Could somebody please check my math

[Brian Brown]

This should be so simple, but the more I look at it, the less confidence I have in my calculations. I am making a built in bookcase, with three adjustable shelves. The dimensions are 51" tall, 30" wide, and 14" deep. The walls, top and bottom are being made from solid wood and the back from veneer over MDF. I have attached a drawing of the carcass, with the dimensions. My calculations show about 15.75 bf for the carcass, and just under 3 bf per shelf. A total of 25 bf plus about 20% for waste, giving me a total of 30 bf. It seemed when I conceived this project that it should be less (I am comparing to an earlier larger project), and I have no idea why my brain won't work today. Are my caluclations right? I am not counting the back because it is not made of solid wood.

Thanks for the help.

Brian

[Randy Klein]

51" tall, 30' wide, and 14" deep

30 feet wide?

[Brian Brown]

Sorry, typing too fast. Now you see how my brain is working today. It is 30 Inches wide.

Thanks

Brian

[Michael Weber]

15.75 is what I get.

[Chris Friesen]

Assuming you're using nominal 1" wood everywhere, your calculations are correct.

Also, 14" is pretty deep for a bookcase. If you were to make it 11" deep, you would save 21% in materials.

[David DeCristoforo]

51+51+30x5=252 lin. in. X 14" = 3528 *X 144 = 24.5 (BF) + 30% = 31.85 BF

Your milage may vary based on the actual lumber sizes you get. If all your stock is 8' for example, you will probably have more fall down than 20% (which is why I used 30%)

[Greg Peterson]

"51+51+30x5=252 lin. in. X 14" = 3528 *X 144 = 24.5 (BF) + 30% = 31.85 BF"

Assuming one inch stock, I get 51"+51"+30"+30"= 162" X 14" = 2268 Sq Inches / 144 = 15.75' BF.

[Tom Veatch]

[quote=Greg Peterson;619437
Assuming one inch stock, I get 51"+51"+30"+30"= 162" X 14" = 2268 Sq Inches / 144 = 15.75' BF.[/quote]

It wasn't stated specifically in the OP, but the implications are that there will be 3 shelves. Add those and you'll be at 24.5 sq ft (board feet per nominal inch of stock thickness)

[David DeCristoforo]

Ya left out the shelves.....:)