This hand crank generator demonstrates the conversion of mechanical energy to electrical energy. Like my last project (the RC car), I began this work without any prior planning or preparation. My project completion took three months:
Month 1: continued visualization and elementary sketches, most of which found their way to the garbage can.
Months 2-3: Scavenging for parts and pieces in my high school's wood shop, and "winging" my design and re-designs with frustration and determination.
Step 1: Video Demostrations
Step 2: Materials and Tools
Hawk saw or band saw
Drill press or drill
Hand drill (optional)
1-inch wood plank (12 inches long) - $10
1/4 inch wood plank (2 pieces) (6 inches long each) - $10
Gears - $7
DC motors - $2 ea.
Metal rod (24 inches long) - $3
Plastic crank arm - $3
2 inch screws (1 small pack) - $8
Hot glue gun - $4
Hot glue stick - $4
Wires (small spool) - $5
Total Estimated Material Cost: $58 US Dollars
Image reference: Google images
Step 3: Cutting the 1-Inch Thick Wood
Using a shop saw, I cut a 1-inch thick wood plank into a rectangular base measuring 7 1/2 inches in length by 5 inches in width.
Step 4: Cutting the 1/4-Inch Thick Wood
Using a shop saw, I cut 3 pieces of the 1/4-inch thick wood planks into rectangular side walls measuring 6 inches in length and 5 inches in width.
Step 5: The 3 Shafts
The 3 shafts are just a two-foot welding rod cut to various lengths.
I used a hawk saw for cutting the rod into pieces.
1. Main shaft (8 inches)
2. Crank shaft (5 1/2 inches)
3. Gear reduction shaft (4 1/2 inches)
Step 6: Drilling the Holes
Wood Plank: 6x5x1/4-inch
(Open the pictures for additional notes on the holes)
Use a 1/4-inch drill bit to create the small holes that will become the support holes for the shaft.
A countersink bit will be used on both sides of each 1/4-inch hole to reduce friction between the rod and the wood.
Next, measure one inch from the top of the board and 2 1/2 inches from the side to the center of the board. Drill a hole on the intersection point, as indicated in the pictures.
On board 1, Drill two 1/2-inch holes, side by side (where the big black dots are in the picture). Your exact placement will vary on the size of the gear and gear ratios you intend to use. These holes are where the motors are going to be mounted and size depends on the motor sizes.
On board 3, drill a hole that lines up with the small hole on board 1. (these holes are for the gear reduction shaft)
Then on board 3, drill another hole for the crank shaft. (make sure your gears make contact before drilling the holes)
On board 2, drill a hole that matches with the second hole on board 3. (crank shaft)
Step 7: Assembly, Part 1
(don't mind the color changing gear)
For this step make sure the holes for the main shaft line up, and then screw both 1/4 in wood to the 1 in. wood like the picture above. Again make sure the main shaft holes line up before screwing it in!
Then add a small gear to the main shaft and mount it to the frame,
Finally, add a big gear to the outside of the frame.
Step 8: The Middle Piece / Board #3
First, cut 1 in. from the bottom of the middle piece
Then cut that shape off the top (make sure the wood doesn't touch the rod, like in the picture above).
lastly glue the small rectangular piece onto the shape (measures 1 inch in width and 4 in length. I found that piece on the scrap pile)
Step 9: Assembly, Part 2: Middle Piece
Screw in this piece (about 2 inches wide 6 tall, found this piece on the scrap pile) on the middle of the frame. Like the picture above.
Then screw in Board #3 into the 6 x 2 piece (to hold it in place and allow adjust ability while building the project).Easier if you use long screws for this part.
Step 10: Assembly, Part 3: Gear Reduction Shaft
To the gear reduction shaft, add a small gear to one end and hot glue it in place, and add a larger gear to the other end (about 1 1/2 in. of shaft over-hang from the big gear. Over-hang does not matter for the small gear)
Then, mount it to the frame like the picture above. (making sure the gears make contact)
Step 11: Assembly, Part 4: Crank Shaft
Glue the plastic crank to the crank shaft rod with hot glue.
Then, mount the crank shaft to the frame. Then, add a large gear to the other end of the shaft with about a quarter inch of overhang, and hot glue it in place like the picture above.
Step 12: Assembly, Part 5: Motors
Mount a small gear on both motors.
Then, mount the first motor with hot glue making sure it makes contact with the big gear on the other side.
Also, mount that L-shaped wood block (I found this piece in the scrap pile, but measurements are above) with hot glue, near the other hole like the picture above.
Lastly, mount the second motor onto the L shape wood block making sure it makes contact with the big gear on the other side.
(I had to use that L shape wood block because the hole was not drilled properly, to line up with the big gear so i had to offset the second motor a bit, to make it work properly.)
Step 13: Motor Wiring
First, find the positive and negative terminals of both motors.
Then, connect them in series with wires, to get as much volts as possible. (positive end of 1 motor connected to the negative end of the other)
After that, solder a wire to the remaining terminals.
Then, solder the wires to long screws.
Lastly, hot glued the crews onto the frame. (one is glued longer then the other to differentiate from the + and - terminals)
Step 14: Possible Improvements
If I were to completely restart this project this is what I would have done differently
- Designed it on a 3-D design software (medium difficulty)
- Better gear ratios - make better gears using a 3-D printer and figure out best gear ratios (hard difficulty)
- Buy more efficient motors designed to generate electricity (more expensive) (easy difficulty)
- Use lighter materials for the rods - materials include: Aluminum, fiberglass, carbon fiber, titanium (more expensive) (easy difficulty)
- More compact design (medium difficulty)
- More motors (easy difficulty)