How much wood needed after the sawblade takes it's part.

[Mike Sellers]

When you look at a boardfoot number, is there a quick way to calculate the waste factor % for a given board size, say .50x.75x36"? Or must you just deduct the blade width times the number of times you have to cut before the board is used up?

 

[mfisher]

The board length calculated accounts for the blade kerf. What it does not add is a safety margin or extra material for additional segments.

In WTP the summary sheet on the right gives two board length. Economy and Grain Match. Economy is cutting the segment flipping the board.
Grain match is when you do not flip the board.
Segment Pro gives the economy length.

If I am making a 12 segment ring I generally will cut 2 or 3 extra segments as spares. I also add about 3 inches for a safety measure. Need enough material to hold the board against the fence and not have it more when cutting.

 

[Ken Sherwin]

I add 3" to the board length for each row for a handle when cutting the last segment or two. (I like to keep my fingers that far from the blade.) Then the longer board length times the board width gives me the area for that row. Finally I make allowance for board thickness or row height if I'm using 2" material on a big vessel. Totaling up the volumes for all the rows gives me the minimum wood needed then I add about 20% for unusable scraps and sawdust. I'm fortunate to have 2 saws so I set one up to crosscut the current row's segments and the other one to rip the next row. I start with the row that has the largest board width and work my way down, ripping down a stick if I have some left at the completion of a row. This way I actually have very little real scrap but still figure 20%.

Does this help?

 

[Mike Sellers]

Thanks a bunch for the help and putting up with a newbe.

 

[Ken Sherwin]

Every one of us was a newbie and got help from someone else at one time and still do.

 

[Holger]

Also use a thin kerf saw blade, they are .10 thick. It starts to add up when you are making 48, 72 or more cuts.
48 cuts is 4.8 inches of waste plus 3 or 4 inches to hold for safety. So 48 segments will require almost 10 extra inches.