I have received conflicting views on the benefits of dado versus dowel joints in dorm style, moveable furniture. Some claim that a dado joint is stronger and will prevent racking better than a dowel joint due to the use of glue, even though material is removed to form the dado. Others suggest that a butt joint and dowel construction is stronger. I would appreciate any comment.
(Furniture Making Forum)
From contributor T:
I repair furniture, from new to antiques. I see a far greater failure rate with dowel construction than with mortise and tenon, which I believe to the correct term, vs dado.
If you need more evidence, then build two identical units, one with dadoes and the other with dowels. Now try to make them fail by placing heavier than normal loads and racking them. That's how you will know for sure.
I think contributor T is thinking about actual furniture, not the stuff you find in dorms.
Dowell construction gives very little long grain to long grain mating in the joint. Just look down a cross-grain drilled hole and you'll see there is only long grain on two opposite sides. Since there is little or no strength in butt joint gluing, you end up with a weak glue joint.
That doesn't necessarily mean that dowels make weak joints, though. Whereas you may have a weak glue surface, you still have a joint with a lot of rigidity and shear strength. Plus, you can add as many dowels as wood size reasonably allows.
Bottom line is that your choice will depend upon the end value of your product. A mass produced inexpensive item easily justifies doweled construction. On the other end of the scale, a museum quality piece deserves the extra time and attention required to produce mortise and tenon joints.