It is quite cheap and easy to build and does not require a lot of sklls. On top of this, the result is fun and very enjoyable.
Let's make RC pipes, people!
Step 1: Idea
You can use a variety of cordless drills for example. The same is with the wheels and the pipe. It could be shorter or with a bigger diameter. It all depends on how you want it to be.
I used two medium sized drills - some cheap ones to be honest. They were powered with 12V batteries one of which is in the RC Pipe.
Step 2: Battery
Newer drills may have smaller and lighter batteris that may be Lithium - this is not bad. In my case it is Ni-Mh. It gives around 30-40 minutes of spinning the pipe around. The recharging time is around 3 hours.
The battery ends had some wholes in them and I used two screws to place all the cables on them.
Step 3: Transmitter
In order to easily control the RC Pipe, I decided to extend the controls using 4 pish-bittons. The green ones give one direction, the red ones give the other direction. It was easy to drill four holes and solder eight wires making the new controlls in parallel with the standard ones.
For example the left pair of buttons: Green one is soldered to Front leaver direction; Red one is soldered to Rear leaver direction. The right pair of buttons corresponds to the left/right leaver.
At this step it is not important which one is which, just do not mix the leavers. You will always be able to switch the Green/Red buttons.
Step 4: Receiver & Motor Control
In my case I used a 5V stabiliser. You can use any 5V voltage stabiliser - it is quite spread now and easy to find (dirt cheap also).
This is the only modification to the receiver done!
The motors can be controlled in two ways:
1: On/Off relay switches: means motors will be either on or off - no smooth starting and no speed control, big starting currents and motors' brushes will be more loaded :(
2: Drill speed control + On/Off relay switches: motors will start smoothly - won't load the brushes ;) and there wont be large starting current! ;) BUT there will be a need to add something that will mimic the hand which pushes the drill's trigger for the smooth starting.
Motors are controlled very simple. As the motors are big, you cannot power them from the donor board directly. Use four relays that are controlled from the receiver outputs. All you need is the motor current passing through the relays when the desired channel receives signal. I noticed that the receiver outputs are around 5V, despite that the 12V relays still work. You can use 6V relays if you find - it is perfect. Do not forget to solder a reverse-biassed diode on the relay input. It frees the coil from the current when you switch the relay off! Check the diagram!
You can also see the antenna wiring.
Step 5: Smooth Start
I used one of the controls from one of the drills. The thing that pushes this control is a system taken from car headlights regulator. It operates by moving a rod forward and backwards. This helped me push the speed control. It also works at 12V.
The idea is that this moving rod is controlled from the receiver. If any of the four channels receives a signal - the rod extends and pushes the speed control. Then current flows through this control and also through the relay of the channel which is opened - then the motor spins.
You can see the swithes that limit the end positions of the system.
Releasing all the channesl (receiver does not receive anything) returns the rod to its inital position and waits untill you press a button on the receiver to go again from 0 to max speed.
Step 6: RC Pipe Body
The small holes that you see on the caps are for the nuts tightened on both sides. The bigger hole is for the power connector. Another hole is made on the wheel to allow you to get access to the nuts and the power connector.
The hole on the side of the pipe is for the on/off swithch. It is a simple jack that needs to be shortened to power the RC Pipe on. From the inside all the circuitry is connected after this switch. The connectors I used are shown - just make sure you use something capable of passing 2-3 A current without heating or melting.
Step 7: Motors & Wheels
The drill's chuck is held on its thread and in the centre there is a bolt, that is screwed but in the other direction.
The same method is used in my project, but you won't be able to central bolts. The wheels and the bronze bushes are unseparable now after some riding :D
The motors are held to the side caps using two screws each. It all depends on the type of drill you buy and may vary.
Step 8: General Finishing Job
It is convenient to make some holes in the white plastic and run the cables through. Where this is impossible I cut the plastic a bit to fit the cables next to the inner side of the pipe and tightened with cable ties.
Step 9: The Tail
I hope you like my project! Enjoy!