lady kate
Printer paper (4 sheets)
Masking tape (unlimited)
Standard rubber bands (2)
Tongue depressor or popsicle sticks (2)
Zip ties (6)
Your assignment is to build a catapult which can propel a marble the maximum distance.
HOWEVER, be careful..... there is also an accuracy condition (and a
multiplier.....see below). ADDITIONALLY, your distance (inches) will be divided by the weight (ounces) of the structure to give a final performance number. Please also account for all of the materials that you use. I would like you to also include a procedure for building this just in case I want to build one at some point in the future. You will also be subjected to an additional multiplier based on the consistency of performance (huh??).....let me explain:
You must land the marble in the basket 3 times in order for the distance to count
If you land the marble 3 times in 10 tries, the multiplier is 1; 3/20 the
multiplier is
0.8, 3/30 is 0.6, 3/40 is 0.4, 3/50 is 0.2, 3/60.....give-up, you are defeated
DESIGN OF A catapult
A crossbow (catapult) is a weapon that has a level bow mounted on a stick, called a stock. It shoots projectiles, called bolts, at a target. Present day crossbows are compound crossbows which have stiffer appendages to make the bow more vitality effective and a string joined to a pulley framework to make it less demanding to move back with expanded power as the bolt is let go. The pulley framework likewise guarantees a smooth release of the bolt. (I cannot use any of this because my project was to build a catapult not a crossbow)
Your assignment is to build a catapult which can propel a marble the maximum distance. HOWEVER, be careful..... there is also an accuracy condition (and a multiplier.....see below). ADDITIONALLY, your distance (inches) will be divided by the weight (ounces) of the structure to give a final performance number. Please also account for all of the materials that you use. I would like you to also include a procedure for building this just in case I want to build one at some point in the future. You will also be subjected to an additional multiplier based on the consistency of performance (huh??).....let me explain:
· You must land the marble in the basket 3 times in order for the distance to count
· If you land the marble 3 times in 10 tries, the multiplier is 1; 3/20 the
multiplier is 0.8, 3/30 is 0.6, 3/40 is 0.4, 3/50 is 0.2, 3/60.....give-up, you are defeated (that is what the assignment form my professor was to build I just need a wright up of how to build a catapult I alred built one using only what I was allowed in the directions
The materials required to design the crossbow are: 2 long pieces of pine wood about 1 meter each, a thin piece of pine wood about 6cm long and 1cm thick, 1 meter long PVC pipe 3cm in diameter, duct tape, 4 wood screws, 1 wood nail, 2 small steel pulleys, nylon string, 6 heavy duty tie clips, PVC glue, a square piece of foam, wood stain and 6 pieces of thin dowel.
The tools required for this project are: Wood rasp, ball point hammer, pencil, hand saw, hack saw, sandpaper, bench clamp, power drill and a chisel.
Printer paper (4 sheets)
Masking tape (unlimited)
Standard rubber bands (2)
Tongue depressor or popsicle sticks (2)
Zip ties (6)
(Above are the materials that I’m allowed to use)
So due to the nature of this assignment I cannot use the stuff below you can save as much as you want to from it but it all need to be changed because I did not build a crossbow so that is why it all need to be changed but if you wanna keep the format that is fine with me)
Steps:
Part 1: Building the body
Find an agreeable length for the stock which ought not go over a meter and stamp the wood where you need to cut it. Use a hand saw to cut the wood on the mark you made for the length of the stock.
Mark the area for a trigger by drawing an adjusted rectangle shape on top of the pine wood. Using a chisel, drill and wood rasp, carefully gouge out the rectangle out of the wood. Then use a sandpaper to smoothen the area around the hole.
Use a chisel to make 1/8 inch groove close to the front of the trigger opening and sand it after it is cut. This groove will hold the string.
Make the groove that holds the dart by denoting the focal point of the finish of the wood, most distant from the string score and after that denoting the focal point of the finish of the rectangle opening, most distant from the string groove. Draw a straight line between the two stamps then utilize a bore, etch, and mallet to cut a ¼ inch profound channel along the checked line. Sand the depression until totally smooth.
Use a second piece of pinewood to make the grip to hold when shooting. Cut the wood to be around 8 inches long then use PVC glue to attach it to the bottom of the stock. Leave the glue to dry.
Use wood stain to ensure wood will be protected from the elements then apply the sealer.
Part 2: Making the bow
Use a hacksaw to cut the PVC pipe into a 36 inch length
Use a hacksaw to cut a small groove to fit a small wood screw at each end of the PVC.
Attach pulleys to both ends of the PVC bow, and the string will feed through them. Insert a small wood screw on both ends of the PVC pipe and then attach the pulleys to the wood screws on either end of the pipe using wire ties.
For the crossbow to be able to fire, the nylon string needs to be threaded through both pulleys correctly. Securely tie one end of the nylon string to the wood screw on the left side of the PVC pipe. Bring the string across to the pulley on the right end of the PVC pipe, and loop it in and around the pulley then bring the string back to the left side and loop the string in and around the pulley on the left.
Finally, bring the string back to the right and tie it securely to the right wood screw.
The string should run across the PVC pipe three times.
Pull on the string coming out of the pulleys. The PVC pipe should flex like a bow.
If the pipe does not bend slightly like a bow would, pull the thread out and start again.
Part 3: Attaching the bow to the stock
Create a groove for the bow on the end of the stock
Use a wood rasp too carve out a rounded groove wide enough to fit the pipe on the end of the wood stock.
The groove needs to be deep enough to fit the PVC pipe securely and have room to move around.
The bow needs to be secured to the stock to ensure proper use. Strings need to be in the correct place for the crossbow to be effective. Use duct tape to secure the PVC pipe to the stock by wrapping it around the pipe and the end of the wood stock.
Test the bow to ensure the strings are in the right place.
Part 4: Building the trigger system
Use a thinner piece of pine wood to create the trigger system.
Draw an L-shape on the wood.
The small portion of the “L” shape should be slightly smaller than the box you carved in the stock.
Cut the L-shape out of the wood with a saw. This L-shaped piece of wood will be the trigger.
Sand it until it is smooth.
Use a chisel to carve about a ⅛ inch channel across the short part of the L-shaped wood.
A hole should be drilled down by the corner of the L, but centered in the wood. It should be big enough to fit the nail you are using to attach it to the stock.
Attach the trigger onto the stock so that it will pop the string out of the groove when pulled.
Put the L-shaped trigger in the rectangle hole with the groove facing upwards and the L pointing forward. Use a hammer to push a nail through the stock and hold the L-shaped trigger in place at the angle.
Use sand paper to fine tune the trigger until the action is smooth
Part 5: Building the Handle and Butt
The handle steadies the crossbow so you can pull the trigger. Use pine wood to cut a 20 cm length to be used as the handle and sand it into the rough shape of a handle.
Attach the handle to the stock so you can easily fire the crossbow. Use PVC to attach the handle to the stock and wait. When the glue is dry, use a hammer to drive a few nails into the handle to firmly secure it on the stock.
Use a crossbow by pressing the butt against your shoulder, so padding the butt of the crossbow will make it more comfortable.
Secure foam around the end of the stock that is placed on your shoulder with duct tape.
Part 6: Testing
Set up a target where you are going to fire but make sure it is safe. The crossbow should shoot bolts around 65 to 100 feet.
(all of this need to be aligned with what the assignment was to build and only using the materials that were allowed)
