Assembly of the elements

The assembly of the elements is straight forward. Blue-tac the bottom piece to the work surface.Apply glue to the side beams of the bottom piece making sure not to glue up the blue-tac.
Stand the side pieces into the wet glue.
Use some sort of support to keep the side pieces standing up straight while the glue dries.

Assemble sides to bottom element

You may need to hold the side pieces for a short while to ensure they sit down straight into the glue. After a few minutes the glue will hold the pieces.
Position the top element over the sides to ensure the sides dry in the correct position. Remember you will want to glue the top element on soon so making sure it is lined up now will save a lot of struggling later.

Position the top element over the sides to get an idea of the final position.

Leave the glue to dry until the side pieces are supporting themselves. Keep the assembly blu-tac'd to the work surface.

The glue is dry enough when the side pieces support themselves.

Check along the side pieces to ensure it has remained square during the gluing.
If all is OK, you can remove the blu-tac.

Check the sides are square.

Lay the top element on the work surface and apply a line of glue along both edge beams.
Position the rest of the bridge, upside-down, on top of the top element.

Position the bridge assembly on top of the top element.

Ensure the sides sit tightly on top of the wet glue. Manipulate by hand as required.

Sit the sides into the wet glue.

Ensure the sides meet the top element along the full length of the glue joint. Press by hand as necessary. treat with care as the assembly is delicate.

Set side pieces into wet glue along full glue joint length.

Hold by hand until glue has gripped the joint. Allow to dry overnight.

finished spaghetti bridge assembly.

Cut a foam decking piece to act as a roadbed. Make sure it is a loose fit and can be easily removed so the full engineered structure can be made visible.

Engineered Bridge

Finished Bridge with foam roadbed

Finished Bridge with Roadbed

And thats it......an Engineered Spaghetti Bridge.........enjoy making your own.




Back to Part 4

Building the sides of the Bridge

Cut one length of 250 mm and one length of 200 mm spaghetti and place on the cutting mat 50 mm apart.The 200 mm length should be placed so it is 25mm in from each end of the 250 mm piece....i.e. the centres of both parts line up.Use tape or blu-tac to hold the parts in place.

Main supports for Side of Bridge

Cut nine lengths of spaghetti to 50 mm long to act as cross braces.

Cut nine lengths 50 mm long as cross braces

Start positioning the cross braces so they fill the space between the main supports. These should be positioned every 50 mm starting in from the end of the 250 mm long piece of spaghetti.

Start positioning the cross braces

Once in place tape the cross braces in position so they will not move during gluing.

Tape the cross braces in position so they can be glued.

Add a cross brace at the end of the 200 mm long support at the left and right hand ends.

Add cross brace at the end of the upper support piece on the left end

Add cross brace at the end of the upper support piece on the right end

Fit in the remainder of the cross braces so there are nine in total, one every 25mm spacing.

Fill in the remainder of the cross braces

Apply glue to the joints.Leave to dry overnight.

Glue up the joints.

Add the outside end diagonal parts and glue up.

Diagonal brace goes at the end of each side piece

Add the diagonal brace at the other end of the side pieces.

Add diagonal bracing at other end of side piece

Start to add the internal diagonal bracing inside each rectangle observing that the direction causes no parallel braces but forms triangles.

Insert diagonal braces in all rectangle spaces.

The finished side pieces should be completely braced and glued up. Leave overnight to dry.

Completed side piece with braces in all rectangular spaces.

Back to Part 3

Continue to Part 5

Building the Top Structure

STEP 2 - TOP STRUCTURE

Cut two lengths of spaghetti to 200mm long and tape to the work surface exactly like in step 1 for the bottom structure.

Cut two main support pieces to 200mm long and tape to work surface

Cut five cross braces to 50mm long and place between the two long support pieces so they form four squares 50mm a side. Glue up exactly like in step 1.

Apply cross pieces to form 50mm squares

Apply the diagonal cross pieces exactly like in step 1 and glue up. The finished part will look like the picture below.

Add the diagonal cross braces and glue up

To add strength, add two long pieces of spaghetti in parallel to the assembly, the same as for the bottom piece.

Add strengthening pieces parallel to the length of the assembly

Run glue in the centre of the pieces along the full length.

Glue up the assembly where possible avoiding any blu-tac or tape.

Allow part to dry.

Finished bottom piece glued on one side

Once dry, flip over and glue up the bottom face.

Flip over and glue up bottom face.

Back to Part 2

Continue to Part 4

Building the individual elements of the bridge

Basic elements of an Engineered Truss Bridge :

The spaghetti bridge is made up of the basic geometric shapes ...squares and triangles. If you look around you , these can be seen in many places.

Example of a Truss Bridge

The Bridge is made up of 4 elements
1   Bottom Structure
2   Top Structure
3   Left Side
4   Right side

STEP 1 - BOTTOM STRUCTURE

Cut two lengths of spaghetti to 250mm long and tape down to work surface with a 50mm spacing between them.

Main supports for Bottom Structure

Cut six pieces 50mm long to act as cross braces.

Six cross braces, each 50mm long

Align the cross braces starting at one end so they form five squares 50mm a side each.

Cross braces positioned roughly in place.

Once the position is OK, tape the cross braces to the work surface so they stay in place during the gluing operation.


Cross braces taped in position ready for gluing

Ensure the cross braces touch the 250mm long support pieces so that the glue joint can be tight.

Close up of cross braces touching the outer supports.

Pour some glue from the bottle into a small receptacle....an art pallet or old yogurt pot works well.

Pour some glue into a small tray for ease of application

A small amount of glue goes a long way so don't overfill the art pallet.

A small amount of glue is enough to go a loong way.

The glue can be applied by using a small paintbrush. Use an old one as it cannot be used for paint again after being used for glue. A small cocktail stick works just as well.

Apply the glue using an old paint brush...the smaller the better.

A small dap of glue should be applied to each joint.Let the glue seep into the joint. Run the brush down the sides a little but do not allow glue to stick the structure to the mat.

A small amount of glue at each joint will hold the assembly together.

If the sticky tape does not hold the spaghetti pieces well enough , additional support can be provided by using small blobs of blu-tac. Put it where-ever needed but not near a glue joint where it will get stuck to the assembly.

For additional support a small blob of blu-tac can be used.

Once the glue has dried a little and the joint has taken some strength, approx 1 hour, the diagonal braces can be added. Cut a length of spaghetti long enough to span the diagonal in the 50mm square...this will be about 71mm long.

Diagonal pieces add strength but need to be fitted into the corners well.

The ends of the piece should be shaped into an arrow point so they fit right into the corners of the square. This can be done with a sharp knife, a scalpel, a craft knife, etc.The better the fit into the corners of the square, the stronger the glue joint will be.

Continue through the squares with the end point of one diagonal being the start point of the next diagonal.Each diagonal piece needs to be a snug fit and should stay in the square even without glue. when all the diagonal braces are in place, the joints should be glued up as before.



Ensure diagonals are a tight fit and glue up.

Once the diagonals have dried a bit and the glue joints attained some strength, add the final diagonal in two short lengths. Each length going into the remaining corner and touching the existing diagonal at the centre point.

Apply the first half of the final diagonal so it touches in the centre of the existing diagonal

Adjust the second diagonal piece so it makes a straight line from corner to corner.

Complete the final diagonal and glue up.

When completed there will be a full set of five squares with full corner to corner diagonal bracing. The strength of the bracing will come from a tight fit for all pieces.

Full corner to corner diagonal bracing for maximum strength

Once the full assembly is dry overnight, remove all the tape and blu-tac and flip the assembly over. Apply glue to all joints from the unglued side and allow to dry.

Completed Bottom Structure...250mm long

Once the basic structure is dry it is a good idea to strengthen the main supports. This will add strength but also allow a better platform for attaching the side pieces. Cut two lengths of spaghetti the same length as the base piece. Place the lengths alongside the assembled unit so it lies parallel to the long support element.

Add two lengths in parallel to the long edges of the assembly

Position the additional lengths in place and hold in place with small pieces of blu-tac. stick the assembly to the cutting mat with tape to hold it flat.

Hold additional support elements in place with blu-tac pieces.

Put enough blu-tac blobs along the length so the pieces are in close contact along the full length. This will aid gluing and ensure a strong bond.

Push the additional pieces into close contact with the assembly.

 Run a string of glue all along the parts where possible , avoiding getting glue on the blu-tac.

Run glue along the centre contact area of the two long spaghetti pieces.

Allow to dry, then flip over and apply glue to the bottom side. Any spots where the glue was missed can be covered at this stage.

Back to Part 1

Continue to Part 3