Turning a Bar Clamp into a Circle‑Drawing Compass

Need to draw a large, precise circle without buying a dedicated trammel? A standard bar clamp can handle the job with a few simple adjustments. Here’s a step-by-step guide for your weekend workshop.

Materials Needed:

• A bar clamp (any size that covers your desired circle radius)
  
  
• Pencil or marker
  
  
• Nail or screw for the centre point
  
  
• Measuring tape or ruler
  
  

Step 1: Set the Centre Point

1. Decide where the centre of your circle will be.
   
   
2. Drive a nail or screw into that spot. This will act as the pivot point.
   
   

Step 2: Attach the Bar Clamp

1. Place the fixed jaw of the bar clamp over the nail.
   
   
2. Ensure the clamp can swing freely around the nail without obstruction.

Step 3: Position the Pencil

1. Place your pencil in line with the movable jaw along the bar.
   
   
2. Adjust the pencil’s distance from the nail to match the desired radius of your circle.
   
   
3. Tighten or lock the movable jaw so the pencil stays in place.
   

Step 4: Draw the Circle

1. Hold the centre point (nail) steady with one hand.
   
   
2. Swing the pencil around the pivot, keeping it perpendicular to the surface.
   
   
3. Complete a smooth, full circle without lifting the pencil.
   
   

Step 5: Finishing Up

1. Release the clamp and remove the pencil.
   
   
2. Your circle is now perfectly sized for cutting, routing, or marking layouts.
   
   
3. For larger projects, repeat the process, adjusting the radius as needed.
   
   

Bonus Tips:

• Double‑check radius: Use a tape measure to confirm the pencil distance from the centre.
  
  
• Clamp stability: Make sure the nail is secure, or the circle may wobble.
  
  
• Alternative pivot: If you don’t want to drive a nail, a temporary tack or small block with a hole works just as well.
  
  

This trick shows how a standard bar clamp can become more than just a holding tool. By turning it into a compass, you save money, reduce tool clutter, and discover clever uses for what you already own. With practice, it becomes a reliable technique for circles of almost any size in your workshop.