Thread: 1940's r.c. wheel chair build, finally under way. :) (drill hack)

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Some of you have already seen my 1940's wheel chair i picked up for a song. (delivered to the door)
It's has always been the plan to turn the chair into a full out rc unit, while maintaining the chairs original look.


I didn't have a clue when it came to r.c. unit's, and with the low tech method's I'm using, the local hobby shops seem to want no part in helpin me out.
After lots and lots of scratching my head, I think I have a solid plan of action.

I picked up a futaba T4YF 4 channel radio ($130 all servo's and batteries included) and 2 cheap drills (power xt lithium ion-$30 each)
I'm up in canada, and I'm sure these items can probably be purchased cheaper state side.

Now I will have to change out one of the stick's on the radio, but we'll get to that later.

So here's the basic unit.

The entire assembly will be hidden under the seat.

Once stained, you should hardly notice its there. (this unit will also be easily removed to return the chair to its natural state.)

Now i didn't have the money to purchase expensive speed controls for these larger motors. Instead i wen't with a low tech drill trigger hack.
These trigger assemblies are easy to pop apart. (couple plastic latches)
Trigger mods:
1. remove the trigger return spring. (we don't need it, the servo will do all the work)
2. Theres 2 small springs inside the slide mech/variable resistor. I cut a few wraps off each to reduce friction. (these are cheap drills with rough trigger movement)
If for some reason, you cut your springs too short, you can always stretch em out. If there 2 short they won't make a good conection. no connection, no worky worky.

The rest is easy. I just bent a piece of harded steel rod. heated it up and forced it through the trigger. a couple pieces of wood to mount too/hold the trigger assembly and your golden. (you'll have to fine tune your servo to do a full sweep of the trigger)


The reverse switch was approached in similar fashion.

Reverse mod's
1. theres 2 small springs inside making the contacts. I cut a few wraps off each to reduce friction. (same rules apply)
2.If you look close at this pic, you'll see the dirrection selector was cut in too places.
The back of the white dirrection selector had a spring type piece of plastic that clicked into place (forward/neutral/reverse) this was removed again to reduce friction.

You'll have to repeat all this for the second motor.

This is a 4 channel radio. (sticks go forward/backwards and side to side)
Each stick will control one wheel (Just like skid steering on a tractor/lawnmower/tank) with the forward reverse motion.
At any point in time the sticks can be pushed to the side to throw set motor in reverse. (the drills dont seem to mind being but in reverse while under power)
The throttle can still be used in the reverse mode.

Made a couple mounts to hold the motors, and now I'm ready to tackle the drive units.
All in all, for aguy that has no experiance with rc stuff, I'm quite pleased with the results. (I really wasn't sure if the drills would work or be a $60 waste of time.)

Forgot to mention, before i started all this i set the chuck of the drill on the wheel to make sure the drill had enough power to move the chair. I'm happy to say there's more than enough power to move the chair with one drill, and I'm using 2 drills.

Love that chair, and great effect with the drill hack post a vid when you get done..........

Icy,

Excellent job of working with what ya got. Using the speed control and the forward reverse from the drills was outstanding DIY haunter work. The way you have it set up, with using both forward reverse units, the chair will be able to spin in place which is really cool.

Have you worked out the top speed? What is the max RPM on the drills? Looks like your drive roller is around 2" in diameter. That would be around 6" per revolution. Most drills of this kind max out around 1800 RPM. So if that is the case then that would be 10500 inches per minute. That is about 900 ft per minute. That is around 10 miles an hour. That is pretty good.

Icy,

By the way. For anyone else that takes a look at this build. You could do it with just two channels. One servo could cover both the speed and direction for each motor. If your arm that controls the speed was set exactly 90 degrees from the speed controller, then moving off dead center to each side would pull on the speed control. By using large round servo arm you could cut it so it had one section that was raised exactly 180 degrees away from the arm to the speed controller. This would be a cam to actuate two micro switches. Both wired normally open with the common being reversed on polarity. Each switch would be positioned just away from the raised area or cam. As the servo turned one switch would get activated and complete the circuit to the motor. The other would remain in the valley. Then as the servo rotates back to say the opposite side the two switches would hit the neutral point and then the other switch would get activated and it would offer the reverse polarity to the motor. Just another way of approaching the electrical aspect of the build.

this is exactly why i love this site. so creative and so willing to share!!! Great job! i cant wait to see this in action

Love this build. What did you use for the drive roller? It looks like a skateboard wheel.

Spinman, where were ya 2 days ago.lol I know you where probably right here, and i should have asked. my bad!

Well now I know I could have done this with 2 chanels. I can always add a marine portable air horn to the rigg. (I'm an evil jerk) We'll wait for version 2.0 though. (I'm dying to take this for a spin)
I do have a question for you. can i replace the right stick on the control (self centering) and replace it with a throttle? (not self centering)


10-15 miles an hour is probably right. I didn't do any math, I just used the drill with the chuck as the roller to test. the higher speed seemed a little fast (drill has 2 settings) in the lower setting, it I'd say its as fast as a brisk walk.
The skateboard wheel (on the money frankenfrog) is a little larger than the chuck and i figured i could ajust with different sized pullies/gears between the motors and drive shafts.
(still unsure if i'll use gears and chains or belts and pullies)

Thanks guys and gals for all the kind words. I will be sure to post video when I'm finished.
Come april 29 I'd like to be wheeling this baby around at "shock stock"
It's london's first short horror flick convention/contest.

Coooool!!!

I've had my eye one an antique wheelchair (two actually, one like yours and one that was solid wood slatted seatback - both early 1900s) and they want anywhere from $200 to $400 and I just can't justify it considering the storage.

I never even though about making it R/C! I hope you post a video of it in action!

Awesome build. Never would have thought you could use a couple of drills to make a robot out of something Definitely get us a video of it in action.

You know, you could also find a pair of speed controls for those motors for cheap. You would have to use car speed controls (ones with reverse), and setup the throttle stick with a centering spring- stuff that can be had for cheap from somewhere like hobby king.

Not sure what the frequency laws are in Cananda, but be careful when you get around modelers- that particular radio system was designed to be used with aircraft only

Icy,

I am glad you saw my response. I was kinda wondering how you were going to use the radio control. Part of the challenge is that you are not just controlling speed, you are controlling direction with speed. So I do not see how you can use one stick for that. You have a servo for each motor to control the speed. So you need two channels for that. You must use two or no steering. If you set the linkage as I mentioned then the self center won't hurt you. In fact it might help. Maybe what you can do is run both paired servo's on one channel. One stick one motor. Neutral on both is no speed controller and direction in neutral. Then if you move the stick up, the speed controller servo will pull on speed control and the direction servo will push or pull the direction servo to forward. This will mimic the tank control you want. You can control two servo's with one channel. Just use a Y split cable. I think this is the solution for you, unless you use the micro switch ID. The other two channels will be tricky to use as they involve the stick being off center. If you pull one stick down and the other up the chair will spin in place. Both sticks back and the chair runs in reverse. Off center stick, the response will not be too good, but I have an idea for that. If you can find a way to spring load the speed controllers to off, then you can use a cable pull from the servo. Just mount the servo with the horn arm centered at the speed control and place a post with an eyelet directly inline between the servo arm and the speed controller. Then use a small control cable through the eyelet. This way when the arm moves to the side it will pull the controller much quicker and sooner. But the controller will have to be spring loaded to want to return to off. The problem with the use of the servo in the fashion I have indicated is that there will be very little movement of the speed control in the first 30 degrees. The other option is to return to the cam idea. A larger servo disk could be ground to act like a cam against the speed control. If you really want to get fancy and have the tools, you could cut a curved slot in the servo disk. Cut a slot in the speed controller arm and have it captured in the slot of the servo disk with a pin. This would eliminate the need for any spring loading of the controller. If you want to talk about this, then send me a private message and I will give you my number.