Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

The problem with using JB Weld to fill those casting voids is that it won't polish up like the rest of the flywheel. If you are going to paint those surfaces, then it will work fine, but if leaving them in the bright, then not so well. Perhaps a bit of silver solder (the soft kind), would work a bit better, or perhaps actually peen a small bit of actual silver, or coin silver, into the void. Real silver or the solder will darken over time, but so will the exposed iron, and all of it will brighten right back up with a quick pass of crocus cloth or other fine abrasive.

Just thinking out loud here.