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Author Topic: decking boards /sawmills in south america  (Read 2652 times)

Offline JosephCurvin

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decking boards /sawmills in south america
« on: August 05, 2016, 11:12:57 AM »
Hey guys,
i am writing my bachelor thesis topic: increasing the yield of sawmills in southamerica (example with producing decking boards)
I know that  in sawmill there a log is beeing sawed into decking boards with two different widths. does someone know a book or a paper where i can find information about this topic.
i hope someone can help me with this i did not found anything yet :)

Offline Kirk Allen

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Re: decking boards /sawmills in south america
« Reply #1 on: August 05, 2016, 11:33:03 AM »
Decking is cut to the customers desire. I have cut everything from 2" wide to 10" wide. I don't know of any official standard or paper written on this subject though.
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Offline JosephCurvin

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Re: decking boards /sawmills in south america
« Reply #2 on: August 05, 2016, 12:14:00 PM »
hm okay
a question: if you need to produce boards with the sizes 148x25, 98x25 do you try to saw this boards from one tree or do you use 2 logs?

did you use a calculation Software ?

Offline Kirk Allen

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Re: decking boards /sawmills in south america
« Reply #3 on: August 05, 2016, 12:52:35 PM »
If the tree can produce enough lumber for the needed project then it would be cut from that one tree. One tree can be one log or many logs so not sure I am answering your question. 

If I know the total board footage needed for the project you can use Doyle Scale on the log to determine how many board feet are in the log your measuring.
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Offline Stevem

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Re: decking boards /sawmills in south america
« Reply #4 on: August 18, 2016, 12:21:43 AM »
What Kirk is trying to say is a log is not necessarily a tree.  A tree can have more than on log.  
The amount of lumber from a log can be estimated using a "log scale" table.  Factors used to estimate the amount of lumber are diameter on the small end of the log and length.

Also different sawmills can cut different lengths.  All sawmills have a maximum length they can cut.  So a 24' log for one mill might be two 12' logs to another.  Lots of variables. 

The most common scale books (calculators) used are Doyle, Scribner and International.  All give very close to the same volume figure.  In a given geographical are only one book is used. I have no idea what is used south of the USA border.

Here's a link:  http://www.woodweb.com/cgi-bin/calculators/calc.pl?calculator=log_volume  I think there is a metric calculator on the same web site.

Today's large sawmills are all computerized with band saw mills and yields from conifers trees for constructions wood can reach 200% of scale. Part of that is the fact that construction lumber in the USA is cut smaller than actual stated sizes ( a 2" x 6" is actually 1 1/2" x 5 1/2") and sawing accuracy is much better today than when the scale books were written, thus oversize raw boards to be planed to standard sizes are not needed only sanded.    

A band mill has a 20% guaranteed increase of yield over scale because of the thinner kerf of the saw blade on medium to large logs but at a price.  Band mills are more complicated than wheel sawmills.  Kerf (blade thickness) for a band mill runs from 1/16 to 1/8" where a wheel saw blade can exceed 5/16" or even 3/8".

Does that help?

Stevem
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