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Doyle, International, Schribner???

Started by rathbone, March 11, 2006, 06:14:14 PM

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rathbone

Hi all,
new in the business and need some info on lumber scales, i'm sure it sounds silly to you who have been in the biz, but for me, its a mystery.  What are the differences, which is used and for what purpose?

I'm getting close to a decision on the mill type (Perteson ASM), and would like to running by this fall.  I am in the process of trying to figure out how best to get logs.  I will doing this part time until I see which way the business will go, for now, I just need raw material to get me started and to hone my skill on the mill.

This forum is THE place to get anwsers on these questions, I know you won't let me down and I hope you guys & gals don't mind too many stupid questions, but I know I will have a lot of them...

Rathbone. :)

Jeff

I just happen to have that information easily at hand since its part of my timberbuyer.net website. :)

You can see realtime comparisons of the scale using our Forestry Forum calculators in our "Toolbox" by clicking the little red toolbox near the bottom of the column to the left or THIS LINK
;D
What are Log Rules?

    Since the first sawmill was built in the United States, over 100 log rules have been developed, using a variety of methods. Some were based upon the lumber tallies of individual mills, others were developed by diagramming the cross-section of boards in the ends of logs, while still others were developed using mathematical formulas. In general, log rules must account for the taper that exists in all logs, saw kerf (or the loss of wood as sawdust), and a fixed procedure for removing wood on the outside of the logs for slabs. The Doyle, Scribner, and International log rules are probably the most widely used rules in the eastern United States.


Doyle Log Rule

The Doyle Log Rule, developed around 1825, is based on a mathematical formula and is widely used throughout the southern United States. This rule allows for a saw kerf of 5/16 inch and a slabbing allowance of 4 inches, which is about twice the normal amount. Because of this, the Doyle Rule is somewhat inconsistent; it underestimates small logs and overestimates large logs. As a seller of timber, you must be aware that for smaller logs the Doyle Rule will underestimate the actual volume of wood that you have in your trees.

Scribner Log Rule

The Scribner Log Rule, developed around 1846, is a good example of a diagram rule. It was created by drawing the cross-sections of 1-inch boards within circles representing the end view of logs. A space of 1/4 inch was left between the boards to account for saw kerf. The Scribner Rule does not have an allowance for log taper and typically underestimates logs, particularly if the log length is long. The Scribner Decimal C is a different form of the Scribner Rule; it rounds the volumes to the nearest 10 board feet. For example, 392 board feet on the Scribner is equivalent to 390 board feet on the Scribner Decimal C scale.

International 1/4-Inch Log Rule


This rule was developed in 1906 and is based on a reasonably accurate mathematical formula. The rule allows for a 1/4-inch saw kerf and a fixed taper allowance of 1/2 inch per 4 feet of log length. Deductions are also allowed for shrinkage of boards and a slab thickness that varies with the log diameter. Overall, the International 1/4-Inch Log Rule is the most consistent and is often used as a basis of comparison for log rules.



Just call me the midget doctor.
Forestry Forum Founder and Chief Cook and Bottle Washer.

Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

ellmoe

   These are all just estimates of what a log will yield in sawn lumber. International gives higher numbers than Doyle for the smaller logs (the ones you will be cutting), somewhere up the scale (don't have them in front of me) they will converge. I believe scribner is in between. The important fact is to be aware of what scale is being used and the dollar value attached to it ( for example $200/mbf International is not the same as $200/mbf Doyle!). I believe you can find these scales on this site, if not, an internet search should locate them. I sure someone (probably Tom ;D, will come on before long and set you up. I just didn't want you to think that you were being ignored! :D

   Good luck.

Mark
Thirty plus years in the sawmill/millwork business. A sore back and arthritic fingers to prove it!

leweee

All you need to know about log scales is buy on the "doyle " sell on the "international".  ;)  :)
just another beaver with a chainsaw &  it's never so bad that it couldn't get worse.

Ron Wenrich

Most guys that buy on the Doyle, sell on the Doyle.  Very few people have the luxury of deciding which scale they will sell their logs.  A log or tree is worth just so much money.  When the volume changes, so does the dollar value. 

Rathbone

International will give you a pretty good idea of what you can saw out of that log.  And there ain't any stupid questions.   ;)
Never under estimate the power of stupid people in large groups.

extrapolate85

In the end, it generally best to use the scale method that is accepted in your part of the world. To learn more about log scaling methods go to: http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr01.pdf .

Good luck, not even experienced people have an easy time with log rules.  :-\       

Captain

Thanks for the history lesson, Jeff.

Might be intersting to calculate my over-run on Doyle sometime.

Captain

just_sawing

Ok Now how about the Ceader scale used in the South. Red Aromic Ceder has  a Scale to its self, Does anyone know where it can from?
You can follow me at
www.http://haneyfamilysawmill.com

rathbone

alright then, so the international 1/4 rule will probably be the most conssitant (and when I hear people refer to 4/ qtr, 5/qtr, 8/qtr Etc, I can assume they are refering to the international 1/4 rule, correct???).

Also what are the actual dimensions of, say, 4/4, 5/4, 8/4 Etc. ?  Again, I don't want to sound like I don't have a clue...but I really don't smiley_dizzy.  The more I delve into this sawing business thing, the more I realize how much I don't know, this forum is a huge help.

I'll check out the tool box here on the forum for the log rules.

I spoke with some tree services yesterday and some of them would be willing to sell their downers a small price, some maybe free if you haul them away for them, or even give to me for some lumber in exchange.

Thanks !!!
Rathbone

woodhick

Now first let say I don't want to hijack this thread into something else but since were talking scales there is something that really puts a bur under my saddle.  It's true the Doyle scale underestimates smaller logs, I've heard mostly the 16"-20" sizes.  Now where I come from almost all of the hardwoods being cut fall into this range.  So the buyer is making out a little on the scale already.  then throw in the fact that all these scales were designed around circle mills and big kerfs.  With the thin kerf bandmills of today there can be as much as a 30% overrun from the scale.  I have proven this with my bandmill.  so in the end the poor guy selling his logs is really taking a hit!  >:(   Sorry for the rant but this has bothered me all along.  I am sure the buyers are not going to go to a new scale for the bandmills because that cuts into there profits, so I guess will just have to live with it. >:(    RANT OFF, but it did feel better to get this off my chest :D.
Woodmizer LT40 Super 42hp Kubota, and more heavy iron woodworking equipment than I have room for.

ellmoe

Rathbone,
   4/4 = 1", 5/4 = 1 1/4". etc.

Woodhick,

   How is the log seller getting ripped off? If both parties agree on a scale or tonnage price where is the rip-off occurring? The same log can sell by Doyle, International, Schribner or even by the ton and the money be the same, however the price reflected on the scale is different. If I bought Milk for $1/half gallon or $.50 /quart where's the difference? Also, why should the log seller get more money for the same log if a band mill is sawing it versus a circle mill? How does that impact the value of the log? If it is because the band mill will yield more wood, fine. Then the log seller should reduce his price because the bandsaw is much slower at sawing  than the circle mill, so the cost of production is much higher. If someone is misrepresenting a critical element in a "deal" that is one thing, but if two informed parties agree to a price to buy and sell on, I don't see how a rip-off is occurring. Just my opnion. :)
Mark
Thirty plus years in the sawmill/millwork business. A sore back and arthritic fingers to prove it!

Ron Wenrich

rathbone

When you hear 4/qtr, etc, they are referring to the thickness of the lumber.  It has nothing to do with log scaling.  In hardwoods, 4/4-7/4 is normally cut 1/8" heavy.  For heavier stock, 1/4" heavy is the norm.  That can be different, depending on your customer base.  

woodhick

The International scale was originally formulated for 1/8" bandmills.  There was only one problem.  Using the 1/8" scale, you couldn't cut that out of the logs with the bandmills.  So, they went to the 1/4" scale.  

Overrun is dependent on a lot of different things.  One is cutting pattern.  If you're pulling big blocking versus cutting into 1" lumber, then you'll get more bf per log.  It makes no difference whether you're using  bandmill or a circle mill.  You may be getting 30% overrun in some logs, but you're not doing it on all your logs.  Try to use a log run average.

You also have to factor in that the price per Mbf is not the same for both scales.  Most guys will offer more $/Mbf for the Doyle scale than for the International scale.  That seems to me that the guys buying on the Int. scale are actually paying less for the better quality large logs than those buying at Doyle, since prices don't vary by diameter.  We have a sawlog comparison price calculator in the Forum Extras area.  You might want to check out the differentials.  
Never under estimate the power of stupid people in large groups.

logwalker

I've noticed that at the shootouts none of the mills made their scale. I don't know what scale they were using but I always thought that if you were carefull with a bandmill you could beat scale. WHat am I missing here? LW
Let's all be careful out there tomorrow. Lt40hd, 22' Kenworth Flatbed rollback dump, MM45B Mitsubishi trackhoe, Clark5000lb Forklift, Kubota L2850 tractor

simonmeridew

For a rule of thumb scale, one variation is a type of "Vermont Scale". I might use it is when I'm in the woods and wonder what a certain log might have in it.

For a 12 foot log, look at the small end. Take the diameter inside the bark, multiply this number in inches times the radius(half the diameter). This is the number of board feet.

For example: a 15 inch diameter log, 12 feet long. Diameter is 15 inches, radius is 7.5 inches. Multiply together to get 112.5 BF. For an 8 footer, since it's 2/3 the length of a 12 footer, multiply the BF by 2/3. That is multiply by 2 and then divide by 3.   I get 75 for an 8 footer.

For a 16 footer, since it's 4/3rds as long as a 12 footer, multiply the BF by 4/3.

Try it, you'll like it. Get the Forestry Forum toolbox up and try a couple of different sizes of logs using it against the International and Doyle.
Simonmeridew
Kubota L4400, Farmi 351

rathbone

Thanks Simon,  thats seems easy enough and thanks to Ron for clarifying the 4/4 vs log scaling issue.

Thx,
Rath

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