How to Form a Cone With Sheet Metal
Forming a cone out of sheet metal is the same process as forming a cone out of paper. The only difference is metal is a bit more difficult to cut and fasten. Therefore, you can practice on a piece of paper or poster-board to get the proper size and angle.
Cutting a Circle
Draw a circle on your piece of metal. The radius of the circle will end up being the slant length of the cone from tip to opening. Using your straight edge, draw a line for the radius from the center to the circumference. The opening of the cone will be somewhat adjustable.
Cut around the outside perimeter of the circle using your tin snips. You can use either straight or curved snips, whichever is easiest, because you will be throwing the outside away. You can bend the outside out of your way as you cut.
Cut inward along the radius line from the circumference to the center.
Overlap one side of the radius cut over the other. The tighter you wrap it, the smaller the opening of the cone will become.
Securing the Cone
Clamp the cone in place using the C-clamp or vice-grips to hold it at the size you need.
Drill several 1/8-inch holes along the radius line through the overlapping layers. The closer to the edge you make the holes, the less metal will end away from the cone.
Insert a pop-rivet through the hole in all the layers of metal. Using the pop-rivet gun, squeeze the rivet until the stem snaps off. Repeat for all the holes.
Things You Will Need
- Tin snips
- Sheet metal
- Permanent marker
- Compass or circle to trace
- Drill motor
- 1/8-inch Drill Bits
- Pop rivet gun and rivets
- C-clamp or vice-grips
- If you touch one point of the circle you draw on the metal to the edge, you will have a built-in starting point for your cut. Cutting a small circle in the center of your circle before twisting it into a cone will make it into a funnel.
- You may want to cover the cut edges with foil tape or duct tape to prevent cuts.
- Sheet metal is extremely sharp; you should always wear gloves and eye protection when handling it. Also, watch out for metal splinters.