Figuring Rough Stock for Moulding Manufacture

      How to estimate the rough material you'll need to produce a given quantity of a particular dimension and style of mouldings. August 8, 2008

What methods are used to convert random lineal feet to board feet when making custom millwork? Of course, you also need to figure in for waste. I can figure out how to go from board foot price to lineal foot price from the calculator but not the random lineal foot to board foot way. For example- someone orders 450' of a 3/4" x 4-1/4" special crown moulding. I need to convert this to board feet to fill the order.

Forum Responses
(Solid Wood Machining Forum)
From contributor A:
Lineal feet times width factor is how I do it. For 450 lineal feet of 4-1/4" crown, I'd figure it on a 5" board. 450 x 0.41667 = 187.50 board feet, roughly. Maybe I'm figuring high or low but this works for me.

From contributor B:
You need to know the face width of a blank. We'd use 4.75" for a 4-1/4" face.

(4.75 x 12 x total lineal feet)/ 144 = Net Board Feet. Add your waste factor anywhere from 1.5 to 2 to get the amount of raw RWL needed.

Net Board Feet (from above) x waste factor = Required Board Feet

From Gene Wengert, technical advisor Sawing and Drying forum:
Because of the poor yield from certain widths, you might also want to consider ordering specific widths of lumber. Let your supplier rip the lumber, in other words.

From contributor D:
I take the finished width,
+ 1/8" for machining
+ 3/16" for saw kerf
+ 15% rip to width waste
Divide by 12 (to get the Board Feet / Lineal Feet)
Multiply by the Lineal Feet x 15% SLR waste x misc waste depending on grade(8% for Select & better)

This would give the board feet of lumber used, but you will need to buy two or three times that amount to sort for correct widths. I would figure 240 board feet for 450' of 4 1/4" moulding using the above formula, and order 500-750 board feet. The extra will go towards the next project, unless it's also 4-1/4".

From the original questioner:
Thanks for the tips on this subject. I really have a grasp now on this figuring out all of the different conversions to go from one to the next.

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