Help - how much lumber do I need to buy?

Preserved:

The 25% loss is what I average – on about 15 serious projects, though, there are many more experienced individuals on LJ. However, ...

Being a CPA, I’m scrupulous in my calculations – see my Project (“Outdoor Bench”, this has a run-through of my process, which I’ve shared – sending Excel files to individuals with the board layouts and cut diagram process). The keys are:
1) Number each board being used, even those which become part of a glue-up;
2) My Hardwoods provider usually stocks 10’ lengths, from 4” to 8”, randomly; that is, I don’t know until I get there.
3) Identify where each board (#1) is coming from (from #2) – be careful to use as much of the width and length as possible;
4) allow 1/4” thickness minimum for planer waste and imperfections in the raw lumber – purchase boards which are straight on-edge – this minimizes the width lost during jointing. Allow about 1/2” to 3/8” on edge – especially if you intend to get two finished boards from a given raw width (ripping uses at least .125 on the Table Saw blade, plus you then have an extra edge to joint).

In this manner, it’s not possible to estimate if 16’ will get you there – it depends on what that 16’ comprises.

I don’t have experience on what the lumber mill will do on planing and jointing the boards – I assume they’ll charge you on unfinished Bdft; then a planing/jointing charge, with no guarantee as to post finishing boardfeet.
MJCD

-- Lead By Example; Make a Difference

Because you are ripping down to narrow strips, you will have a lot of saw kerf loss (in the form of sawdust), so this will definitely affect your yield. Figure out the saw kerf loss, which is usually 1/8” on most tablesaw blades, and then you have to joint off about 1/16” on each side, so that is at least 1/4” loss on each strip. You will need more than you think. If you were making a wide glued-up tabletop out of normal width boards, the 25% extra would probably be fine, but not if you are milling out a bunch of narrow strips.

I am never satisfied with pre-planed lumber. It tends not to stay straight as the wood changes with the environmental conditions. I like to plane and joint my own stock to get it perfectly flat and straight before gluing.

-- Wood-Mizer LT15

You haven’t said how thick the countertop is going to be . If it is 1” thick then the 12 BF is right but if 2” thick you will need 24 bf. Board feet is length x width x thickness.

-- Bruce

The new counter top will be the same as the old. 1.25 inches thick.

I measured the old top:

25×27x1.25
20×27x1.25
31×5x1.25
Total 1712.5 cu inches
1712.5 / 144 is 12 board feet of lumber?

Am I understand this correctly? Then I’ll need to buy extra for sawdust loss.

One other thing that can throw your numbers off is getting the most of your lumber lengthwise. If you know ahead of time what the length of the stock is that your supplier gives you, you can form a rough idea of your cuts before you head to the store. For instance, when I was making a new top for a cedar chest, the length was something like 40 inches. My supplier stocked 12-14’ ERC boards, so I knew ahead of time that the 12 foot boards would give me 3 40” boards, with about 2’ left over to allow me to account for cutting the ends off, saw kerfs on cross cuts, and a little wiggle room for picking the area of grain i liked. The 14’ boards would give me 4 lengths, but with only about 8” to spare, which in my mind, was cutting it a bit close.

-- - The mightiest oak in the forest is just a little nut that held its ground.