I use the counterweight shown here to balance movable insulated shutters, such as the ones shown in FHB #28 on p. 46. The beauty of this weight is that I can adjust it while it’s in position, rather than running in and out to the truck to file away at a piece of iron bar stock.
The basic container is a piece of 2-1/2-in. dia. clear acrylic tubing. I’ve found that tubes between 1 ft. and 2 ft. long will do for most shutters. I glue acrylic caps to each end of the tube; the upper cap incorporates an eyebolt with a pair of nuts and washers.
To load the counterweight, attach it to the shutter’s draw rope and make sure the shutter is in its open position. Insert a funnel into the fill hole in the cap, and slowly add dry sand. When the shutter starts to move, stop adding sand, and pull on the rope to bring the shutter to its closed position. It should stay put. If not, adjust the counterweight accordingly, and cap the filler hole with a dab of silicone caulk. The finished weights can be dressed up with a tube-sock covering, or you can use colored sand or marbles for ballast.
Bryan Curry, Attica, NY