US Mid-South · Balsa sticks, 1/16 to 1/4 in
48 in gap · a steel tube on top at mid-span · no mass limit
Official rules (PDF)(opens in a new tab)The rules don't mention AI tools. Check with your teacher or the organizer before you enter a design from this site.
Read it in the rulebook(opens in a new tab)Soon this page will show ready-made designs for this contest, each checked against every rule below, loaded until it breaks, and buildable with a hobby knife, with a printable build pack. For now, here are the rules in plain words.
Our summary of the official rules. If anything here disagrees with the rulebook or the organizer, they win.
Where a rule can be read two ways we use the reading the organizer most likely meant and show the other. Where ours is the looser one, ask your organizer before you rely on it.
'Lamination' means coating members with glue; built-up members up to 0.75 in are allowed (that is why a 0.75 in member limit exists alongside 0.25 in pieces).
The other reading: Members must be single pieces.
The 'base' is the bearing chord plus the deck system on it; together at most 0.75 in deep.
The other reading: The bearing chord alone.
The all-thread needs a 1/2 in clear hole on the centreline; the tube is long enough to rest across both top chords.
“must span 48 inches and be no longer than 52 inches”
“Width ... is limited to 7 inches”
“Maximum height ... 10 inches (from lowest part to highest part)”
“no larger than 0.25 inch by 0.25 inch by 15 inches”
“members ... no thicker than 0.75 of an inch”
“base ... no thicker than 0.75 of an inch, from top to bottom”
“commonly referred to as crazy glue containing cyanoacrylate”
“Lamination of the bridge is not allowed”
“must utilize trusses or arches ... beam bridges are not allowed”
“Other than the two ends, no part of the bridge may touch the tables”
The other reading: A smaller rod (3/8 in) or a shorter tube.
No member may be longer than one 15 in piece; longer chords are made per panel.
The other reading: Spliced chords.