Turning Sheet Edges

For making flanges (a 90° bend ) or folds (180° bend), slot a block of wood and hold it in a vise while bending the sheet with the edge in the saw slot (Fig. 3-1) or use the forming block in your hands with the sheet against the top of the workbench as in Fig. 3-2.

Hemming Sheet

Notice that one edge of the forming block (Fig. 3—3) is cut back at an angle to allow bending the sheet past 90° (Fig. 3-4). This facilitates making folds, which then are completed easily by closing the bend with a hammer, using the block to prevent denting, as in Fig. 3-5. Folding over the edge of a sheet in this manner is often called "hemming," and the folded-down portion is known as a "hem."

The block is slotted to the desired depth on a bench saw. If this tool is not available, make a similar block by nailing two thinner ones together using washers to space them apart to provide the slot desired.

Bending Sheet

To make bends in center area of a large sheet, use C-clamps to hold two forming blocks against the metal (one on each side of sheet) at the point of bend (Fig. 3-6). Hold boards in hands, and force sheet against bench top to make bend. Hammer down on boards to sharpen the bend.

Long pieces of sheet should be clamped between boards of sufficient length to secure sheet tightly along entire length of bend. For sharp bend, hammer the edge while clamped over a sharp hardwood bending block.

To make a bend of unusual contour or to bend entirely around a board such as a window sill, clamp the metal over a form block and hammer with a rubber mallet or plastic-faced hammer to get the shape wanted.

Box Sections

When making a box from a single piece of sheet, the ends and sides are bent up, with flanges for locking the corners. To avoid interference when making the various bends, bend up the sides first, as in Fig. 3-6. Then cut scrap block just the length of the end. Clamp this to end section of box and bend up ends, as in Fig. 3-7. Remember to always bend up flanges and bend down folds before attempting to bend up sides and ends.

To prevent tearing of the metal at the intersection of the sides, ends, and bottom of the box section, drill a 1/32" or 1/16" diameter hole through the sheet at this intersection point.

Scallops

To create fluted edges or scallops around the edge of trays, coasters, and the like, bend up the edge at regular intervals with a slotted scrap of wood as in Fig. 3-8, or use the fingers to bend the edges down over a radiused block as in Fig. 3-9.

For a 4" diameter coaster, the fluting tool in Fig. 3-8 should have a notch 3/8" deep, and the block in Fig. 3-9 a 2" radius and a 2" portion of the circumference to obtain six uniform scallops. For other sizes of circles, make the block radius and portion of the circumference used equal to the radius of the circle.

Curling Sheet

Cut a slot entirely through a dowel rod or broom handle with a scroll saw as in Fig. 3-10 or cut slot halfway through rod with a circular saw. If the latter method is used, attach a C-clamp on the end of rod to get a secure grip on it while feeding to saw blade.

Insert the sheet edge to be curled into the slot, clamp in a vise, and bend as in Fig. 3-11. Or use a C-clamp to tighten sheet in the slot, and hold the sheet against the top of workbench while rotating slotted rod with your hands.

Fig. 3-10.

Bending Bar

Either 1/8" or 1/4" thick bar will bend easily if clamped securely in a mechanic's vise and hammered with a heavy rubber mallet while applying bending force with free hand. Cover vise jaws with scrap aluminum sheet to avoid marring bar.

For a sharp 90° bend on the inside of 1/4" bar where strength is not too important, notch the bar on a bench saw as shown in Fig. 3-12 before bending.

Forming Bar

To make small-diameter circles, hammer bar around a sturdy round object such as a large water pipe held in a vise (Fig. 3-13). The 1/8" x 3/4" bar is curved around tubing easily if firmly anchored to it first by a C-clamp as in Fig. 3-14.

Fig. 3-11.

A slot cut in the end of an iron pipe makes a good bending jig for rod or bar. Hold the pipe in a vise, and bend the rod or bar around the pipe by hand (see Fig. 3-15). To make a sharp bend, hammer in the vise. For a soft curve, bend around a pipe as in Fig. 3-16.

Multiple Bends

A dowel-rod jig (Fig. 3-17) is excellent for bending and forming the 1/8" x 3/4" bar where exact dimensions are desired with two or more bends involved. Such a jig is valuable where a number of pieces are to be formed exactly alike. The successive bends are made in the jig one at a time by inserting the dowels in sequence as the bending progresses.

Forming Scrolls

Cut plywood circles of size desired. Drill out a hole big enough to accommodate one end of a C-clamp.

Scrolls of any size are easily bent by hand from 1/8" x 3/4" bar using such form blocks and a C-clamp to anchor the end of the bar as in Fig. 3-18.

For bending the 1/4" x 1" bar, use hardwood form blocks, cut a 1" deep slot radially into circumference, and screw securely to bench top. Insert end of bar in this slot, and bend as in Fig. 3-19.