Everything you need to build this bridge by hand: a full-size plan, the cut list, the joints and the glue order.
Build pack · UCF Mission: STEM Balsa Bridge Contest 2025-26
Loads (simulated, not yet checked on real breaks)
Expected to break first: member crushing/buckling, at SG2 (stringer).
One truss seen from the side, 16 in long. Both trusses are built on this same plan. The plan prints full size across the pages outlined below: trim each page along its dashed line, lay it over the page to its left or above, line up the ⊕ marks and tape it. Print at 100% (“Actual size”) and check the scale bar on each page with a ruler.
Every piece, labelled as on the plan. Lengths are the finished long edge, to the nearest 1/16 in. Angles are between the cut and the stick's edge (90° is square), left end first as drawn (bottom end first for verticals); where an end has two cuts, both are given. For the truss pieces, lay the stick on the full-size plan and mark the cuts from it.
| Piece | What | Cut | Stick | Length, in | Ends |
|---|---|---|---|---|---|
| B1 | bottom chord | 4 | 1/16 × 1/16 in | 4 11/16(4.67) | both square |
| B2 | bottom chord | 4 | 1/16 × 1/16 in | 3 5/8(3.60) | both square |
| B3 | bottom chord | 4 | 1/16 × 1/16 in | 2 9/16(2.55) | both square |
| B4 | bottom chord | 4 | 1/16 × 1/16 in | 5 3/16(5.19) |
Every kind of joint on the bridge, once, enlarged. Blue runs through; amber is cut to fit against it. Truss joints are seen from the side, like the plan; joints between the trusses are seen from above.
Pieces that run through a joint go down first, because the others are cut to fit against them: the chords (and the end posts, where they run through the corner). Then the webs between them. Build the second truss the same way on the same plan. The pieces that join the two trusses go in last: the deck members first, then the bracing above them.
First truss: chords
B1, B2, B3, B4, T1, T2
Pin them down on the plan over wax paper or plastic wrap.
First truss: webs
E1, E2, V1, V2, V3, D1, D2
Cut each end to the plan, then glue it against the chords.
Second truss: chords
B1, B2, B3, B4, T1, T2
On the same plan, once the first truss is dry and lifted off.
Second truss: webs
E1, E2, V1, V2, V3, D1, D2
The same pieces again.
Join the trusses: deck
FB1, FB2, FB3, SG1, SG2, SG3, SG4
Our summary of the UCF Mission: STEM Balsa Bridge Contest 2025-26 rules. If anything here disagrees with the rulebook or the organizer, they win.
These print one per page at full size. On screen they show at your display's scale.
Page A1 of 2 · sandwich howe-4 for UCF Mission: STEM Balsa Bridge Contest 2025-26
Full size. Row A, column 1.
2 Letter pages, landscape, at the end of this pack.
| both square |
| D1 | diagonal | 2 | 1/16 × 1/16 in | 6 9/16(6.54) | 32° / 33° |
| D2 | diagonal | 2 | 1/16 × 1/16 in | 6 1/8(6.11) | 25° / 29° |
| E1 | end post | 2 | 1/16 × 1/16 in | 6 3/4(6.76) | 56° / 34° |
| E2 | end post | 2 | 1/16 × 1/16 in | 6 7/8(6.85) | 39° / 54° |
| FB1 | floor beam | 1 | 1/16 × 1/16 in | 2 1/8(2.15) | both square |
| FB2 | floor beam | 1 | 1/16 × 1/16 in | 2 1/8(2.15) | both square |
| FB3 | floor beam | 1 | 1/16 × 1/16 in | 2 1/8(2.15) | both square |
| SG1 | stringer | 1 | 1/16 × 1/16 in | 3 5/8(3.60) | both square |
| SG2 | stringer | 1 | 1/16 × 1/16 in | 3 5/8(3.60) | both square |
| SG3 | stringer | 1 | 1/16 × 1/16 in | 2 9/16(2.55) | both square |
| SG4 | stringer | 1 | 1/16 × 1/16 in | 2 9/16(2.55) | both square |
| ST1 | strut | 1 | 1/16 × 1/16 in | 1 15/16(1.96) | both square |
| ST2 | strut | 1 | 1/16 × 1/16 in | 1 15/16(1.96) | both square |
| T1 | top chord | 4 | 1/16 × 1/16 in | 3 9/16(3.55) | both square |
| T2 | top chord | 4 | 1/16 × 1/16 in | 3(3.00) | both square |
| V1 | vertical | 2 | 1/16 × 1/16 in | 5 5/8(5.60) | both square |
| V2 | vertical | 2 | 1/16 × 1/16 in | 5 5/8(5.60) | both square |
| V3 | vertical | 2 | 1/16 × 1/16 in | 5 5/8(5.61) | 87° / 87° |
6 sticks, 36 in long, with 1/32 in for each saw cut.
Stick 1 · 1/16 × 1/16 in · 0.1 in left over
E2 ×2, E1 ×2, D1, ST1
Stick 2 · 1/16 × 1/16 in · 0.2 in left over
D1, D2 ×2, V3 ×2, V2
Stick 3 · 1/16 × 1/16 in · 0.4 in left over
V2, V1 ×2, B4 ×3, T2
Stick 4 · 1/16 × 1/16 in · 1.1 in left over
B4, B1 ×4, B2 ×3
Stick 5 · 1/16 × 1/16 in · 1.7 in left over
B2, SG1, SG2, T1 ×4, T2 ×3
Stick 6 · 1/16 × 1/16 in · 12.0 in left over
B3 ×4, SG3, SG4, FB1, FB2, FB3, ST2
Stand the trusses up square, the right width apart.
Join the trusses: bracing
ST1, ST2
Check the bridge is square before the glue sets.
Page A2 of 2 · sandwich howe-4 for UCF Mission: STEM Balsa Bridge Contest 2025-26
Full size. Row A, column 2. Trim the left edge on the dashed line.