Log Scales, Log Size, Kerf Thickness, Lumber Yield, and Profit

The estimated yield using one or another log scale may differ from the actual board footage of lumber sawn from a load of logs, for a variety of reasons. Here's a close look at how different scales, different logs, and different saws affect the yield, the price, and the profit. April 20, 2011

I have always found that my band mill produces much more from logs than Doyle, Scribner, and International log scales. I have been bound in a contract for the past two months on a logging job, and the time has finally come to start moving logs to my sawmill. The contract stated that everything would be tallied with Doyle Scale, and the forester has asked if I can just tally the board footage after sawmilling. I told the forester no because the board footage was contracted at Doyle scale, and running a bandmill is to my advantage vs. a circular mill.

I told the forester that the price would just be lowered per board foot to the equivalent in log form on Doyle scale, so the price would be the same, but I have always noticed that I drastically over produce lumber after reading log scales. I feel that a new updated scale should be produced, but this would put a wrench in the works and send a lot of loggers and mills in to confusion. Prices would probably only be adjusted, but in the long run people are having trouble left and right.

Forum Responses
(Sawing and Drying Forum)
From contributor E:
I'm glad I'm not the only one thinking things are wrong. But the scales must be made in favor of the sawyers who don’t cut properly and waste a lot. Or maybe they consider only the square out of the middle is the only good wood for lumber.

I cut the timber off my first farm and sold to the local log yard/mill (no real choice at the time). I always felt I was getting short sticked and questioned about getting docked on second and third cut logs when they were as clear as the butt cut, even if I took the first clear 24' and made two 12's. The second cut always got docked a grade(s). Didn't know who to question or report to.

I never thought it was right of them to gain the large percentage of extra footage per log. Yes I do understand that sometimes the log may have unseen stresses and internal flaws which is a risk of footage loss and it can't be measured exactly but a 5 % error/cushion is a long ways from 20-30% scaled under footage a logger/farmer gets paid for. Also a good buyer/grader knows 97% of the time what/how a log will saw just by looking at the log without any guessing.

From contributor C:
It’s true the Doyle scale does discount logs under 24''. My bandsaw gets a 1/3 more bd ft from a log than the scale says. I figured this was only from kerf loss due to the big saw. Most circ saws here are 3/8'' kerf. Doyle also doesn’t figure the side lumber just as you suppose, only the square cant in the middle. It works in my favor now too since I find myself buying some logs.

It may not be 100% accurate but it is what all buyers in my area use and I just make sure that I pay a little more to make my loggers want to bring their logs here. Being honest is a decision. You have to decide for yourself whether you will be or not.

From contributor B:
I think Doyle scale tends to devalue small logs because they take just as much overhead (time to buy, handle, process, waste to yield ratio) as a larger log yet yield much less lumber. I know on days when we saw mostly 10” logs, we’ll produce far less lumber than a day when we saw the same quality and length logs that are say 14”-20” dia.

Upper cut logs, although they may look as nice on the outside as a butt cut log they came from will often start to produce lower grade lumber much sooner than the butt cut. A good butt cut hardwood log will often produce high grade lumber all the way to the cob. If the butt cut log were made as long as possible and still retain high grade, then the lumber would still tend to grade high even thought there would be more defect in one end of some of the inner boards. The mill can make up in the small loss in grade on some boards by improving their production such as sawing one log say 16’ long vs. two 8’ logs.

All the scales were developed to reflect the yield with wide kerf circle and big band mills. A thin kerf bandmill will often produce 20% more lumber (when sawing thinner lumber) than a wide kerf mill will. When sawing things like rail road ties or heavy blocking, the “overrun” tends to equal out a bit between the mill designs.

Accuracy plays a part too. When we first stated sawing grade lumber, the buyer insisted that 4/4 be sawn a full 1-1/4” thick and was very skeptical of buying lumber produced on a thin kerf bandmill. Our current buyer specs a target of 1-1/8” for 4/4 and will accept down to 1” and are very pleased to get lumber sawn on a band mill.

It’s all relative. If we were to devise a scale that would be a more accurate indicator of what the log would yield, then we’d have to make adjustments in what we pay per board foot for specific logs to come out with the same profit or loss - as the case may be.

Some advocate creating a scale system for band mills that would accurately reflect the actual yield from logs sawn on a band mill. I’m opposed to that line of thinking. I see a log as a raw material that should have equal value regardless of mill design. I can’t compete with large circle mill operations in volume and production of common products. I can compete with the advantage of higher yield - especially in more valuable hardwoods and in specialty products.

This would be confusing for the logger also. Say he brought a load to a band mill and it scaled 3,500 bf total on a band mill scale. But he’d take the same load to a circle mill that still used Doyle and it scaled 3,000 bf. The “value” of the two loads would be the same regardless so the difference would have to be made in price per board foot.

From contributor A:
When you saw large number of logs from different suppliers you will run into bad logs and hidden defects. Who pays for this? Nine times out of ten the sawmill does. Yes my band mill may produce a bit more lumber but it also takes more time and the cost to produce per bdft is higher. The price would adjust no matter what scale you use. Each step of the process has to make some profit or there is no sense in being in business.

Over the years I have had people come in and tell me I was ripping them off by giving so little for their logs. So I offered to saw their logs and give them contacts to sell their lumber. When it is all said and done they come back and just sell me the logs. All have told me by the time they do all the extra work it is not worth the extra money. Yes red oak FAS maybe selling for $5.00 a bdft in the Box Store but it took a lot of work to get that board there.

It cost me $1.00 bdft to produce FAS red oak lumber for retail sale. I can buy it wholesale for $1.50 bdft and do not have to wait six months from the time I buy the log till I can sell the board. I do not have to handle all the other products to get the FAS. I can sell either for $2.25 bdft so which is the better deal for me?

From contributor P:
I really don’t think the thin kerf bandmill was invented to be able to rip off the logger. A new scale would cause a lot of confusion. If we bandmillers started buying by a scale that read more bd ft and paying less no one would bring us logs. When people call me I have never had one ask what scale I use but they always want to know the price.

The thin kerf bandmill does however allow people with a small investment to make some extra income sawing and even making their own lumber very economically and safely. The $5 bd ft box store red oak can easily be produced by a novice sawyer and save him some money on his own projects. I don’t think the bandmill manufacturers are trying to rip off the logger.

From Gene Wengert, forum technical advisor:
There are over 100 different log scales that try to estimate the footage. The three main ones in the USA are Doyle, Scribner and International 1/4 inch. Note that this last one specifies the saw kerf. With a 1/4" kerf, it is quite accurate. There is also an International 1/8" kerf which would be closer for folks with a band saw, but I have not seen it used.

Nevertheless, the Doyle scale works well, as stated, because it compensates for the extra handling of smaller logs but underestimating; it allows the same price per BF for any size log. A forester that suggests you pay based on your tally seems to be a bit off base to me. You would end up overpaying for small logs.

Note that the US Forest Service has sawn thousands of logs and has included the overrun using all three scales. For thinner kerf, you could easily (and quite accurately) just add 2-1/2% to the scale value for each 1/32" that your kerf is under 1/4". Of course, a large circle saw (52" - 60") often uses an F- or 2-1/2 style tooth which is 9/32", so they would subtract 2-1/2%. A chain saw mill might subtract even more. Another point is that the scale will be most accurate if the net scale is used, deducting for rot, shake, sweep, etc.

From contributor S:
I've heard more than my share of fussing over log scales and who is getting screwed. My standard answer is very simple: I pay the best I can for logs because I need good suppliers. It doesn't matter which scale I use, the amount of money I pay for a load of logs will be the same. There's only a certain amount of profit available, I have a good idea what it is going to be. If you want "good footage" I'll use international scale, but I'll still pay an amount for the logs that gives me a decent profit.

From contributor E:
In central PA, we typically use Scribner Log scale. Doyle greatly under scales small logs but over scales larger logs, International is fairly consistent for circular mills but allows great overage for band mills. Basically, we use Scribner because it is a happy medium. Also, many of us use Scribner instead of Scribner Decimal C because of the rounding issues.

To tell how close the scale is on using Scriber vs. sawing on a band saw, I recently purchase 3930 bf of logs with Scribner tally. I had four logs that turned out to be complete junk but the rest were great. With counting cants, dog boards and lumber sawn random width, I produced 4120 bf of material. The logs that were scaled and lost tallied 156 bf. If I think I will get exactly what I pay for out of a log and add the 156 bf to the finished product total, I would have 4276 bf with the purchase of 3930 bf of logs, a difference of 346 bf. This equates to approx 8% more lumber than I paid for.

This isn’t always the case. You will hear guys say they can beat the scale by 40-50%. This is true if you are buying smaller logs and sawing a lot of 4/4 lumber. In general, my experience has been if I buy on Doyle, I can beat the scale by approx 27%, buy on International 1/4 and I can beat the scale by approx 17% and Scribner on an average of 10%.

Personally, a logger might think he or she is being taken advantage of but does the logger tell the landowner that they took 50 trees more than they paid for? Does the logger give any more money to the landowner when a 30" red oak logs sells for veneer vs. an F1 log? Does the logger say much when he or she ends up with a curly maple or curly oak log that sells for 10x what the paid price was? Not likely. There have been a few times in my life where I have had this discussion with loggers and if they disagree with the scale, I put a log on the mill and say, "let’s see what we get". Normally it’s a completely different relationship after that moment and things operate very smooth. To each his own when it comes to doing business, but educating the customer and logger on what is doable and not drastically reduces problems in the long run.

From Gene Wengert, forum technical advisor:

Does anyone remember when the US Forest Service began to sell timber on the cubic foot basis with the intent of going to cubic meters? If we do eventually go this route that will mean each diameter log has a different price per cubic foot even if the length is the same.

Here is a comparison of the three scales, for 12' long logs, but recognize that sometimes Scribner is by 10 foot increments (Scribner Decimal C) and all the zeros are dropped (that is, 50 = 500 bf and 8 = 80 Bf).

8" dia. = 12 bf Doyle; 25 bf Int 1/4"; 20 bf Scribner
12" = 48; 70; 60
16" = 108; 130; 120
20" = 192; 210; 210
24" = 300; 310; 300

From contributor A:
Since I use band mills a few of the loggers thought I was cheating and should pay more for the logs. So I stopped buying the logs. They would bring in the load and scale them. Then we would mark the logs and number them. I would saw and record the results and then sell the rr ties and grade lumber. I got paid $250 mbdft for ties and lumber graded and the logger got all the extra. He had to come and haul the lumber. The logger owned all the rejects and fire wood.

You would have thought that with a good deal like that they would have been getting rich. I mean they had control of the whole deal and made all the profit. I just got paid for what I sawed. The most any logger did was three loads. After that they just wanted the check for the logs by weight.

I loved the deal and made the most money of all time. I did not have to eat the bad logs. I did not have to take a beating on grade because the logs sit too long in the woods during the summer because he went to cut hay for a week.

No matter what scale you use the price would be adjusted to cover the expense of operating the sawmill. The Grade buyers will adjust their cost as will everyone else. Red oak is $5.50 bdft in Home Depot and $0.85 bdft at the sawmill. The sawmill paid $0.35 bdft on Doyle scale for the logs and the products paid $0.17 bdft for 3B, $0.45 for ties and 2C and $0.85 for the FAS with an average of about $0.53 bdft paid to the sawmill which has an operating cost of $0.25 bdft plus the transporting of the products and waste removal so the profit margin of $0.03 is really setting the world on fire. A good mill can produce 50 mbdft a day here so if all goes well the sawmill will make a $1,500 profit for the day sawing 10 tt loads of logs a day with their $3 million investment. No wonder so many sell out for scrap steel prices and day trade stocks.