High Strength Color Zinc Countersunk Short Square Carriage Bolt Flat Head

Cause: Particle board furniture nuts, especially T-nuts, are made from softer metals. It's very easy to over-tighten them with a power drill or a wrench. The number one rule is: hand-tighten until snug, then only a quarter to a half turn more with a tool.

Solution: If you strip a T-nut, you usually have to replace it. For a standard hex nut, you can try a replacement from a hardware store.