A pipe clamp is a workshop clamping tool that uses a length of threaded or plain steel pipe as its main bar. Woodworkers use it to pull boards tightly together during glue-up, hold assemblies square, and apply pressure across wide panels. It matters because a strong, even clamp setup can turn separate boards into a flat, durable tabletop, shelf, door, or frame.
The same clamp heads can be moved to different pipe lengths, making the tool flexible and economical.
Key Facts
- A pipe clamp has two main heads: a fixed head and a sliding tail stop.
- Clamping pressure is created when the screw handle pushes the movable jaw against the workpiece.
- Clamp force depends on screw torque, thread friction, and jaw contact area.
- Pressure = Force / Area, or P = F / A.
- For panel glue-ups, clamps are often spaced about 15 cm to 30 cm apart depending on board thickness and stiffness.
- Alternating clamps above and below a panel helps reduce bowing during glue-up.
Vocabulary
- Pipe clamp
- A clamp that uses a steel pipe as its bar and adjustable clamp heads to hold workpieces together.
- Fixed head
- The clamp head that locks onto one end of the pipe and usually contains the screw handle and jaw.
- Sliding head
- The clamp head that moves along the pipe and grips it when clamping force is applied.
- Glue-up
- The process of joining pieces of wood with adhesive while holding them in position until the glue cures.
- Clamping pressure
- The compressive force per unit area applied by a clamp to the workpiece.
Common Mistakes to Avoid
- Overtightening the clamp, which can squeeze out too much glue and starve the joint of adhesive.
- Using too few clamps, which leaves gaps or uneven pressure along the glue line.
- Placing all clamps on one side of the boards, which can bend the panel into a curved shape as the glue dries.
- Letting metal pipe touch wet glue directly, which can stain wood or bond the workpiece to the clamp.
Practice Questions
- 1 A pipe clamp applies a force of 900 N through a jaw pad with an area of 0.003 m². What pressure does it apply to the wood?
- 2 A 120 cm long panel needs clamps spaced every 20 cm along its length. How many clamp positions are needed if one clamp is placed at each end?
- 3 During a tabletop glue-up, explain why a woodworker might place some pipe clamps below the boards and some above them instead of placing all clamps on the same side.