Glue joints that involve end grain – the ends of the long cellulose fibers that make up the wood – and typically weaker than joints that adhere long grain to long grain. There are two reasons for this, and the first is that wood is strongest along its grain. Keep the grain long, and the joint can be as strong as the wood itself. Glue the ends of the fibers to each other, and the joint can only be as strong as the glue – which is usually somewhat weaker than the wood. The second reason is that en