I needed a cordless drill to do some outdoor drilling, but I did not want to spend $200-$300 for a 18v-24v cordless from a store shelf. I got a cheap 6v cordless drill that I up graded by replacing the motor, the circuit ,the batteries; and I made box to hold the 16 C batteries. After the fabrication and assembly, I tested it and found that it was almost as powerful as my 120v AC corded drill from Skil. The price of this project would be $30 for the parts, $8 for the alkaline batteries, $40-$70 for nickel cadmium rechargeable batteries.The price depends on the quality of the drill I started with which would cost around 30$. If you have to buy an inexpensive cordless drill, and do this conversion, it will still be cheaper than an expensive cordless drill.
Please note that the photos are in mirrored image.
Step 1: Tools and Parts List
1. soldering iron
2. circle guide or compass
3.solder (I suggest lead free)
4. electrical tape and masking tape
5. screw drivers
6. alligator clips
7. wire strippers
8. small hammer
9. red and black markers
14. hand saw
17. wire cutters
18. super glue
19. volt meter or you could use a battery,
light bulb and wire instead to check conductance
20. drill bits
22. hobby knife
1. a metal or hard plastic box
2. metal sheet (I suggest aluminum)
3. battery holders
4. 24 volt motor
5. electrical connectors
6. insulated wire
7. small plastic box from an adapter
8. steel wire
9. 16 batteries
10. 4 button
11. coat hanger
12. CD box
The 1.4 hp motor it is normally used for RC cars, I got this one at a local hobby store for $10, if you can't find it locally you can get it at http://www.robotmarketplace.com/products/0-HTIM1.html
I found a good source for rechargeable battery's at http://www.cheapbatteries.com/nicd.htm I suggest
that you only use nickel cadmium batteries because they can be charged easily, just supply power of 1.7V multiplied by the number of 1.2V batteries, connect in Series or 1.7x) other batteries need a more complex charger.
The four buttons on the second slide of this page are not the same. The two blue buttons are on when at rest and off when pressed and the two red ones are off when at rest and on when pressed.
This will be explained later .
Step 2: Disassembly and Modification
Step 3: The Battery Assembly Wiring
Start by stripping the insulation on all the wires, then cut the wires on one of the battery holders then cut the battery holders. Connect all the battery holders into two sets of eight battery circuits. Place electrical tape on all the connections and place all of the battery holders in the battery box except for one. Trace the bottom of the drill then use another drill to make a quarter inch hole in the top of the battery box after removing the lid from inner components. Place the lid back on then feed the four wires though the hole. Place a connector on three of the wires and the fourth being connected to the last battery holder, then to the fourth connector. Be sure to lablel the connectors , remember there are two separate 12V circuits.
Step 4: The Battery Assembly Connecters
Step 5: Clamp Asembly
Step 6: The Mechanical Mechanism
Step 7: Electronic Mounting
where we will be mounting the buttons in the shell of the original drill. The red button in the back is used to turn the motor on and off, and the other red button as well as the two blue buttons will be placed at the trigger arranged so that they will move as one and be used to change the voltage from 12v to 24v.
Step 8: Wiring
This part is fairly simple but this can be frustrating if you don't know how the wiring is arranged. If you are uncertain with circuitry then I suggest that you follow my instructions exactly. if you are good with circuitry then you could make your own circuit.
Take note of of the battery pack, the four leads should be labeled P1,P2,N1 and N2 the P stands for positive and N is for negative, in my case P1 and N1 are connected and will have 12V and P2 N2 are the same but insulated .
For the wiring, refer to the twelfth, thirteenth, fourteenth and fifteenth pages
wile viewing page elven and twelve. Follow the wiring list given. All of the points on the list should be soldered as one in each column on the list .
w1 w 2 w 3 w 4 w 5 w6 w7
P1 N1 P2 N2 E2 M1 M2
C1 A1 C2 A2 D1 F1 F2
B1 E1 D2 B2
Once you have done all of this you might want double check the circuit for shorts or any other problems, then you would have what is seen on the first image.
Step 9: Completion
If you want to go beyond alkaline batteries and make your drill rechargeable, you need to get some Nickel-cadmium batteries. I suggest that you only use Ni-Cd batteries because they are easy to recharge ,you just supply power positive to the positive and negative to negative (the voltage to recharge is 1.7v multiplied by the number of battery's in Series or 1.7x) Other batteries such as Ni-Mh or especially lithium batteries need a more complex charger.
Whether you get Ni-Cd or something more advanced, you would insert all 16, 1.2V battery or 6, 3.6V lithium batteries (you will need to modify the battery box). Then what you do is to attach alligator clips to the battery leads then to the charger or power supply. You can get an advanced charger at http://www.robotmarketplace.com/products/battery_chargers_main.html and batteries at http://www.cheapbatteries.com/ or at http://www.robotmarketplace.com/products/batteries_main.html
Observe the last three images if you are unsure how to charge batteries.
I hope you enjoyed this project, leave a comment or questions and I will try to reply.
the image of battery is from http://www.germes-online.com/direct/dbimage/50060458/High_Rate_Discharge_SC_Size_Ni_Cd_Batteries.jpg