Microwave\Toaster Oven shelf strength in upper cabinet

[Chris E Smith]

I am designing a 45" wide 16" deep frameless kitchen cabinet that will have a mid size microwave and Breville toaster oven sitting side by side on the bottom of the carcase with a combined weight of 49 Lbs.
The case is 43" tall with two sections of cabinet above the open microwave\toaster oven shelf section. This will be all one carcase with a total of four horizontal pieces including the top and bottom. The top and bottom will be secured with dominos, glue and pocket screws and I'm planning to put a 3/4" applied back on the cabinet for extra strength. The ply will be good quality from a lumber yard not a big box store. The bottom piece where the appliances sit can have an extra wide applied edge band and there will be an additional piece of 3/4" below the cabinet bottom that hides the LED under counter light strip and this can also be as wide as needed to add strength to the shelf above. The applied edges will be maple.

I want to be sure the appliance shelf does not sag over time and I'm wondering what if anything else is needed to make the shelf strong enough. I could make the entire shelf solid maple since I have a lot of this material. I'm pretty sure it is hard maple but it came from an auction of a closed down furniture manufacturer and was not labeled when I purchased it. By weight it seems to be hard maple.

The other options I have thought of are laminating two pieces of 3/4" ply for the shelf, screwing a piece of 3/4" bar channel across the width of the shelf bottom behind the piece of maple that hides the light strip, laminating a thin sheet of aluminum to both sides of the plywood bottom making sort of a stress skin panel.

I don't have a feel for what is needed for long term strength and appreciate any suggestions.

Thanks

Chris

[Peter Kelly]

45" w x 43" h x 16" d kitchen cabinet with an applied 3/4" back? Is this an upper case? Not questioing your motives but that's going to be a headache to install. Upper cases are typically 12" d, much narrower and shorter. Is this an open case w/o doors?

As long as the back has screws running horizontally through into the deck (bottom shelf) it won't likely sag. 45" is really wide though.

[jack duren]

On open weighted shelves we double up on the bottom. If its a 3/4 btm we make it 1.5. Back can be 1/4 as far as its concerned.

[Lee Schierer]

Since this shelf is to be loaded with 50 pounds. I would not trust dominoes. I would set the back and sides of the shelf in a Dado and add a 2" wide face board to the front of the shelf. 3/4" plywood or solid maple should work fine for the shelf.

[Chris E Smith]

45" w x 43" h x 16" d kitchen cabinet with an applied 3/4" back? Is this an upper case? Not questioing your motives but that's going to be a headache to install. Upper cases are typically 12" d, much narrower and shorter. Is this an open case w/o doors?

As long as the back has screws running horizontally through into the deck (bottom shelf) it won't likely sag. 45" is really wide though.

Peter, it is 16" deep and 43" wide to accommodate the appliances. The base cabs are also deeper than normal because there is a 30" deep semi commercial stove oven on that wall that is 30" deep. I have the space for extra depth and thought I might as well make use of it.
Yes there are doors on the two sections above the appliances but the appliance part is just open. I may put pullouts in the middle 18" tall section for easier access. The top 12" section is going to have glass panels in the doors and interior lighting for my wife's bowl collection. Each section will have three doors to match the proportions of cabinets on the other side of the stove.
This is at my home where my shop is located and I have lots of stuff to lift the cabinet into position with.
I could make it two carcases but if\when the appliances are ever replaced it would limit the possible choices compared to one long shelf.