For 40 years my parents have used a 4x8' sheet of 1/2" plywood as a table extender for large parties. Dad is finding it too heavy to move safely alone now, and doesn't always have help available to move it when he wants to get it ready for gatherings. It goes on top of a 72" by 28" table and is quite stable; leaning on any edge does not lift the opposite edge.

He asked about cutting it into 2, 4x4' sections with some sort of joint that will maintain its overall stability when installed. He would like to stick with the 1/2" thickness for weight, and would like the pieces to be independent (not hinged) so the weight is manageable. I have a thought, but wanted to throw it out for the collective wisdom to improve.

I am thinking of installing dowels about every 6" along the edge, gluing every other one into the same side (so each half of the board has half of the glued joints) while the other end of each dowel is kept to a firm slip fit. I would place two table leaf fasteners on the joint, like http://www.leevalley.com/US/hardware...=3,43586,43588, a type that not only pulls the edges together but also provides some vertical shear support.

I have the new style Jessem dowel jig for 3/8" dowels. It would be great for drilling and aligning the holes, but I am wondering about the stability of 3/8" dowels in a 1/2" (or so) edge. I could purchase the 1/4" kit for the jig, and may use it again on other projects but so far I found the 3/8" to work well for everything else I have wanted to do so I am guessing it would just gather dust after this. I was hoping that by alternating the glued sides of the dowels it would reduce the tendency of the edge to blow out by giving a solid connection on alternate sides, and by having 8 (or more) across the 4' span there would be enough points to spread the load if someone leans on the end of the piece.

I also have a biscuit jointer (seems too flimsy) and a slot cutting bit for my router, so I could think about a continuous spline or several smaller splines, either backed up with the table leaf fasteners.

Has anybody tried something like this and could share what they learned? Any strong feelings about the best way to do this? They like the one large table approach, as opposed to adults and kids tables set up, so I would really like to make this work for them.

Thanks for any and all ideas!

Matt