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Building a Balsa Bridge. Prepared by: Barry Sparrow and Sal Ienco Civil/Construction Sault College. Assemble Materials. You will need: Balsa wood Tape Cutting knife Clamps Books Math set Glue Cardboard Pins Sandpaper Pencil. Prepare a drawing layout on cardboard.
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Building a Balsa Bridge Prepared by: Barry Sparrow and Sal Ienco Civil/Construction Sault College
Assemble Materials You will need: Balsa wood Tape Cutting knife Clamps Books Math set Glue Cardboard Pins Sandpaper Pencil
Cut the balsa pieces • Cut accurately • Take your time • Be careful • Total length to be 450mm • Save your off cuts (scraps) Cutting Video
Check all of your cut pieces Cut both truss sides at the same time
Begin gluing the pieces Use tape to hold parts in place Use ‘white’ or carpenter’s glue Be sure to glue all contact faces
Gluing Be neat Use a damp cloth or tissue to clean up Pins can hold parts temporarily Use scraps as spacers
Final truss assembly Check the alignment Complete the truss gluing
Allow the glue to dry Gluing Video Use more tape to hold parts in place Use books or similar weights to hold in place until glue has dried (1-2 hours)
Remove books and tape Remove books Cut away tape and remove carefully
Truss complete Remove any pins and remaining tape Repeat process for side 2
Cut the bracing and cross members Now the truss sides can be assembled Measure and cut the cross members Make sure bridge is minimum width (40mm)
Assemble the two sides Glue top and bottom cross pieces in place Line up cross members with truss webbing
Bridge Assembly continued Use spacers or blocks to keep parts straight Sand and trim before gluing to ensure a good connection
Glue truss to cross members Once the connections have glue applied the truss can be put in place Apply glue ready for the top cross members Use tape to keep cross members in place
Apply top cross members Install top cross pieces Diagonal bracing installed later after glue had dried
Add weights and let glue dry... Books keep everything in place until glue sets Spacers keep sides straight up (vertical) Let dry for 1-2 hours
Install final cross pieces Use clamps where needed to install final cross pieces
Add pieces on truss ends To deal with compression forces, extra material is added at each truss end
Add gussets at corners Adding gussets at bottom corners increases the connection strength
Prepare cross bracing For this bridge, diagonal bracing material was made from ½ thickness pieces, cut along the length
Prepare endbracing Cut and assemble ½ thickness angled bracing These pieces are used on each end of the bridge to keep it from collapsing sideways Trim to size after they are in place and the glue has dried
Bracing at ends Install bracing Note gusset added at top cross member
Trim bracing After glue dries, bracing can be trimmed and sanded
Install top & bottom bracing Diagonal ‘X’ bracing is installed Cut to fit Use pins or tape to hold in place until glue dries
Bracing Install bracing on top as well as bottom of bridge Note extra gusset at support point
You’re done! Testing Video Bridge is complete Touch up lightly with sandpaper It’s ready for testing