Bending Rail from a stair parts manufacturer is designed to han- dle both the bend and the twist of these forces. The local lumber yard ordered the oak bending rails. The bigger challenge for this project was the construction of the stringers, especially the caps, which had to be laminated a few layers at a time and shaped to match the treads along the way.
RIGHT GLUE After much debate, Robert chose DAP Weldwood Plastic Resin Glue for two reasons, open time and stability. Open time refers to the amount of time you have to get things into place once you mix and spread the glue. If the glue sets too fast, it will hinder the bending process and could ruin your expen- sive bending rail. Glue stability is the next consid- eration. We saw that standard yel- low carpenters glue had a certain amount of elasticity that may allow the layers of rail to creep under pressure for a long period of time. Robert was looking for a glue that would be as stable as possible over the long term.
CODE CONSIDERATIONS Stairs must be built to specific building codes, and several code requirements come into the picture for a project like this one. Tread and riser sizes, guardrail/handrail heights and baluster spacing are among the top priorities. Be sure to check that the tops of the knee- walls are parallel with the stair nosings. Guardrail/handrail heights are determined by stair nosings, not the knee-wall. Adjust the knee-wall with temporary shims, if needed, before bending the rail. Check your local codes and plan accordingly.
HOW-TO TWIST A
BENDING RAIL The following is how we laminated, fit, drilled and assembled the curved handrails.
We attached clamping boards vertically up the sides of the stringers. These boards were about three inches higher than the top of the stringers, and the ends were cut at the rake angle of the stairs.
We rough-cut the end of the bending rail to reach past the newel post location but not reach the floor. After mixing the plastic resin glue according to instructions, we spread the rail pieces out on the floor and applied the glue using mini rollers with foam roller covers. We re-stacked the glued pieces and wrapped the assembled rail with stretch-wrap film in a few places. We also taped some wood pieces to the lower part of the rail that matches the bead and builds the bottom out flush with the top. The rail was placed on top of the stringer and against the clamping boards. The rail was clamped about every 6 inches from top to bottom.