Want to learn how to bend a wood handrail? While bending a wood handrail is one of the more difficult aspects of stair and balustrade installation, with the right tools, planning and an understanding of the process it shouldn’t dissuade anyone from giving it a try.  The most important things to consider in this process are time and preparation.  If you take the time to make sure everything is set up and organized as it should be then you should have plenty of time when you are actually bending and the glue is starting to dry.
There are several things you will need for this process, as follows:

At least 2 people wearing disposable clothes 🙂
Bending Handrail
Handrail Bending Forms / Mold (2 molds per rail, and same lengths as the handrail)
Bending Brackets or Bending Guides (1 per riser or 1 every 12-18” of floor level)
Electrical Tape or Shrink Wrap
Wood glue – Typically about a gallon per rail to ensure you have enough
A Small Paint Roller and Paint Pan
Clamps: C-clamps or pipe clamps (2 per Bending Bracket or 1 Per Bending Guide + more if needed to clamp the brackets down instead of screwing them.
Shims if using Bending Guides
Broom
Tape Measure
Drill and Screws Paper
Cardboard or plastic to protect the floor if needed
Some people also use latex gloves to keep the wood glue off their hands

Bending Brackets:
The first step in the process is to build the bending brackets.  The basic rule of thumb for the quantity need to bend a rail is one per riser for a stair handrail or one for every 12-18” of floor level bender rail.  There are basically three types of bending brackets that we recommend based on the situation.

If you are able to screw the bending bracket to the subfloor or subtread of a stairway, the simplest bending bracket and the one we prefer is a simple 2x bending bracket.  This type of bending bracket is basically large “L” that is simply made with a 2 x 4 x 12” base and a 2 x 2 x 12” upright.  More clamps are required with this type of bending bracket but we believe it is the best method.

The second type of bending bracket is called a bending guide.  It is a piece of plywood or lumber (we recommend not less than ¾” thick and the thicker the better) that is notched to receive the handrail.  The handrail is then “clamped” using shims.

Finally, in cases where you are unable to screw the bending bracket or guide down to the sub-tread of a stairway, there is a third option.  This is basically a modification of the 2x bracket that allows it to be clamped in place rather than screwed.  This method may be required when the finished treads or false tread caps are already installed.  This method uses the most clamps because they are needed not only to bend the handrail but also to secure the bracket to the treads.

Alright, so now that you have an idea of the bending brackets let’s get down to work.  First, you must determine the position of the handrail.  You will need to know the centerline of the handrail on the floor or treads.  You then use this centerline to determine where the side of the handrail is that will bend around the bending brackets.  If possible it is always easier to bend around the bending brackets than to try and force the center into them.  So, once the edges are known, you align the bending brackets along this line, one over each riser on a stair or about every 12-18” on a floor level.  The bracket should be placed so that the handrail will sit on base of the 2x bracket, or in the saddle of the other two types.   Then you simply attach the brackets by screwing or clamping as necessary.  The brackets should be in the same position on each tread if the stair has open stringers.  For example, flush with the face of each riser and with the surface of the bracket around which the rail will bend, directly over the line where the edge of the handrail will be.  Make sure that you take into consideration the thickness of the bending form you are using.

The next step is to prepare for the bend/curve.  Since this article is about the stair bending process, I am intentionally omitting any description of splicing.   I am assuming that you have a full-length rail.  This is usually about 18” longer than the finished rail needs to be to allow for feathering of the splices and room to cut the rail to its finished length.

The first step is to make sure to lay out all of your clamps or shims depending on the type of bending bracket you are using.  Since time will be critical during the actual laminating process it is very important that everything is ready before you apply the glue.  For example, laying out clamps means that they are in position with one at each bracket and one in between and that they are open and ready to go.  Also, be sure that the stairs are clean of debris so that there are no trip hazards.  Next, assuming that you have the correct length handrail, you start by thoroughly sweeping a section floor about 4-5’ wide and a couple of feet longer than your rail.  You will get glue on the floor, so if this is a finished floor or if that is a problem, you will need to lay something down to protect it.  This can be cardboard, paper or plastic.  Bare floor is the best though if a little glue doesn’t matter.  This is because the paper/plastic won’t try to lift up with the splices when you begin to reassemble the handrail.  Once the area is clear of all dust and debris, layout the splices.  Beginning with either side lay each piece down the same direction next to the previous piece, except for the last piece (or several pieces which I will explain below) which is laid down in the opposite direction.  Each piece should be touching the one next to it so that you can roll glue across several pieces at once without covering the floor.  Carefully examine the handrail splices that are laid out on the floor and make sure that none of the exposed edges are visible.  As I mentioned above, some handrail profiles use two or three pieces to create the outside detail.  You don’t want to apply glue to any exposed finished edges.  If your handrail is a two or three piece outside edge then set these pieces aside to be glued individually.

Now, pour some glue into the paint pan and get your roller ready.  You are then ready to roll.  Take one more look at your setup to make sure everything is ready, you will have about 15 – 20 minutes to get the handrail bent from this point forward.  So, while you will need to work quickly, you don’t have to run so fast that you endanger yourself or make mistakes.  Just a good quick pace will do.  So now, soak up some glue on your roller then begin to roll it onto all of the pieces making sure to apply a thin even coat down the entire length.  Then you reassemble the handrail, one piece at a time, rolling glue on each unglued surface as you go except of course the outer exposed pieces.  Once the rail has been reassembled with glue, add the bender forms to each side and shrink wrap or electrical tape the pieces together in about 4’ intervals.  Just a couple of wraps will do the job.

Finally, you begin to bend the rail around the bending brackets.  You can either begin at one end and slowly work the rail around each bracket (or into the guide) or you can start from the middle and work towards each end simultaneously.  Just make sure that you always work toward an open end and that you clamp or shim the rail as you go.  This allows the rail to move freely until the last clamp on the end is placed.  Make sure that the handrail is sitting flat on the base of the bracket or in the notch.  This will ensure that the bottom of the rail is level.  You will want to clamp at each bracket and at least one clamp in between.  Often the outside pieces are larger at the top and so they tend to want to open up at the bottom.  So, it is important to thoroughly inspect both the top and bottom of the rail for gaps and clam them tight as necessary.  Once the entire rail has been bent, if you are using a bracket type as opposed to the guide, you can remove the clamp from each bracket, except the top and bottom, and re-clamp beside it.  Sometimes the bend may not be a perfect radius and this will allow the rail to flow evenly instead of kink if a bracket is a little out of place or if the radius is not perfect.  While the handrail will not exactly match the line below, it is often less noticeable to have the handrail a little off from the line than to have a kink in it.  It is up to you what you which way you go about this though.

Now that you have inspected the rail for any gaps and to make sure that it is sitting flat the bend is done.  One thing that may help, sometimes the ends don’t want to twist flat.  You can fix this by placing a c clamp securely on the end of the rail then blocking up the handle of the clamp to help twist it.  Often a little over twist will actually help because the rail can relax a little bit when removed from the brackets.  Typically a bent handrail should be left in place for at least 24 hours but 48 is recommended especially in cool or humid areas where it will take longer for the glue to dry.  Once you are finished you simply remove the clamps and brackets, clean up the bending rail with a profile scraper and sandpaper then install it normally with posts and balusters.