Cantilever Tower Project

• 10.0 grams or less

• Minimum arm height: 10.0 cm

• Minimum arm length 10.0 cm

Cantilevered Towers are cranes

There must be a base

The base rests on the table

There are two armsOne arm is the CANTILEVERED ARM

This arm holds the 200 gram mass

There are two armsThe other arm holds the 500 gram

counterweight

There seems to be two basic styles of cantilevered towers

The Tall Crane and the Vee Crane

Glue, sewing thread and any type of wooden toothpick may be used

Remember, thread is your friend!

Toothpicks come in many shapes

10.0 grams uses about 150 flat toothpicks. These are weak and vary

a lot in quality

Larger and thicker toothpicks weigh more, but are harder to break.

It is okay to mix the types of toothpicks

Glue is IMPORTANT

• Do NOT use hot glue– Hot glue is too flexible and heavy– Joints will flex – The tower and arms will bend– The tower will weigh more than 10.0 grams– You will be VERY UNHAPPY

White or Wood Glue• Easy to use

• Soaks into the wood

• Holds very well

• Easy to clean up

• Does not need ventilation during use

• Does not dry quickly

Superglues • Dries quickly - much faster on flesh

than on wood

• Does NOT soak into wood

• Accelerator - catalyst to INSTANTLY harden the superglue

• Sticks to wax paper and plans

Epoxies• Avoid using epoxies

• Heavy after drying

• Must mix in the proper ratio

• Does not dry fast

• Does not soak into wood

ARM HEIGHT - is measured with a ruler on a right triangle.

ARM HEIGHT - is measured to the lowest part of the arm above the center of the 200 gram mass

ARM LENGTH - is measured from the front of the base to the point under the

center of the 200 gram mass

Thread Story

Do you know why you pull a rope across a street?

Well - have you ever tried to push a rope across a street?

Thread works well under tension forces

Tension forces pull

things apart

Tension Forces

Thread does NOT work well under compressional forces

Compressional forces PUSH things apart

Thread is your FRIEND!

• Sewing thread is light and strong

•Thread works well under tension

•Thread does not work well under compression forces

•Thread is light and does NOT add a lot of mass!

Rectangles and squares easily deform under pressure. This does

NOT make a strong and well-constructed tower.

Tower

Force

The tower will lean to the right or the left. Once leaning starts,

breaking soon occurs

Tower

Force

Triangles make for strong towers

The more triangles, the stronger the tower

Triangles strengthen towers by keeping the tower rigid.

The diagonal prevents the deformation of the shape

The more triangles, the stronger the

shape. This is true for both vertical and

horizontal parts of the tower.

Time to Build

No matter how much time you plan on, you will need more than you think.

Plan on several hours to draw plans, revise then build a tower.

Building Supplies

• Cardboard

• Wax Paper

• Sewing Pins

• Tape

• Fingernail Clippers or

• Diagonal Cutters

Cardboard

Use corrugated cardboard to build upon.

The pins easily stick into the cardboard..

The entire set up may be easily picked up, moved and stored.

Add photo of cardboard with pins sticking out of it

Plans

Draw plans the actual size the tower will be

Use a ruler to draw straight lines

Avoid making spans larger than the toothpicks to be used in building

Insert photo of drawing plans with a ruler

Include photo showing toothpick and spans smaller than a toothpick

Place the plans on the cardboard.

Tape the plans down so the plans cannot move.

Cover the plans with wax paper to protect the plans from glue.

Tape the plans onto the cardboard

Place wax paper over the plans

Place toothpicks over the plans

Use pins to hold the toothpicks in place until the glue dries.

When the side is finished, take out all the pins and remove the side from the wax paper.

Put glue on a toothpick and add it to the plans.

Place toothpicks on the plans

Use nail clippers or diagonal wire cutters to cut toothpicks

to the correct length

Put glue on toothpicks to be added to the tower

Use pins to hold the toothpicks in place

Use a box to protect and carry the tower

If the tower breaks before it is tested, it

MUST be repaired or rebuilt for a grade to be

earned.

The diagrams, answers to the questions and the sign off sheet

should be turned in before leaving school the day the tower is due

Make the diagrams BEFORE testing the tower

(Just in case the tower breaks)

The Tower Project is worth 150 points, but more points than this

may be earnedTowers may be tested early

to help ensure a

good grade.

Don’t wait to start working!

Cantilever Tower Project

• 10.0 grams or less

• Minimum arm height: 10.0 cm

• Minimum arm length 10.0 cm