NTS&B Suspension Bridge Construction Notes

The bridge is now finished. The first couple pictures are of the completed bridge. Pictures of the construction are below and in order of construction.

Measurements / Construction Notes:

• Main (Horizontal) cables were made from 1/8 in steel cables.
• Vertical cables are made of cotton embroidery thread which are fed through #2 13/16 inch long eyelets, wrapped around top cable and tied. The thread is sightly stretch, so holds in place very well. A dab of hot glue was applied to the threads on the steepest part of the cable to make sure it doesn't slip. Caution, do not use super glue, as it bonds the fibers of the thread, and the thread becomes totally brittle.
• Eyelets are deck spaced every 2 inches on the bridge deck, and start at 2 inch from edge of tower
• Tower is 17 1/2 inch tall from top of deck, and hangs down 1 3/4 inch below deck
• Deck to bottom of lower cross brace between towers is 9 inches, and 14 inches to bottom of upper cross brace.
• Deck is made of 1x12x8, and is app 12 1/2 ft long total
• Overall length of deck from first cord on first tower to last cord on last tower is 120 inches
• Towers are made of 2 1x2's shaved and shaped with a router. The inside one rests on the deck, and has a grove routed in it for the all thread support rod and wires for the blinking LEDS. The cross piece is screwed to the inside pieces. The outside pieces are longer, and hang below the deck.
• Bridge holds 1 O-27 and 1 GScale tracl
  

Initial 1x12 bridge deck with towers

Close up of inside of bridge tower

A template was used to approximate main cables shape. Curve was first plotted on computer, then points measured every 2 inches and marked on template. Screws were then placed at the selected points.

Template in place on bridge cable. Template was clamped in position on the main cables, then the verticals were tied at each screw location.

A cable clamp was used on each end of steel cable to control the tension.
A 1x2 with routed grove was used to hold cable in position.

Eyelets were screwed into bottom of deck at 2 inch intervals to hold verticals. The bridge deck was made from 2-8 foot boards, which were routed and overlapped in the middle for additional support as shown above.

Closeup of knots at top of cable

Tower with outside 1x2 attached.

Picture showing vertical mesurments of tower

Picture showing horizontal mesurments of deck