How to Make a Metal Stair Railing
Most steel railings are made of vertical bars welded to a frame of crosspieces and posts. The crosspieces may form a parallelogram following the angle of a stairway, or they may form a rectangle along the edge of a porch. An ornamental strip of molded cap rail typically tops this frame. You can join a series of frames to several posts to make a long railing.
Whatever the configuration of a railing, the bars usually are solid steel ½-inch square. Get posts of 11-gauge steel tubing 1-inch square or — for extra strength — of solid steel 1-inch square. Traditionally, you'll use crosspieces of 1-inch channel iron punched with square holes for the bars. You'll weld the molded cap rail onto the top channel. However, you can save time and money by using a cap rail with the top channel already molded into it. Flanges parallel to the edges of the cap rail anchor the bars in place for welding.
Before making a railing for either a stairway or a porch, check the building-code requirements where you live. Use these as the basis for planning the railing and ordering materials.
When you order materials, ask the supplier to cut the steel to length. The cap rail should equal the length of the railing, plus 5 inches for each decorative curve at the ends — 6 inches if the curve is at the bottom of a stair railing. For a railing like the one shown here, determine the length (excluding the curves) by measuring from the edge of the top step to the edge of the bottom step and adding 2 inches for the two posts. Use this figure for the channel as well, and then make adjustments during construction.
To find the height of the bars, add ½ inch to the distance from the lower channel to the bottom step, and subtract this sum from the railing height; the location of the lower channel and the height of the railing are usually set by code. The length of the posts will depend on how you anchor to the stair or porch. If you set into holes drilled in concrete, they should equal the railing height plus 4 inches. However, if the porch or stairway is concrete covered with a brick veneer, add 3 more inches to allow the post to pass through the veneer and into the concrete below. If the porch or stairway is of concrete shallower than 4 inches, order posts that equal the height of the railing, and anchor them with post flanges and lag bolts.
Ask the steel supplier to prepunch the channel to hold the bars. An interval of 6 inches, center to center, satisfies most building codes. For a diagonal railing, the holes must be slightly rectangular — ½ inch wide and â…? inch long. If the supplier cannot prepunch and shear the steel, cut it yourself with a hacksaw, then drill and file the holes.
Once the metalworking materials are at hand, draft a full-scale template for the metal railing on a 4-by-8-foot sheet of ½ inch plywood. Because one edge of the plywood serves as a reference for all the measurements, that edge must be smooth and the corners square.
To make the butt welds and fillet welds that hold the railing together, you also need a supply of E6013 electrodes â…› inch in diameter. Once you have made the welds, grind the butt welds smooth, coat the railing with rustproof primer, and finish it with black exterior enamel made for metal surfaces.
Before you begin welding, be sure you thoroughly read, understand, and follow the Safety Rules for Welding.
It is essential to dress yourself properly and maintain a hazard-free workshop. When bending metal with oxyacetylene equipment you must, as when welding, wear a tinted welding face mask or tinted welding goggles to protect your eyes from sparks and glare. You will also need insulated welding gloves, welding jacket, and a shop apron or coveralls.
Making Straight Cuts with a Hacksaw
Cutting Across a Narrow Strip
Clamp the metal stock in a vise with the scribed cutting line running vertically, and close to the jaws of the vise. Place the hacksaw blade on the waste side of the line and pull lightly across the metal until the blade bites into the edge. Then, using both hands to steady and guide the saw, cut along the line. Apply light, even pressure on the forward stroke and no pressure on the return. Let the blade do the work. Do not try to saw too deeply with each stroke. Near the end of the cut, support the waste metal with one hand to keep it from binding. Free the waste metal with a few last, short cutting strokes.
Cutting Along a Lengthwise Edge
Clamp the metal stock in a vise as for a crosswise cut, with the cutting line running vertically. Turn the saw blade perpendicular to the handle of the saw and keep the saw frame horizontal. In this position the frame won't get in the way as the cut deepens. Begin the cut as for the crosswise cut, and again support the waste metal with one hand when you near the end of the cut.
Making Symmetrical Twists in Cold Straps
Using Pipe Wrenches for Leverage
Cut a strap or rod at least 1 inch longer than the desired finished length. Clamp one end in the vise. Then form a twist handle on the free end with two large pipe wrenches tightly clamped to the metal so that they project in opposite directions, perpendicular to the strap. To protect the metal from scratches, pad it with masking tape before tightening the wrench jaws.
Slowly rotate the wrenches until the twists develop along the length of the metal. The twists will be evenly spaced. Use a hacksaw to cut the metal to the exact length needed.
A Curve to Finish the End of a Metal Railing
Lay Out an Iron Scroll
To lay out a strap-iron scroll, first make a baseline that will form the largest diameter of the scroll design. Find the midpoint of the baseline and use a compass (or a nail, string, and pencil) to draw a semicircle. Then find the midpoint of the semicircle's radius and continue the scroll line with a second semicircle, making it half the size of the first. Continue to add semicircles of decreasing size until you have the number of turns you want in the scroll.
Enlarge a Small Sketch
Using a sheet of ¼-inch grid paper, draw a small sketch of the metal shape you are planning. Measure the longest dimension of the form you have sketched, and divide this number into the longest dimension desired for the enlarged sketch. This gives the multiple of the large sketch as compared with the small. Multiply this figure by ¼ inch to get the size of the grid squares needed for the larger sketch. Lay out the large grid on a piece of heavy wrapping paper, and transfer the small sketch to the large grid by redrawing each section of the small sketch, box by box, on the corresponding squares on the large grid. Then smooth out the curves of the large pattern using a broad-tipped felt marking pen.
Finish a Metal Scroll
To bend the end of a metal strap into a scroll shape, clamp a special scroll-bending jig in a vise and slide the strap between the pins of the jig. The pins should be placed in holes close to the strap. Feed the strap through the jig, bending the strap to match the scroll shape on your template.
You can make your own scroll-bending jig by bending a â…œ-inch mild-steel rod into a U shape. To do this, first bend the metal rod ends at an acute angle, then finish the bend by squeezing the legs of the U shape in a vise. Leave a space between the legs equal to the thickness of the metal strap you will bend. Cut excess metal rod from the jig with a hacksaw. The jig ends should protrude 1¼ inches above the strap when 1 inch of the U-shaped end is clamped in the vise.
With a torch and a simple welding bending tool, it's not difficult to make a smooth bend, for example, the curve that finishes the end of a stair railing. Follow these steps to create ornate hand-cut metal curves and metal scrolls.
Marking and Heating the Stock
Mark the metal where the curve will start, clamp the piece in a vise, and light the torch, setting it for a neutral flame. Starting at the one end of the line, move the flame across the metal, down one edge, across the end, and up the other edge to the line. Repeat this pattern with the torch until the entire section glows bright orange. Turn off the torch and set it aside.
Turning the Curve
With a welding bending tool, grip the hot metal about ¼ inch from the end and turn it down into a curve (inset), using the same motion though on a larger scale that you would use if you were starting to open a tin can with a key. Sight along the top of the stock to see if the bend is uniform. If it is not, use the side of the bending tool to pound the metal into line while it is still hot. Brush the scale off the metal with a wire brush.
Forming a Curve in Metal
Cut a section of strap or rod to the length needed for the finished piece of metal. To determine this length, bend a wire along the contours of the paper template, then straighten the wire and measure it. Using the template, find where the curve will start and end, and then mark these points on the metal work piece with a pencil.
Clamp the metal work in a vise between a vise jaw and a pipe that has an outside diameter that measures about the same as that of the inside diameter of the curve. Then bend the metal toward you until the shape of the metal matches the template. For a longer, gentler curve, bend the metal in several places in succession, feeding the metal farther down into the vise for each bend you make.
Bending Steel with a Torch
Although you can bend soft or thin metals cold, you must heat thick pieces of steel to make them malleable. An oxyacetylene torch provides the necessary heat. Fit the torch with a welding tip that distributes the flame evenly over the area you need to bend. The best tip for the job is a special heating tip called a rosebud, which has six flame-spreading orifices. You can also use a standard welding tip that is large enough to weld metal ¼ inch thick — most manufacturers label it a No. 5 tip. Or you can use a No. 3 or No. 7 tip.
Welding the Framework
Lay the metal posts, channel, and cap rail in their positions on the template. To transfer the position for the bars from the channel to the cap rail, slide the channel up against the cap rail and mark through the holes in the channel onto the cap rail. Then lay the channel back in position. With the arc welder set for 100 amps, butt-weld both ends of the channel to the posts, adjusting the current, if necessary, to make a good weld bead.
Prop up the channel and posts on scrap metal so that the ends of the posts butt squarely against the cap rail, then butt-weld the upper edges of the posts to the cap-rail flange. Make fillet welds at the tops of the posts. Turn the frame over, and weld along the opposite sides of channel, posts, and cap rail.
Welding the Bars for the Stair Railing
Have a helper hold the framework steady, upside down on the cap rail. Insert the bars one at a time through the holes in the channel, holding each bar on its mark on the cap rail with one hand while, with the other, you make a fillet weld at the end of the bar between the flanges of the cap rail. Then make fillet welds along the sides of the posts between the flanges of the cap rail. Weld the other ends of the bars to the channel with fillet welds inside the channel flanges, then make fillet welds at the junctions of the channel and the posts. Clean all the welds. Turn the railing right side up, and check its alignment. Align the curves with the posts, if necessary, by bending them cold with a homemade bending tool.
You can use the bending techniques described here to make simple, single bends in mild-steel rods, flat strips, and standard cap moldings — the stock shaped for stair railings. Heavy stock or projects requiring composite bends call for special bending machinery, which is usually available only in metalworking shops.
The first step in making any bend is to mark its location with a soapstone pencil. Then clamp the metal in a vise secured to a fireproof work surface.
Many bending jobs require no other tools besides the torch. To make a bend that is 8 inches or more from the end of the piece of metal, heat the stock at the bend point, then press down on the end of the metal with your gloved hand. If the bend is closer to the end, you will need to slip a length of pipe over the end as an extender. After the metal has cooled use combination square set with a protractor head to check the angle. Then reheat it and make any needed adjustments. Repeated heating and cooling at the same spot will eventually cause cracking and distortion cue to metal fatigue.
When you are bending metal into a curve like the head of a cane — to use at the end of a stair railing, for example — you may have to fabricate a bending tool. There are few common tools that give you just the right leverage at just the right angle to achieve such a shape.
You can make a bending tool from a foot-long piece of stair-railing post stock welded between two pieces of longer channel iron. A piece of bar material, welded to one end, forms a T handle.
You can make smooth curls in thick metal with fixed bending guides, called jigs. These may consist of nothing more than a piece of thick-walled pipe with the same radius as the planned curve. Clamp the jig and the metal in a vise together. Once the metal is hot, simply wrap it around the jig.
Installing the Metal Stair Railing
Attaching a Railing to a Wall
To fasten the horizontal end of a railing to a wall, make a mounting clip by drilling a hole in one leg of an angle iron 1 inch wide, or use an ornamental mounting clip (inset). While a helper steadies the railing upside down on its cap rail, resting on firebricks, clamp the mounting clip to the underside of the railing with a C clamp, then butt-weld the clip to the cap rail along the edges of the angle iron.
To fasten the railing to a masonry wall, use a lag bolt and an expansion anchor, setting the anchor in a hole drilled with a carbide-tipped masonry bit that matches the anchor's diameter.
How to Anchor the Posts
To anchor a railing in concrete (left), drill 2-inch postholes 4 inches deep; center each hole 4 inches from the edge of the steps. Use a hammer drill with a carbide-tipped core bit, available from rental agencies. Set the posts in the holes and plumb the railing, bracing it with 2-by-4s or metal bars; fill the holes with anchoring cement.
For a stairway of concrete veneer (right), fasten a post flange onto the end of each post with fillet welds. Then fasten the post flanges to the stairway with lag bolts and expansion anchors set into holes in the concrete (inset). Drill these holes with a carbide-tipped masonry bit, making the size of the holes match the outside diameter of the expansion anchors.