BBidSimp

BIDSIMP ARCADE · ACT CEILINGS

Square the Grid

Read the diagonals. Make the call. Move the front main.

Personal best 0

Seconds60
Score0
Correct0
Streak0

Which way should the front main move?

A Front right to back left32 5/8″
B Front left to back right32 5/8″
ACT grid opening, top viewA square reference diagram. The back main is fixed at the top. The front main at the bottom can move left or right. Orange diagonal A connects back left to front right. Teal diagonal B connects back right to front left. Read the measurements above; the drawing never shows the offset. BACK MAIN · FIXED A B FRONT MAIN · MOVABLE

Drawing stays square. Use the tape readings.

Ready for a quick challenge?

10 points per correct answer. Keep going after mistakes.

Tap a choice or use L, S and R. Tab and Enter also work.

Check the opening, not just the drawing.

A ceiling bay can look square from a baker scaffold while its diagonals tell a different story. Checking both diagonals helps installers catch a small rack before it affects panel fit and grid alignment.

Use the same inside corners.

This exercise uses a nominal 2′ × 2′ bay with 15/16″ grid faces. At square, the clear inside-flange opening is 23 1/16″ × 23 1/16″. Its diagonal is about 32 5/8″. Readings are rounded to the nearest 1/16″. Centerline measurements would be different.

Keep one main fixed.

The back main stays fixed. If A, from front right to back left, is longer, move the front main left. If B, from front left to back right, is longer, move it right. That shortens the longer diagonal and lengthens the shorter one.

Equal readings need the right assumptions.

In this model, opposite runners stay parallel, tee lengths stay equal and the bay stays in one plane. Equal diagonals then identify the square condition. A real opening can have other problems, and tape rounding can hide a tiny difference. Check spacing, level and connections too. This game only offers equal readings for a truly square simulated bay.

Move a little. Measure again.

The diagonal difference is not the distance to move the main. A diagonal changes at an angle to that movement, and both diagonals change together. Make a small adjustment, then recheck both measurements.

Grid dimensions: Armstrong Prelude XL 15/16″ cross tee. This independent practice game is not a manufacturer installation specification.