Blanket Chest Design – Lumber Calculations.

Now that the basic dimensions have been established, it’s time to determine how much lumber I need to buy for this build.  At this point, I am calculating for the basic frame-and-panel box and the bottom.  The wood will be poplar, and a good 4/4 rough.  I would actually like it a little thicker, so that I can plane down to a finished thickness of 7/8″.

The overall dimensions of the chest are 48″ long x 22″ high x 18″ deep.  Since the rails and stiles will be 3″ wide, I will need 3″+ wood for that.  I say 3″+ because I’ll be ripping to 3″ in the end, so anything over that will be waste.  Due to this, I’m not thinking so much in board feet(bf) as liner feet(lf).  I’m planning on 2″ tenons on all joints.  For the rails and stiles, the calculations are:

Front & back rails:  4 x 46″
Side rails: 4 x 16″
Corner stiles: 8 x 22″
Inside stiles: 4 x 20″
Total Wood:  504″, or 42 lf.  Allowing for waste, this will require four 8′ boards 3″+ wide.

For the panels, there is a bit more variability.  Panels will be 12 1/2″ wide and 16 1/2″ tall.  The 1/2″ allows for tongues on all four sides.  For the sake of flexibility and to allow for any alignment issues, I’m calling the panel pieces 18″ long.  For the 8 panels, this comes to a total of 12 bd ft.  If I use 3″+ stock, it will take 48 lf, or six 8′ boards.  If, on the other hand, I use 4″+ boards, it will require 36 lf, which will require five 8′ boards.

For the bottom, I’m planning on using tongue-and groove boards running across the width of the carcase.  These will be 18″ long, and 3″ or 4″ wide.  That means that the bottom will require 6 bd ft.  If I use 3″+ stock, that will require 16 pieces, for a total of 24 lf, or three 8′ boards.  If I use 4″+ stock, it will require 12 pieces, for a total of 18 lf, which would still require 3 boards.  The best bet is to stick with 3″+ boards.

So, to sum up, I will need 13 8′ boards 3″+ wide, or seven 8′ boards 3″+ wide and five 8′ boards 4″+ wide.

Now, it’s just a matter of going to the lumberyard.


4 responses to “Blanket Chest Design – Lumber Calculations.

  1. It’s good to see that I’m not the only one who tinkers with the number of baords, based on width. It just feels like knowing the size of your components and how many fit on a specifically sized board is a lot more useful than knowing the raw board feet required for a project.

  2. The trick for me is estimating how much of the wood will be rejected due to knots (and where in the board this knot will fall), and also making sure that the pieces which need to remain whole do so. For example, if you need a 2 12″ wide, 6′ long boards (12 board feet), and they only have 8′ lengths, you need to buy 16 board feet. I spend a lot more time laying out patterns like puzzle pieces on graph paper than I probably should, but haven’t come up with a real methodology for this yet.

  3. Pingback: New Little Good Pieces blog post: Blanket Chest Design – Lumber Calculations : LumberJocks RSS feed

  4. If you interested, and you are somewhat Excel savvy, I have a spreadsheet that really helps guesstimating lumber costs.

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