As a finish carpenter, I would put stairways and curved
millwork near the top of my list of most demanding tasks.
Combine the two and you’ve got a real challenge: curved
handrails. A millwork shop can glue up the curved rail stock,
then shape the profile. But for those of us doing the job on
site, the most practical method is to laminate the piece from
The staircase shown here included a curved balcony and several
sections of curved handrail. I used rail parts from Johnson
a local manufacturer and distributor of stair parts and
millwork. Most of the company’s handrails are 2 1/4
inches wide, but for this project we went with a beefier
profile — #6210, which is 2 5/8 inches across. The
bending rail consists of nine interlocking strips of wood that,
when glued together, have the same profile as the solid rail.
Because you can’t clamp directly against the sides, the
material comes with a pair of bending molds —
negative-profile pieces that protect the molded edges while
providing a flat clamping surface (see Figure
Figure 1. Bending rail is made up of interlocking
pieces of wood that join to form the profile of a solid
handrail. The outer pieces are bending molds — which are
used during glue-up to protect the rail and provide flat
Getting Set Up
The simplest way to form a spiral rail is to clamp it along the
edge of the staircase itself. When I arrived on site, the rough
stairs were in place and drywall had been installed on the
I began by locating the centerline of the rail, which depends
on the baluster location. I normally line up balusters with the
outside face of the skirtboard, or, as in this case, the
3/4-inch-thick decorative brackets. We planned to use 1
3/4-inch balusters, which put the centerline 1/8 inch in from
the face of the drywall.
Bending guide. In order to have something to clamp to,
I screwed L-shaped bending guides to each tread. I made the
guides from 1 1/8-inch plywood with 3/4-inch OSB gussets; they
needed to be rugged because they hung over the edge of the
staircase and would be subject to considerable stress
(Figure 2). We used similar guides to bend the
balcony rail, but since we were bending it on the flat there
was no need to bend it around the balcony framing. Instead, we
scribed the arc on the floor of a nearby room, screwed the
guides to the line, and laminated the rail there.
Figure 2. In preparation for making the spiral
handrail, the author screws bending guides to the rough stair
(left). For forming the balcony rail, he uses guides screwed to
the floor of a nearby room (right).
Accounting for springback. To accommodate the
springback that occurs when curved laminations are removed from
the form, I positioned the guides to overbend the curve
slightly. I did this by installing the first guide on layout
halfway up the stairs. On each successive step — up and
down — I pushed the guide 1/16 inch further out from the
edge of the stair, for a total overbend of about 3/8 inch at
each end. The rail sprang back a little more than expected, but
not enough to cause a problem (see “Calculating
Springback,” page 5).
When you don’t use continuous backing, as in this case, a
bent lamination will tend to flatten out between the last two
clamping points. To prevent fitting problems, I ran the rail
long and provided an extra bending guide at the top and bottom.
This allowed enough extra length that I could cut off the flat
spots and still have a long enough piece.
Twisting the rail. When bending rail is used to create
a spiral, the railing needs to be twisted inward slightly as it
spirals up the stairs. This requires a lot of downward
pressure, so we provided clamping points by screwing short
lengths of 2-inch plastic electrical conduit to the rough
treads. The end of an F-clamp fits nicely into the pipe, and
you can clamp pretty hard against it provided it’s
fastened with long washer-head screws (Figure
3). Plastic plumbing pipe won’t work because
it’s too brittle.
Figure 3. Short pieces of 2-inch plastic electrical
conduit fastened to the floor (left) provide rugged clamping
points for twisting the rail into a spiral (right).
Glue-laminating is all about preparation. I always do a dry run
first to make sure the guides will hold up and that everything
I’ll need is in reach (Figure 4). Once
you start gluing, there’s no time to run out to the truck
for something you forgot.
Figure 4. Before applying glue, the crew does a dry
run to determine which clamps to use, where they should be
placed, and whether additional clamping points will be
The better you plan, the more time you’ll have for
clamping before the glue begins to set. For simple laminations,
I use regular Titebond, spreading it quickly with a 3-inch
paint roller. Since this was a complicated glue-up, I tried
Titebond Extend — which has a longer open time —
but it helped less than I expected: Some of what we gained by
using slow-setting glue was lost because the glue was thick and
had to be spread with a stiff bristle brush (Figure
Figure 5. With the bending-rail strips stacked in
order, ready to go, the author and his helper spread glue (top
left) and laminate the rail piece by piece (top right). With
the assembly sandwiched between bending molds, they secure the
bundle with plastic stretch wrap (bottom) to keep it from
coming apart as it’s being clamped to the guides on the
Before gluing, we sealed the MDF molds with lacquer and a coat
of wax to keep them from sticking to the work. Then, working on
a nearby bench, we placed a side ply in one of the molds,
spread glue on it, stacked the next piece on top, spread more
glue, and so on until all the pieces were glued and stacked
between the molds. I secured the bundles every few feet with
plastic stretch wrap to keep them together while we moved them
into place and clamped them to the guides.
Clamping. With bending rail, I have a simple formula
for how many clamps to use: every one you’ve got (see
We used one clamp per guide and two smaller clamps between
guides, starting in the middle and working toward the ends one
guide at a time (Figure 6). You don’t
want to clamp too far ahead, or you could capture a wrinkle and
create a gap between laminations.
Figure 6. The rail gets clamped to the guides while
the glue is wet, starting at the center and working toward the
ends (top). The process takes a lot of clamps, for both
squeezing the plies together and bending the assembly to the
curve (bottom left). The balcony rail is bent in a similar
manner, with wood wedges providing downward pressure (bottom
There’s always a lot of squeeze-out, so we protected the
finish surfaces below and used damp rags for cleanup. Rather
than wipe the excess glue off the rail, we waited until it
firmed up to scrape and sand it off. This doesn’t make
extra work — we always have to sand because the plies
don’t line up perfectly.
Figure 7. When the glue has cured, the author removes
the clamps, scrapes and sands the rails, and then installs them
with the same kinds of fittings used for straight rails.
Finishing up. We left the clamps in place until the
glue had fully cured, then scraped and sanded the railing to
create a smooth profile. From that point, installation was much
the same as with straight rails (Figure
Chas Bridge is a finish carpenter in Sequim, Wash. Special
thanks to Candy Pitman for photographing this project.