges of the asphalt make it tough to control a normal edger to trim the grass that tries to overgrow the driveway. What he normally does is walk the driveway with the weedeater turned vertically. Did I mention that the driveway is almost 0.2 miles long?

I got to thinking about the potential for converting a 12V trolling motor into a vertical weed whip. You could mount the motor to the side of the deck or other convenient area on the tractor. The Kubota B8200 he uses has enough battery and charging to run the motor for as long as it would take. Remove the propeller and replace it with some form of string head. I might try a fixed line head strung with thin wire rope. I can even envision a mechanism to trip a bump feed line head, should that prove more practical.

What I don't have is any experience with electric trolling motors. What kind of speeds do these hit? Has anyone else been crazy enough to try this kind of conversion? Any other potential pitfalls anyone sees?
 

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Trolling motors are usually variable speed so that should not present a problem. They are very heavy at the motor end. What about line feed? You would have to stop and get off every time the line breaks off or gets too short. I guess you could use some sort of hammer device to bump feed. :smilie_fl
 

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That's an intriguing idea. I'm not sure how fast a trolling motor spins wide open, but since there is no gear reduction I bet it would be plenty fast enough. Give it a quick test....clamp 2 10" or 12" pieces of trimmer line between two fender washers on the motor shaft in an "X" pattern and try it before you go to the trouble of mounting the motor to the tractor. I would be interested to know how it works out.
 

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Discussion Starter #4
First I'll have to go to the trouble of finding an OK condition used trolling motor, as I don't own one. I'm more worried about having ENOUGH speed at full throttle. I'd probably set it up with a rheostat on the electrical line to fix the speed, with a simple on-off switch. As to the bump feed, I was thinking a cable to pull in on a spring loaded lever to "bump" the feed trigger.

I want to get a reality check from someone else before I spend any significant money on this. Sometimes my reality check has bounced...
 

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Most trolling motors have been made by MinnKota and Motorguide. Years ago there were a few others in the business. I have an old Shakespeare 36 lb. thrust that has separate rheostat and on/off switch. I'm sure something like this would provide more than enough speed. You would need a transom mounted (clamp on) unit. I just did a quick check on eBay and found several used motors under $100 and a few under $50.

I think it might be difficult to follow the curves in the driveway with the tractor, keeping the trimmer line where it is supposed to be. :)
 

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I did some googling..."trolling motor rpm". Someone had e-mailed MinnKota and they replied that their motors average about 1400 rpm.
 

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Excuse me if I go at this a slightly different direction... My Ryobi trimmer is the "convertable" type, you can mount different tools to the engine shaft. On of the features of this is the ability to mount the curved string trimmer head at 90º for edging.

Add a single or 2 wheels behind the head on an "A" frame for support and go edging. I edge my driveway/parking area free hand without the wheels but it's only 125' long or so... Or did I miss the challange of invention here...?:D
 

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Cooling the motor might be an issue. Lake water absorbs heat a lot better than 90 degree air does.
Excellent point! :trink40: I had totally forgotten about that. They definitely need to be submerged if the air temp is warm.
 

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A DC motor like is in a trolling motor cannot have speed controlled by a rheostat if you're attempting true variable speed. You need proper controller electronics capable of about 30A output to do this. Some trolling motors have their motors wired for multiple distinct speeds (e.g. fast, medium, and slow); for those you would not need the controller but rather a proper switch setup to handle the multiple wires coming from the motor. Depending on the condition you can and should try to salvage those electronics/switches from the existing controls, but I suspect that failure of those electronics is usually the reason why the trolling motor was discarded.

If I were to offer a recommendation I would suggest looking for a cheapo ~12V rechargeable drill instead -- that should be attainable for around $20. You could then hard wire the drill to battery contacts directly to your mower battery.
 

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If I were to offer a recommendation I would suggest looking for a cheapo ~12V rechargeable drill instead -- that should be attainable for around $20. You could then hard wire the drill to battery contacts directly to your mower battery.
RPMs are to low for the job . Less than 1000 rpm I believe . Unless of course you spring for a high end drill that can provide 1300 rpm . Eve that seems a little slow for the job .
 

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How about a GM heater/AC blower motor,they are pretty powerful and spin at least 3600 rpms,and are compact and lightweight..hook one to a die hard and a handle with 2 wheels,and I bet you'd whack a yardfull of weeds with it no sweat!..
 

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I have a near brand new Minn Kota Endura 30 (30LB Thrust, 12V) in the box, I would let go for $75 plus shipping, pretty sure it's like a buck thirty new, and it sure would get the job done! :)


*Edit* it's also variable speed... 1 through 5 I beleive (in forward and reverse).
 

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I'm with the "to slow" crowd. I think you need 3000 + RPM to make a string type trimmer work.

Many years ago, before they were selling string trimmers for a reasonable price, I tried to make one using an electric motor from a blender. I am not sure how fast it turned, may have even been 3450, but it was not fast enough. The string would wind up on the hub as soon as it hit any thick grass.

Like HH said... many string trimmers can be turned 90˚ to be used as edgers. I like his idea about mounting a set of wheels on one of those.
 

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Discussion Starter #15
Thanks for the feedback, everyone. I'm not going to proceed with this scheme at this time. I was afraid that a trolling motor might be too slow. I'll probably look for a 12V electric weed eater that I could wire and mount to the tractor, or some other hair brained idea to make this job easier. It just takes a lot of time and effort to edge the driveway right now, and having a ride-on attachment would be a lot easier. At least I didn't waste the money buying parts that don't work.
 

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I have a 1954 march issue of Popular Science magazine with plans in it to convert an old vacuum claner into a trimmer/edger,that might be similar to what your trying to make ,only in 12V form..this one would need 110V and a cord though!...be neat if you could make one that runs off the tractors existing belts somehow...
 

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Or you could just use a 2 stroke weed eater with a shortened shaft, will run in any position, and then you dont have to worry about electrical.
 

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Have you considered making a simple bar, that bolts to the tractor.. with a V notch in it? then just resting the shaft of the weed eater in it, while holding it in one hand.. and driving slowly?

I would think that if the weed eater does a good job, then a method of attaching it temporarily to the tractor, would be cheaper and easier in the long run.

I'd personally try to build a bracket, that held the weedeater just outside of the front tire on the right side, so that it would be easy to watch, and steer.

if it was just the steel bar, with the v notch, it would be easy to lift the trimmer, bump the head to advance the string, and replace it in the notch.

Just A thought

Dave
 

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Discussion Starter #20
I'll send the link for that product. I'll send it along to my dad. The string trimmer works, but edging both sides of a 0.2 mile long driveway adds up to a lot of trimming, and takes a lot of string feedout. Mounting guide wheels or fixing the unit to the tractor would make it harder to flip the unit down and feed out the line.

My dad has a good-running Husqvarna trimmer and a simple rule about new functions - NO NEW ENGINES. He's already got too many engines, each of which gets cranky every couple of years because they don't get enough use, especially on specialized implements. This means he goes for tractor driven implements as much as possible. For little things like the trimmer, he gets a good bit of use out of it so the engine runs well. Less frequently used items like the chainsaw or hedge trimmer tend to get cranky.

He's been toying around with ideas of some form of mounted trimmer rig for a while now, but hasn't prototyped anything. Thanks for all of the help.
 
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