Bolts: Why the Right One Depends on What's Behind the Hole
Grab a generic bolt for a wood deck, a concrete wall, and a steel machine base, and at least one of those three installations is going to fail early. Not because the bolt was weak. Because it was never designed for what's actually on the other side of the hole. Different types of bolt connections call for genuinely different bolt designs, not just different sizes. Knowing which one matches which material is the difference between a fastener that holds for decades and one that spins loose, cracks the material, or never seats properly in the first place. Bolts Built for Wood A standard hex bolt in timber has a problem: nothing stops it from spinning when the nut gets tightened, so someone ends up holding a wrench on both ends just to get it snug. Carriage bolts solve this with a smooth, domed head and a square section directly beneath it. That square shoulder pulls into the wood as the nut tightens, locking the bolt in place without a tool needed on the head side at all. It...