Table of Contents
Making the laminated arch beamA supporting member.
Step 1. Making the template for the arch
To make the arch template, 3 stakes will need to be hammered firmly into the ground and braced opposing the bending force.(see picture).
Space the stakes as per the dimensionsAny of the three linear measurements, length, breadth and depth. shown in the accompanying picture.
The arch beams the are made by bending and gluing and screwing four lengths of 90mm x 19mm (3/4″ x 3 1/2″) treatedPressure treated. Refers to lumber that is treated in such a way that the sealer is forced into the pores of the wood. Refers to lumber pressure sprayed with chemicals to lengthen its life expectancy for outside use or inground applications. pine together.
When the glue is dry (the next day) this newly made laminated arch beam can be ripped (cut) down the middle (lengthwise) to create two arch beams for the base of the bridgeA structure that allows people or vehicles to cross an obstacle such as a river or pond or garden., one each side. (See Step 4 “cutting the arch boards”)
The arch handrail is made the same way, using the same template.
Step 2. Making the laminated arch beam
Bend a piece of 90mm x 19mm (3/4″ x 3 1/2″) knotThe portion of a branch of a tree that appears on the edge or face of a piece of lumber. Usually a circular mark on a board or piece of lumber showing where the branch was. free boardA piece of sawn, or dressed lumber of greater width than thickness. Usually 19mm (3/4") to 38mm (1 1/2") thick and 75mm (3") or more wide., 2400mm (8ft) long, between the arch template pegs. Bend a second board against the first, putting a generous amount of glue between the two boards.
Repeat this action until four boards are in place forming the arch.
Clamp the boards together and also screw along the arch approx every 300mm (12″) with 50mm (2″) stainless steel screws on both sides.
Ensure no screws are placed along the center line of the arch beam as this line is to be cut.
Many thanks for the article on the laminated bridge. My daughter had asked me to build her a bridge to go over her pond, and after looking at many plans I decided that I could cope with your plan. I had been given a lot of mahogany by a friend who lives near by from a conservatory they had pulled down…
Harry from England
I need a arched bridge that would span a creek that is 12 feet wide with sloped banks
How do you cut the arch in two with a circular saw? (4) 1×4 beams laminated together will be 3 inches thick, but most circular saws can only cut to a depth of 2.5 inches. Also, that’s a long cut – how do you keep it straight?