I am building kitchen cabinets using 3/4" oak plywood. I'm using dado cuts into the side panels for the shelves. In a magazine i get, it talks about using a biscuit joiner on cabinets. I've used biscuits to attach faceframes to the box, but I've never tried using them to attaches shelves to the side panels. Is this a feasable option? Can biscuits hold the weight of heavy dishes on shelves? Most of the top cabinets would probably get three biscuits on each end of the shelf. If seems that there's not alot of wood to support the weight of the shelf and the dishes.
I don't think biscuits were ever intended for support. They can certain reinforce something like a corner butt joint on a frame, but never anything like shelves.
Hardwood splines, glued in place would have the strength you're looking for. However, with plywood, keep in mind that if you put splines in the center, only half the plies will be holding the weight. Dadoes would be the simplest and strongest option, imo.
Contrary to conventional wisdom, and providing you use a sufficient number, say every four evenly spaced biscuits on a 12" deep wall cabinet with butt jointed shelves, properly glued biscuits will prove plenty strong enough to support most kitchen cabinet shelf weights.
The question is why?
You will find that adjustable shelves make much more sense. Dadoing your top and bottom "*floors", and making all intervening shelves adjustable will give you much more flexibility in cabinet utilization and convenience.
(*in kitchen cabinet parlance, the top and bottom of the cabinet, since they are usually the same dimension, are generally grouped in your Cutlist as a "floor')
I just built a set of cabinets using 3/4" Oak. I prefer having adjustable shelves so I used these:
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used pocket holes (and glue) to fasten the face frame to the carcase. I used dadoes for the bottom shelf (base cabinets) and dadoes for the bottom of the wall cabinets. What span for the shelves? I found that 1/2" plywood was adequate for shelves. I added a strip of 3/4 oak across the front of the shelves but it was mainly to cover the edge of the plywood. It, of course, strengthened the shelf as well.
I would never build a cabinet with permanent shelves. Put in rows of holes to install shelf supports. Seems like when shelves are permanent the stuff you are going to put in is just a little too tall or you need to stack smaller items. Don't ask how I know this. (grin) WW
I'd say, don't do it. The dado, especially if un-housed, shows only a horizontal crevice, and crumbs wedged in won't spring the sides or loosen the shelf. Use the biscuits to make deep shelves of solid wood (better strength against sagging), instead.
Dado cuts are at least as easy as accurate biscuit placement in a side panel.
My current kitchen, that I built 20 years ago, I used biscuits to butt joint shelves inside the cabinets. Still holding up fine. But if you are going to dado the sides for the shelves to fit into there would be absolutely no reason to also use biscuits.
Fixing the shelves in position may prove a regrettable decision sometime down the road.
Instead, drill the inside cabinet walls to accept shelf pegs every X- inches (look in one of your publications for recommended spacing) and rest assured that, for all but the widest of cabinets, even MDF shelves will hold the weight of the dishes and such they are called to support.
A better use of effort and $$$ might be a design incorporating "pull out" shelves (especially in "tall" pantry cabinets and base cabinets.
One other suggestion - Pan Drawer base cabinets. My wife loves them. Large, wide drawers she finds ideal for pots and pans.
One other thought - since only one side of each "end" wall cabinet is "exposed," why not save a few bucks on the "interior wall cabinets and ditch the oak in between?
Instead, drill the inside cabinet walls to accept shelf pegs every X- inches (look in one of your publications for recommended spacing) and rest assured that, for all but the widest of cabinets, even MDF shelves will hold the weight of the dishes and such they are called to support.
----------------------------- Check out this Rockler page.
I agree, Lew. And if I am going to make an adjustable shelf for inside a cabinet, I don't drill 100 holes from top to bottom. I estimate where I think the shelves will be, and then put about 6" worth of holes in the sides. The sight of those empty holes has always bugged me for some reason. When I have installed IKEA purchased cabinets, I was able to buy hole covers (like you buy as screw caps, but with a 1/4" body) and that was a great thing. Can't find them now....
But back on topic, a simple jig is easy to make and use in these applications. It doesn't take long and even if it is for a one time application, I would save the dough.
When I am retrofitting a kitchen or building a "one off" cabinet as a bookcase, pantry, electronics cabinet, or anything else that might need to hold a lot of weight but needs to be adjustable to the whims of the owner, I still like these:
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come in a few different colors from different manufacturers, and even the small shelf clips from these systems (3/4" X 1/2") can match or compliment your cabinet finish. My clients have happily loaded everything from law books and bowling trophies to warehouse club sized canned goods on them for years. Never a failure.
I am surprised, though. While clicking through a couple of pages on those standards, I am surprised they no longer offer "oiled bronze". Every office finish out I did for years seemed like the clients wanted a light walnut stain on birch plywood ( nasty.... ) and those bronze colored standards in them with matching clips.
I like the fact they were enormously fast and easy to install, too. When out on the job, I cut the slot/inlet groove with a router and a straight edge. In the shop, two passes a side with a dado on the table saw and finished.. Like I said, they are really fast, and if you cut your inlet groove so that the metal sits on top of the bookcase/cabinet floor, they line up perfectly. with no measuring at all.
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