While we were repairing the toy a few nights ago (see my previous post<\/a>), my father-in-law suggested that, after the first repair cured, a second application should be considered around the outside. Such reinforcement, he commented, would give the repair its best chance of holding.<\/p>\n I considered his counsel from an engineering point of view: how much extra strength could we anticipate from application of J-B Weld around the outside of the repair site?<\/p>\n Let’s imagine the shear force to be straight forward. The strength of a reinforcement can be, generally, proportional to its left-right length multiplied by its height, then by the square of its forward length. Assuming the J-B Weld works as an integral piece after drying, I imagined an outside application along each side plane. The application would be about 20 times the height of the original shear, then its same forward length, but only about 1\/30 of its left-right length. Compared with the first repair reuniting the two sheared surfaces, the reinforcement strength per side might be 20(1\/30) or 2\/3. Both sides together could offer reinforcement strength of 2(2\/3)=4\/3 or 1.33 times the strength of the original repair, more than doubling its shear resistance. <\/p>\n With these numbers in mind, I took my father-in-law’s advice and made the reinforcement application about 24 hours ago. The repair should be ready right now.<\/p>\n I’ll be sharing more about this fascinating toy repair:)<\/p>\n