6' high=20 | by 5' long & probably 2' deep. She wants to paint the piece, so = question 1)=20 | is cabinet grade plywood what I want to use regardless of finish? |=20 | The shelves on the top of the hutch are to span the entire 5' width = without=20 | breaks. They will be approximately 5' x 20". Assuming I use a lipped = edge=20 | of solid wood to cover the edge of 3/4" ply for shelves in the front,=20 | (question 2) will the shelves need reinforcement at that length & = width?=20 | They will probably be holding china, bowls, dishes, etc. and lots of = them.=20 | I've never used plywood for shelves in that length and am concerned = they=20 | will sag. What are my options? |=20 | Cheers! | Duke=20 |=20 |=20
I forgot myself earlier and sent this in HTML, so, here it is again. As = long as you put a dropped edge on your shelves, MDF seems the material = of choice for your hutch. Given the 5' span envisioned, it seems a = mid-span support is the best bet as this approach will afford the most = capacity. You might have to use this idea as a selling point. It can = be quite an accent to the shelf. Be sure to include a "plate groove" on = the shelf in case your friend wants to stand some of the plates up.=20
Extracted by "Popular Woodworking" from the "Architectural Woodwork = Institute" for their "Winter of 2000" edition.
In general here are the guidelines for how long a shelf can be before it = starts to sag:
Material ------------- Maximum Span 3/4" Thick ------ Maximum Span 1 =
1/6" Thick Solid Wood -------- 36" ------------------------------------- 48"=20 Veneer Core Ply - 36" ------------------------------------- 48" MDF ----------------- 32" ------------------------------------- 42"
The following illustrates how much weight it takes to make a 12" wide = shelf bend 1/4" across a span.
3/4" Thick Material ------------- 36" Span ------ 48" Span Yellow Poplar -------------------- 284 lbs. -------- 117 lbs. Hard Maple & Red Oak ------ 313 -------------- 232 Birch ------------------------------- 348 -------------- 146 MDF ------------------------------- 87 ---------------- 38 Birch Veneer-Core Ply ------- 129 -------------- 54 Birch Veneer MDF ------------ 109 -------------- 46 MDF .05" thick Laminate ---- 205 -------------- 87=20 MDF 1/8" wood edge --------- 79 --------------- 33 MDF 3/4" wood edge --------- 90 --------------- 38 MDF 3/4"x1 1/2" wood=20 edge, dropped ----------------- 241 -------------- 107
Hope all this bumph helps.
--=20 PDQ