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Picture of RC Riding Lawnmower
This is my first attempt at an instructable . I have virtually no experience in electronics but at 80 years old I figure you are never too old to learn. Mowing the lawn was getting to be quite a chore so I decided to build an easy to use mower that I could either ride on or sit on my back porch and mow from there. I bought a used electric wheel chair on Craigs list for $100 to start the project off. After stripping wheels, motors, and battery box I mocked up the chassis with 2x2" lumber  This also allowed me to fit the donor mower to  the frame. I used the deck from an old Briggs  22" walk behind push mower. Once that was done I welded up the steel frame from 1 x 1/2" steel tubing. I tried building the electronics from a previous project in Make but I just didn't have the talent or experience. I decided to go with a Sabertooth 2x25. I already had the motor wiring and was set up for 24 volts. The folks at Dimension Engineering were a great help in advising me how to set up the DIP switch. I got a used 54 MHz. RC set up from a friend who fly's model airplanes. The Sabertooth is a no brainer to hook up. It even supplies the 5 volt power for the receiver. A switch, and fuse were all I needed to complete the job.
 
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Step 1: Materials

Picture of Materials
STEP 1

Materials                                                                                     

Used Electric wheelchair                                                        $100.00
Steel Tubing                                                                              $25.00
Donor 22" mower                                                                      $ 25.00
Sabertooth 2x25                                                                       $125.00
Lawn mower batteries  (2)                                                          $68.00
Misc. Nuts, Bolts, Switch , and fuse                                           $15.00
Used RC TMX, AND RCVR                                                        $35.00

TOTAL                                                                                       $393.00





Step 2: DEMOLITION

Picture of DEMOLITION
Before taking the old wheel chair apart, look it over and see what you can use in the project. The motors came with a built in parking brake that puts the motors out of gear. This was handy for testing out the controls. The castoring rear wheels came with a nice bearing set up which saved a lot of work. The battery box was designed for U1 batteries and had a nice post mount for the removable seat. The chair came with a 24 volt charger, which I saved along with the charging plugs. I saved all the wiring from the motors to the batteries because they had very nice plugs and connectors with polarity indicators. I saved the joy stick and associated electronics for a possible future project that does not require a radio. The seat plugs into a pedestal built into the battery box. This makes it a riding mower complete with seat belts and arm rests.

Step 3: The chassis

Picture of The chassis
Building a wooden mock up of the chassis saves a lot of mistakes and wasted metal. My best friend did the welding for me. My eyesight doesn't allow me to see well enough thru a darkened hood. He did a great job with his TIG welder. The wheel chair originally had the drive wheels in the front. Remounting them in the rear was an easy task using the same mounting points with motor pointing backwards instead of forward. The donor mower deck was then put in place to set up the overall length and position the front castors. This was also a good time to position the battery box for clearance with the deck. The final step was to fashion an electronics deck in the rear.

Step 4: Suspend the deck

Picture of Suspend the deck
A fresh coat of paint makes an old, rusty deck and motor look like new. Start  by positioning the deck where it won't interfere with the front wheels and the battery box. Raise the deck on wooden shims to the desired lowest cutting height. Set the wheel adjusters to the lowest point.
Fabricate four straps to hang the deck. The top is bolted to the frame, and the bottom connects to the old wheel mounting axles. This allows the height to be adjusted just as it did on the old push mower. .The deck tends to sway fore and aft, but once the desired height is obtained simply tighten the top bolts and it will be stable. If you have planned your mock up properly there should be ample room between the deck and the front wheels. Shorten the pull starter rope and be sure to dis-connect the dead man switch. I installed a small push pull switch to kill the motor.

Step 5: The Sabertooth 2x25

Picture of The Sabertooth 2x25
The Sabertooth 2x25 by Dimension Engineering is really a giant in a small package. It provides everything and more than I need. The DIP switches allow it to be programmed  to control the mower any way you choose. It has a built in fail safe that shuts down the system if you lose RC signal. The 5 vdc regulated power supply provides adequate current for most RC systems. The specs say that if you load it up with too many servos it may require additional power, but since I am not using any servos there is no problem. My Sabertooth is mounted directly to a steel plate and I have not noticed any heat build up. I am sure this unit is capable of much more than I am using. It comes with 4x40 mounting bolts for easy mounting.

Step 6: Installing the motor controller

Picture of Installing the motor controller
Now comes the fun part!  It is a good idea to put in a terminal strip between the power and the Sabertooth 2x25. This isolates the on/off switch and the fuse from the controller. Connect the positive lead from the charger to the hot  side of the switch. This allows the batteries to be charged with the switch off. Hook up the power and motor leads to the controller. They are well marked . If the motors don't turn in the right direction, simply reverse the motor leads. My motors had an extra pair of leads that actuated an inner relay. I hooked these up to come on with the power switch. At this time you "MUST " set up the DIP switches . If you don't the unit goes nuts when you apply power. I set mine up for exponential steering. You can opt for tank steering . (Read the DIP switch instructions that come with the controller)

Step 7: Installing the RC receiver

Picture of installing the RC receiver
Positioning the RC receiver is critical. It must be placed as far away from any electrical interference as possible. If you have limited range on your mower move the receiver to another location. I'm not an RC guy, but I have been told that 12 inches should be enough. The standard servo leads come with 12 inch leads I think you can also wrap the receiver in aluminum foil to shield it. I mounted it to the frame using two sided foam tape. Try to keep the antenna away from electrical noise. I taped mine to a 36 inch x 1/8 dowel.

Step 8: Final assembly

Picture of Final assembly
 
My chair didn't come with batteries. U1 wheel chair batteries are quite expensive. A trip to the local auto supply and I found heavy duty garden tractor batteries rated at 360 amp hours for $34 each. I have run for two hours or more and did not run out of power. The volt meter still showed 24 volts. I plugged the seat into the battery box and was ready to go. The blue led was not visible due to the cover plate . I hooked up an old 0-30 vdc meter and an old 24 volt light as a precaution to remember to shut off the main switch. I fashioned a 36"' dowel to attach my antenna behind the seat. I plan to add a pair of foot rests just for comfort.

Step 9: RoadTest


Now is the time that I wish I had spent more time playing video games. It takes a little practice to get a smooth turn and a steady straight run both forward and reverse. I have the DIP switches set up for exponential steering. That lets me control the speed and direction with one joystick. This is the way most wheel chairs are set up. The way my  transmitter is set up, the left joy stick is used for the throttle and has a ratchet built in. This was confusing when  I tried to use tank steering. I did try to use the left stick for forward and reverse and the right stick for direction. This seemed to work okay but I am more comfortable using just the one stick. The really nice thing about the Sabertooth is that you have the option to configure it any way you choose. My radio is very old and requires a long antenna to assure adequate range. My yard is 200 feet long and I had no problems once I moved the receiver away from the wheel motors. If I had a larger budget I would buy a
2.4 GHz system. These new systems only require a very short antenna, and are far more tolerant of noise. The new Spektrum 5XDE is available for $99.00.
This was a fun project and is attracting a lot of attention from my friends and neighbors. The model airplane club that donated the radio is having a ball running it up and down the grass runway. The surprising thing to me is the way young kids can zip it around with little effort. I don't however, let them ride on it for safety reasons. Except for the welding I would considerthis an easy project. The wooden mock up chassis would have worked just as well, but I don't think it would have held up over time. I will add a video as soon as I can borrow a movie camera. Feel free to contact me any time.
mickeydee
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eda33 months ago
nickr65 months ago

This may seem like a silly question, But will this only drive forward or will it go in reverse as well?

Thejersey2 years ago
I am trying to build a rc wheel chair n i am looking to see how the wiring hooks up to the chair to the remote do you have a diagram?
Partybot Thejersey10 months ago
The sabertooth seller has diagrams, but the only "chair wiring" you use are the power leads off the batteries and motors. You eliminate the onboard controller and joystick.
BoyWonder620 11 months ago
Awesome! Like "Honey I Shrunk The Kids!"
mjhill43411 months ago

I have a perfectly good heavy duty power chair that everything works! I wonder how hard it would be to just put a deck up in there?? But it has the joy stick and all that work Great! I just can't sell the dang thing so i might as well build something with it! BTW! Great Job!!.. :)

justbennett made it!1 year ago

I was a bit lazy and short on tools. I just used the mower deck and the wheelchair frame screwed together with leftover hardware (and, yes, some bailing wire). On the front of the deck I bolted on an angle bar and put casters directly on that. There is no height adjustment with this arrangement, but it works!

20140524_092607.jpg
jjagtiani1 year ago

Hi mickydee,

great project. I made one myself. How did you make the kill switch with RC - what type of switch and hookup did you use. I have a futaba radio similar to yours connected to 12v deep cycle battery to power the mower - works great just need a kill switch. any info you can provide will be helpful. thx -jj-

Powerwheels drives work well for some things. I built a robot using one and used H-Bridges and mixer from Carl at Diverse Electronics + 75hz Futaba controller.
teknohawk1 year ago
Amazing!
mickydee (author) 2 years ago
I put the 30 amp fuse in series with the positive lead just in case a direct short should occur I used the terminal block for easy connection of accessories such as charger and voltmeter. It keeps things neat and tidy. The only way to destroy your Sabertooth is to hook up the 24 volts backwards On my new version I am building I am using two 350 watt 24 volts Chinese geared motors. They should pull 14.6 amps.
(350 / 24) I have that circuit fused at 20 amps. inline with the positive terminal to the Sabertooth. I try to protect the controller in any way I can.
I used a 30 amp fuse because It was handy.
.
osstekz2 years ago
I have 2 -12vdc35aH in series w/ positive going to a master switch, then straight to Sabertooth positive terminal. I assumed Sabertooth would handle amp surge so i dont have your 30amp fuse & terminal strip solution. Can you explain the need for 30amp fuse and exactly how it's wired? Thanks for a great DIY learning experience!
fireplace2 years ago
what about electric brakes how do you wire them to make them work.
mouse00792 years ago
I have an electric wheel chair base with motors but I would like to know where you got your Sabertooth contorller from and as far as a radio goes I can get one from Ebay. I also have a twin blade mower deck that my chair base will be pulling and I plan on puting it on here when I'm done with it. Thank you for your answers.
Hi mickeydee,

Great instructable, I have been inspired, and nearly have all the parts!

I managed to pick up a cheap wheelchair on eBay that actually had two fantastic batteries that hold a good charge. The seller thought that they were flat and useless! The problem is that after charging the chair and testing it out for power, I am doubtful if the two 180w motors will push the RC mower up a hill (I am not building one with a chair, and hence it will not be carrying a passenger up hill). What do you think? What size motors are you using, and would it make it up a 30 degree hill? I am not sure if the motors will be too weak, or if the wheelchair motor controller is limiting power.

Your advice would be much appreciated.
mickydee (author)  Lazygardener2 years ago
Hi there!
Sorry about the delay, I have been traveling.
I don't think you will have any problems with power if you are using wheelchair motors. I am using 13 amp motors on mine. That equates to 312 watts..(Volts times amps = Watts. Using that formula it looks like you are using 7.5 amp motors. That seems a little light for a wheel chair.
I don't think you will have a problem though. I hope you will be using the Sabertooth 2 X 25 . It delivers smooth power to the motors even at very low RPM.
Let me know how you are doing
Happy building
Mickydee
artxty2 years ago
hi, i've been inspired to do likewise after i saw this project.
btw, can i use a 4 channel remote radio for this project? or it should be 6 channel radio transmiter?

tnx
mickydee (author)  artxty2 years ago
Hi there
You only need two channels. One for forward / reverse and one for left / right.
You can set it up for one joystick (serial) or two sticks (tank steering)
depending on how you set up the Sabertooth controller.
Complete instructions come with the Sabertooth .
You don't need any servo's.
I used one joystick as it felt good.
Have fun as this is a simple project.
Mickydee
dus72 years ago
Thanks for the instructable! I took your idea and made a drivable plane for my church for a kids event (no, they didn't drive it. lol) I didn't have the funds for the motor controller and couldn't get my homemade one to work (I tried arduino with some 2n3055 transistors and also made a pwm circuit using the transistors, but couldn't get it right in time). So I just used some relays and went to 12 volts. You can imagine 24 volts with relays would make this thing raise a wheelie. Don't ask me how I know. :-)

Oh, and the propeller motor is from a broken drill. I rigged it up with a switch and it spins.

Here's the pic, thanks again!
photo-3.JPG
mickydee (author)  dus72 years ago
Your project seems like a great idea. I think maybe I will copy you and build something for the little ones at our church. We have a big back yard and we occasionally set up inflatables for our youth. I think I will build a little train with a couple of cars. The wheel chair motors have plenty of power for that.
Thanks for the good idea
Mickydee
Perfect Instructable and an amazing project!! You just made my day! I'm envisioning all sorts of projects using an electric wheelchair as the platform now! I think a miniature electric powered tank with a fiberglass body is in my nieces' and nephew's future!
mickydee (author)  Brian Henderson3 years ago
Thank You
Sounds like your little ones are in for a fun time. The wheelchair motors are powerful enough for just about anything you want to build, and the range with U-1 batteries is very good. I have mowed my lawn 4 or 5 time between charges and still had power to spare. Check out my Sitway instructable for another use of these motors. I been playing around for at least a month and I haven't had to re-charge it yet. Have fun and let me know how you are doing.
mickydee
derek_eide3 years ago
You've inspired me to make one. My brother is in a wheelchair and I know he'll love it. Thanks.
mickydee (author)  derek_eide3 years ago
Thanks a lot
If I had it to do again, I think I would have spent a little more and used an electric start motor. If you make one for your brother, this would really give him a feeling of independence . My motor starts easily but I am not bound to a wheelchair.
I wish you all the success in the world. It is not a difficult project
mickydee
TinRobot3 years ago
This is awesome work. Thank you for posting this ible. Soooo invious! I would love to make this for my son.
Awesome work MickeyDee! Keep them coming!

Paul
Great instructable!

This one is a real improvement on the RC lawnmower concept i saw recently by johndavid400.

I hope that should i make it to your age, if i can be half as productive and show as much ingenuity as you then i will have lived a happy and contented life. BTW - can you adopt me Mickydee?

mickydee (author) 4 years ago
I have tried everything I know to download a video into this ible. I uploaded to you tube and tried to down load. to this program. No luck, it keeps telling me that the file is too big (over 10 meg).
I would appreciate any help to solve this. I know it can be done ,because I watch other peoples video's
Thanks
mickydee
If you still need help uploading a video, let me know and I will walk you through it.
tigerbomb84 years ago
sorry to say mate but it was done 1 year ago
http://www.instructables.com/id/Arduino-RC-Lawnmower/
Even so, it is still really cool.
oh booo....
tchang20104 years ago
very nice project micky, the instruction is very clear. I might do something similar to your project this summer. Thanks for the information....
-thai
mguima4 years ago
That´s how I would like to be at 80.
dubdryver4 years ago
SPECTACULAR PROJECT & WRITE UP! Very well thought through and executed!

I couple questions about how well it works?
Does the unit drift often, and do you find yourself correcting the steering often?
I am sure you adjusted the trim on the transmitter to compensate.

I am very impressed with the runtime, and your setup would blow a kid's motor powered car out of the water! It seems like your project does not suffer from getting stuck on low ground or cement edges.
I would like to make a little car to let kids ride around in that way I would have better control of where they are going, and if made correctly, I could jump in with them :P I could also put a pull behind mower as an accessory.

Thank you for the inspiration Micky, very well done for your first instructable!

mickydee (author)  dubdryver4 years ago
This setup would make a great small kid's car.. I don't notice much drift once the castors true up.. I imagine you would put in a steering wheel, if you built a car, so yhe only controls you would need would be forward and reverse. My motors are 13 amp each. They can run on either 12 or 24 volts. Top speed would be slower with 12 volts.
I tried it on 12 and didn't seem to lose much power. I think the range would suffer though. Great idea! let me know if you build one and maybe I will build yours for my grand kids.
mickydee
I actually don't have any kids, but I like entertaining my friend's! I think they would have a ball with such a thing! There are parks near by and we could go riding around. It just all around seems like a very cool project!
It will have to probably wait until this winter when there isn't as much activity going on, that way it could be ready for spring!

I would actually prefer the remote control over a steering wheel so that "we" the grown ups would have control over the vehicle. They like to rid their bikes into things, and occasionally people!

I would probably work towards aluminum, fiberglass reenforced wood, or steel butted tubing similiar to what is used on bikes to reduce the weight some, and add some efficiency. I have quite a bit of time ahead to brainstorm the process. I am just thankful for your footwork into the "meat" of the project which is where all my questions would have been. Anyone can build a box car, but making it electric and remote controlled is where it becomes fun!

Thanks again Micky, Best Regards!

Josh
ducktape1004 years ago
cool how long did it take you to make it
mickydee (author)  ducktape1004 years ago
I didn't really keep time when I built this. Mocking up and building the. frame took two Saturdays. Taking the wheel chair apart took a couple days. Thinking and planning took ar least a week. Add another couple weeks for assembly and electronics testing
I guess it probably took about a month
mickydee
cool that did not take that long
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