boardfeet question


I'm interested in possibly buying some Black Walnut logs that are described as straight, 20" diameter, 6-8 ft in length, and having them milled. Is there a reliable way to estimate the boardfeet that might be gotten from such a log? I'm trying to decide if the cost would be worth the effort to get the wood.
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Cubic inches divided by 144 minus say 20% for drop.
Just a wild ass estimate on the drop. Maybe some day I'll have a mill and really know what I'm talking about.
Or; from the wonders of Google and the web...@ http://www.uwex.edu/ces/ag/sus/wood/pdfindex/wman03.pdf
Process Overview The purpose of saw milling is to produce lumber, cants, timbers, and other high value wood componentsfrom the log. In the processing of a 14-inch diameter log into these products at the typical Wisconsin sawmill, approximately 28 percent of the log is bark, 14 percent is converted to coarse residues (chips), 14 percent is converted to fine residues (sawdust), and 43 percent is solid wood--lumber, cants, and the like. Smaller logs produce more course residues and less lumber (10-inch log is 40 percent lumber; 6-inch log is 25 percent lumber); larger logs produce slightly more lumber and less course residues.
The residue sources from a debarked log in a typical Wisconsin sawmill are 7 to 18 percent sawdust, 11 percent edging strips, 3 percent edging errors, 11 percent end trim, 5 percent slabs, and 3 percent excessive lumber thickness.
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http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr01.pdf Called "cheatin' sticks" in the industry. Take your pick.
http://www.fpl.fs.fed.us Will also find some dandy information on stacking and drying as well.
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You will get between 96-128 BF of lumber......Brian
www.members.cox.net/bsnikitas

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You will get 96-128 BF of lumber........Brian -- www.members.cox.net/bsnikitas

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No idea for black walnut. On English walnut you mill everything, then look at the boards before you haggle. The stuff is so valuable and so variable that you really have to see the quality of the figure before you decide. I can't imagine how they work it out for _real_ walnut (Armenian) -- it probably involves marrying off daughters.
For general logs you can use an ancient measure like "Hoppus feet" (a Victorian pocket book of "diameter at chest height" to expected yield calculations). There are modern equivalents, usually mandated by your local government or industry body - for you guys there's one in the US Forest Products handbook (George will undoubtedly post the link to the PDF in a minute 8-) ).
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You should also find out if anyone will mill them. Not all mills will take just any log. If they come from areas with people present, urban/suburban, there's a good chance they'll have nails or something in them. Sam
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A portable bandsaw mill will usually mill anything. They're safe if they hit something metal and the blade damage cost isn't so prohibitive that it makes it impossible. Usually the deal is that the log owner pays for any blade wear or damage, and most of the time you get away unscathed.
It's not usually (I'm talking about the UK) worth the labour costs to set a portable mill up for just one log, _except_ in the case of walnut. Or else if you just want the logs disposed of anyway, and slabbing them is saving you crane truck hire as well.
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Doug wrote:

Woodweb has a log volume calculator. See:
http://www.woodweb.com/cgi-bin/calculators/calc.pl?calculator=log_volume
--
Jack Novak
Buffalo, NY - USA
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Doug wrote:

You said they are "straight" so it is just
Pi * d X l (diameter and length)
Use all inches --- so a 6' log
3.14159 * 20 * 72 = 4524 cubic inches
for BF -- 4524 / 144 = 31
Normally professional foresters estimate a "conic section" and they have standard waste factors for the boards -- and then the sawdust and scrap goes to the grinder to be used elsewhere -- mdf etc.
The logs have already been "bucked" to a consistent form factor by the sound of it so just use the simple cylinder method as above.
Try 20 to 30 % waste as a guess -- you won't know till you mill a few logs from the same stand or tree -- and for that few --- not worth anything but a guesstimate. You get what you get.
We can get badly milled cherry here in Ontario for less than $2 a board foot -- about 40% waste by the time you mill it up for a table. That's behind some of the guesses.
Based on 20 board feet -- milled -- working out to one end/occasional table for a living room after final cutting and delivering one table using about 11 to to 14 board feet -- well there you go -- one table per 6 foot log. Again -- assuming a further 20 to 40% waste -- _after_ the log has been converted to "lumber" like 4/4 or whatever.
So if it is $1.50 to $4 a board foot cut into lumber -- yeah -- I would do it. Otherwise I would strike a deal based on final usable "rough milled" lumber.
Skill of the sawyer is everything -- last rough load I processed was roughly trapezoidal 5/4 lumber and I needed 4/4 rough to mill to 3/4 s4s -- waste of cherry.
In other words -- pay for a _good_ sawyer and have some idea of what you will make -- or you will have a lot of waste -- or alternatively have to glue things back together.
Hope that is clear.
-- Will R. Jewel Boxes and Wood Art http://woodwork.pmccl.com The power of accurate observation is commonly called cynicism by those who have not got it. George Bernard Shaw
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WillR says...

Not quite. It is Pi x r^2 x l with r = radius, then divide by 144. That works out to about 183 BF for a 7' log before subtracting waste. Even at 40% waste, he should get well over 100 BF. Makes me wonder why we pay so much for wood.
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Hax Planx wrote:

Oops -- wasn't thinking -- too much of a hurry. Thanks.
<Pulls applied and theoretical Math degrees off wall and hides them quickly>
lol
The only excuse I can offer is that my mind (little that there is left) was on the usual "clipped cone" that is used in forestry calculations -- more in softwood I think but still -- embarrassing .
Circumference -- sheesh...
-- Will R. Jewel Boxes and Wood Art http://woodwork.pmccl.com The power of accurate observation is commonly called cynicism by those who have not got it. George Bernard Shaw
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WillR says...

Not a problem unless one of your former professors see the post. There's nothing quite like that look of horror.
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Just admit it, Will. You were thinking rotary-sawn veneer. *grin*
"Where there's a Will, theres a way. Depending on the size of the tree,"
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Robert Bonomi wrote:

I'm not even gonna try explaining my way out of a faux-pas like that well OK -- SWMBO hassled me three time last night while I was writing -- got _nothing_ correct. She wanted to take me out to dinner -- the miserable wretch -- and all she did was hassle me...
When I screw up there are no half measures. LOL
--
Will
Occasional Techno-geek
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Posted a compendium of ways of estimating yield, which, by their sheer number, should be a clue that this is not a science.
Note that the price of wood is based on the number of usable planks, and you won't have to wonder about price.
Sawing through-and-through is not going to produce the greatest number of high-grade boards.
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This is the doyle scale. www.callkits.com/doyle.htm
-- www.members.cox.net/bsnikitas

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