I’ve been getting a lot of calls lately regarding “How do I bend a wooden handrail?” Bending handrails, even for some of the most experienced woodworkers, causes fear and dread. Well fear not!
Here are some basic tips to get you started:
If the net length of the rail you are bending is 12 feet, it is best to use a 14 foot bent rail to ensure the ends are pulled around the desired radius to hold their shape when you remove the rail from its clamps. If you have 13 “rungs or steps,” you’re safe with a 14-foot bender for an inside radius. If an outside radius goes up a stair, calculate 2 feet per step. Rail bending is understood when you imagine a standard handrail profile cut into thin strips and joined (tongue and groove joints to create alignment). The bending mold should also be included, as it is molded into the outer profile of the handrail and is used to sandwich the handrail and allow attachment without damaging the handrail itself.
Weldwood’s plastic resin glue (a product of DAP) is perhaps the ideal glue for bending handrails. It has a 24-hour cure time, allowing plenty of time to bend the rails without feeling rushed. It also sands easily once dry and works on stains. The best place to find this product is a True Value Ace hardware store. I understand that they bought the rights to sell this product, which took it off the shelves at every Home Depot and Lowes. It comes in a one pound plastic container and is mixed with water until thick. Apply it to both sides of the bending rail braces, tape or wrap the rails together, and you can start bending!
When considering steam bending, it is best to apply Weldwood after the handrail has been steamed and bent over the forms. Remove it from the forms once it is dry, apply Weldwood and put it back on the forms. Steaming handrail, for most styles, is not an option unless your flex rail is less than an 18-inch radius. For some handrail styles, the minimum before steam may be a 24-inch radius.
One key to preventing stress points in the rail shoulder from cracking or breaking is to apply vinegar to the stress areas of the wood. The vinegar reacts with the fibers of the wood to relieve stress. Don’t use bleach! Will permanently stain some hardwoods black.
Once a handrail is bent, use an orbital or belt sander to finish the job. Make sure all the glue is sanded down properly, otherwise one will have stains where the stain cannot penetrate as the glue acts as a sealant.
C-clamps or bar clamps are the two best handrail bending tool options.
Also, as a helpful hint, there’s a book called “The Stair Builder’s Guide” by Coffman Stairs that has a whole chapter on how to bend handrails (with pictures!). The book is no longer in print, but copies are available. Available through Amazon.com.
