S-and-Drive Square Duct · Clamping
Clamp square duct before driving
Joint alignment
Task typeClamping
Tools / equipmentC-clamps, locking pliers, square
Before you start
- Confirm the sections are correctly sized and close enough to align without excessive force.
- Select clamps that will not crush the side walls or finish.
- Support both sections before clamping.
Lay it out
- Check the bottom plane, side walls, and diagonals before tightening clamps.
- Place clamps near strong folded edges or corners—not in broad unsupported panel centers.
Set and support it
- Level the sections on their supports.
- Bring corners together by hand first.
- Apply clamp pressure gradually and evenly.
Make the connection
- 1
Engage the top and bottom S-cleats.
- 2
Place clamps at the open side or corners.
- 3
Tighten only enough to bring the lock edges together.
- 4
Verify the duct is still square.
- 5
Start and seat the drives.
- 6
Remove clamps one at a time and recheck the joint before sealing.
Check the install
- The joint remains aligned after clamps are removed.
- No clamp dent or crease is visible.
- All locks are fully engaged.
- The duct plane and dimensions are maintained.
Common mistakes
- Clamping a wrong-size joint until it appears closed.
- Placing clamps in the middle of thin panels.
- Removing all clamps before the drives are seated.
- Failing to recheck square after tightening.
Stop and ask
Stop if clamp pressure distorts the duct, alignment cannot be held without the clamp, or the lock edges do not match.