Replies

1. 
   RalphBarker | Apr 22, 2012 01:17pm | #1

   tenons vs. Tenons

   Since the plywood panel is dimensionally stable, I see no reason it can't be glued in place inside a dado/groove in the legs and the rails joining the legs (to hide the edge of the panel, and to provide more glue surface). For additional resistance to front-to-back racking, full width tenons could also be cut along the edges of the plywood panel to fit into mortices in the legs. That would simply require a wider panel with which to start. I'm assuming, of course, that the panel is inset from the side face of the legs.

   Under most circumstances, I wouldn't insert dowels into the edge of plywood parallel to the plys, for the same reason it's not a good idea to run fasteners (screws or nails) into the edge of the plywood.  In some cases, however, it might be advantageous to use short dowels at right angles to the face of the ply. But, one still has to consider the effects of expansion/contraction of the solid wood elements, even if minor.

   If you can post a picture of your design, it would be helpful. Otherwise, we're sort of shooting in the dark, as I just did.

1. 
   tony_latino | Apr 22, 2012 06:07pm | #2

   You are right, the panel is offset from the edges - I want it to be inset like an inch. I am just designing it now in sketchup. I am one of those perfectionist types, and I got to the leg, and instantly thought - "wait - I can't do a mortise and tenon joint because the ply has layers". I wanted some more experienced folks info before moving on.

   Thanks for the info, I can get back to sketchup and hopefully have a working plan here soon. I'll post the pic when i have something other than a leg LOL.

1. 
   RalphBarker | Apr 23, 2012 09:20am | #4

   plywood's strengths

   It seems to me that the design trick with plywood is to make use of the entire thickness where possible, rather than reducing the thickness as one would do with solid wood for many joints. The one major exception to that being rabbets for edge joinery.

   Another "trick" is to realize that the ply available at home improvement stores isn't furniture grade - even that with reasonably nice face veneer.

   Then, there's the issue of how the veneer was cut, and the effect that has on finishing - staining, mostly. Getting the stain on the ply to match the stain on solid wood elements often requires additional surface prep prior to staining. The "Finishing" section here is a great source of knowledge and experience in that regard.

2. 
   cblouin | Apr 23, 2012 09:07am | #3

   Slightly off the topic, but are you sure that you want 3"X3" legs on a computer desk? This will be a very heavy looking piece of furniture: is this your intention? I made a 8' long dining room table with 3" legs and they look heavy even there. Sketchup will give you an idea, but structurally, you don't need that much support for a computer desk.

   Regards,

   Christian

1. 
   tony_latino | Apr 26, 2012 04:11am | #7

   My intention is to make a big bold design. I like big looking stuff :)

   The 3 x 3 leg wasn't choosen for structural support - you are right, a thinner leg will do I suppose.

   Of course, it is just in the design phase and all, so it will likely change over the course of the next few months. I visited the furniture store a few days ago and I am already seeing other options and ideas :)

3. 
   tony_latino | Apr 26, 2012 03:59am | #5

   OK, so I finally finished the basic design. I am attaching the pic below from sketchup.

   The inside and bottom panels will be held in place by brackets of some sort I am guessing.

   This design is not complete - it is a rough sketch - there are no textures, color or design elements like edging and trim.

   
1. 
   tony_latino | Apr 26, 2012 04:03am | #6

   And in this picture, I took the top off so you could see the joints and what not

   
2. 
   RalphBarker | Apr 26, 2012 12:10pm | #8

   Weight transfer

   Although it is possible to use the side panels and back of the desk as major structural elements, doing so may add unnecessary overall weight, and result in less-than convenient ways of transfering the weight of drawers (and, contents) to the legs. That is one of the reasons frame-and-panel designs are so popular - with good M&T joints, they work well for that weight-transfer issue. You'll also need some sort of interior structure to which drawer runners would be attached. Again, those are often attached directly to the legs to provide direct weight transfer.

   With the heavy side panels you are showing now, spacer rails could be attached to the interior face of the side panels for the drawers. That would put most of the weight on those panels, particularly the bottom corners. Full-thickness tenons on the side panels into the legs would distribute those forces a little better. But, there's still the question of how to support/transfer the weight on the interior side panels.

   Alos, think about how the desk is going to be moved, and how that will affect your design. Since most people will lift the desk by the top, added overall weight will put that much more strain on the joinery attaching the top.

4. 
   tony_latino | Apr 26, 2012 07:48pm | #9

   5 times - i give up - can't post because the system thinks I am spamming and blocks any attempt to post here. Moving on to a forum that allows people to post questions and comments - thanks folks