Joints and Connections for a Heavy Cabinet
Beginner gets advice on constructing an entertainment center cabinet. May 10, 2005
Question
I am designing an entertainment center. The construction is 1.5 inches wide (2 sheets of 3/4 with iron-on edge banding). I am searching for a way to secure the horizontals to the 8' verticals and I would prefer not to have exposed fasteners. I thought of cam locks, but I would prefer a more professional solution. I built a mockup that used 1/4 steel dowel pins with toe screws. It was pretty solid, but I was told that that is not a common way to fasten boards.
Forum Responses
(Cabinetmaking Forum)
From contributor D:
Dado, glue, clamp.
From contributor F:
This is very different construction. Are you doubling the material because of some unusually heavy items being stored in the unit? If not, this is wasteful. 1"or.75" have stood the test of time in furniture and cabinets. Also, if you are building it really heavy to last and last, I think it is a mistake to use iron-on tape to conceal the edge of your sheet stock. This type of edgebanding is very short lived.
May I suggest .25" solid wood glued and clamped on? An easy way to do it is to rip the sheets to finish width minus edge banding thickness. Then before crosscutting, lay bar clamps across a bench, run beads of glue on the edges to be banded and clamp up four rippings at once by putting the edges with the banding towards each other. This way the depth of the pieces exert pressure on the edges with glue and banding. The edge banding must be wider than the thickness of the material and trimmed flush after clamping.
As far as a construction method, just to be different, you could try half laps with dados. If you don't know what I mean, some people call these egg crate joints. If these were machined tightly and you added dados too, just apply glue and they won't need fasteners. Of course, you will have to go with some other joinery on the outside cabinet members.
From the original questioner:
Thanks. I really appreciate advice from an expert. I make models for a living, and woodworking is something I am trying to learn more about. The 1.5" wide construction is purely for aesthetics. The design is loosely based on a Ligne Roset system that uses faced 1.5" particleboard (or maybe MDF) and cam locks to hold it together (a super nice version of what you might find at Ikea). How do you feel about screwing the horizontals in on an angle backed up by 3/8 dowel pins for strength? Do you think that would be strong enough?
From contributor F:
That does sound like it would be strong enough. Sounds like a lot of work though, dowelling everything. In my shop it would be faster to machine dados because it means only one side of the connection gets labor. For dowels, both sides of the joint need labor. Some people have the machinery to dowel case parts quickly, however. If you did dowel and toe screw, the screws could most likely be seen in some locations. Do you need this to be "knock down" - is that why you resist glue joints? Also, toe screws might be fairly weak in some materials like particleboard. When I said I thought it would be strong enough, I meant it would last proportionately to the iron-on edge tape. None of this may matter to you if you are only designing a system.
By the way, particleboard and MDF can be purchased in 1.5" thicknesses, so no need really to double up .75". Keep in mind that something this heavy and tall, with such a small footprint, can be a hazard if not connected to the building at the top.
From contributor D:
Is it necessary for everything to be 1.5 inches thick for aesthetics, or could you use 3/4 inch material for the sheet stock and use a solid 1x2 face frame to give it the thicker look? It certainly would be much lighter and put a lot less stress on everything.
From contributor R:
I just did one just like this. At the risk of offending the purists, it sure would go faster if you glued two pieces of lightweight MDF together and faced it with something, maybe another piece of MDF if you don't have access to a real edgebander, bored it for your layout, and used flush fitting Rafix with the cover caps. With it all being white, they would be really hard to see.
From the original questioner:
The actual unit will be 3/4" ribbon sapelle ply finished with tongue oil. I just cut the boards down to 11.875 at work today on the panel saw. The next step is to glue the two 3/4 sheets together, then edge band, then tongue oil. The hardest part is going to be buying the TV, which costs a bundle. The Rafix connectors are a good suggestion. I looked at some similar connectors at Rockler called Minifix. I am just afraid that they will show too much compared to some #8 screws. I may make it in 3 sections in case I ever move, so I can glue it together.
Any suggestions on how to go about gluing the 2 12" boards together? I glued one together today using Titebond, clamping with orange bar clamps, followed up by a few 18 GA brad nails. I found that I didn't get enough clamping in the center of the board.
From contributor R:
The Rafix are better than the Minis. The brown or beige flush ones would be hard to see. Hafele sells a very nice jig to install them with if you don't have the boring capability.
As for gluing, Titebond should be fine. Sounds like you need to buy some longer jawed clamps or clamp them between pairs of 2 x's on edge for even pressure. Keeping them straight is the hard part, of course. As for your not getting the centers tight enough, it shouldn't matter as long as the edges are tight; cross your fingers.
I am leery of your edgebanding with an iron. Can you find someone with an edgebander that could put an 8 mm edge on for you? You could also make your own and glue and pin nail it, although I would seriously consider clamping it to be safe.
From contributor F:
A suggestion I would make is to cut your parts oversize in width when you will be laminating them in pairs. This is standard practice for tasks such as this. That way, if there is any slippage or misalignment between parts when you glue up, you have the room to net finish size after you trim them. If 11.875 is your finish size, you will have to make do. (Sounds you went for getting four even pieces from a 48" wide sheet).
Making an educated guess that you do not have an 8 foot cold press, you could try contact cement to laminate your pieces. That way, not having clamps deep enough to reach the center wouldn't be a problem. Just apply pressure everywhere with a block and mallet. This joint would certainly outlast the iron-on veneer tape or commercial edge banding, for that matter. Edge banding should protect an edge, not just cover the core. These tapes are just too thin to do that. One good bump from a blunt object and they are toast. Iron-on will just fall off on its own.
The only way to lam your pieces together with yellow glue and clamps is to use cauls - strong back members (usually crowned in the center) that spread the individual clamp pressure beyond the small circular area that the "F" clamps provide.
From contributor P:
We do this style for one of the designers that we work for. We would put a hardwood cleat 3/4" thick and 1" wide on the 8' uprights. Then plow out a groove of 3/4" on the sides of the built-up shelves. As you install the uprights, put a dab of glue in the groove, slide it on and pin nail it from under the shelf for the lower ones, then on top of the shelf for the upper ones. Make sure you use a 1 1/4" nail. It works great for us - just takes some time.
From contributor D:
Since this is a DIY project, maybe it would work better to get a Kreg pocket jig and use pocket screws to hold the pieces together. They sell hole plugs that would hide the pocket hole and that would be a more permanent joint than the KD fasteners
From contributor M:
Whenever visible shelf pins are forbidden, I just glue biscuits in the uprights, letting them stick out halfway. Then each shelf gets a corresponding slot (that stops short of the face, obviously) so the shelf can slide in from the front after the piece is finished. If laying out for the biscuits scares you, using 1/4” dowels is easier to layout, but won’t allow the shelves to be effectively glued in place when installed.
