Yield?

[djg james]

I might have posted this here before or it might be on another site.
I'm considering having a couple of small logs milled and I was wanting to know, on the average, what % of a log's volume actually results in usable (furniture grade) lumber. I can calculate a log's volume to xx BF, but how many BF really can you expect? I know there's losses due to bark on the first cut and pith toward the center. 80% recoverable? 70%?

 

[BobL]

This is a how long is a piece of string question.
Most people compare "dressed and ready" lumber as they would buy from a store with what they see sitting in a tree trunk which leads to grossly misleading overestimates of yield.

So the following are some of the factors that will kick in.
What type of tree are we referring too?
What size lumber do you want?
What do you plan to use it for? OK you said furniture but does that mean you want all clear grain and zero cracks etc or are you prepared to "go a bit rustic"?
What condition, puke, knots, is the log straight or bent, under tension etc
What are you using to mill with, CS or BS?
How straight are you cutting?
How rough are you cutting?
What grade lumber do you want?
How good are your log storage conditions? This is where major losses can occur.
Unless you plan well ahead (even years) and cut close to required size, re-sawing and dressing to size can also waste a lot of wood.

Under the best conditions and if you need lost of or are are prepared to use/join, small pieces you could get 80%, worst case would be zero.
Its really difficult to even determine an average but I consider myself lucky if I get 60% of actual product (dressed timber useful to make a piece of furniture ) out of the stuff I mill. Admittedly its not all premium millable logs.
Even when know what sizes I want I typically cut twice as much as what I need to be sure I have enough to complete the job, This also allows for a little bit of selection ie straightness (or correction thereof) and consistency, etc

 

[djg james]

This is a how long is a piece of string question.
Most people compare "dressed and ready" lumber as they would buy from a store with what they see sitting in a tree trunk which leads to grossly misleading overestimates of yield.

So the following are some of the factors that will kick in.
What type of tree are we referring too?
What size lumber do you want?
What do you plan to use it for? OK you said furniture but does that mean you want all clear grain and zero cracks etc or are you prepared to "go a bit rustic"?
What condition, puke, knots, is the log straight or bent, under tension etc
What are you using to mill with, CS or BS?
How straight are you cutting?
How rough are you cutting?
What grade lumber do you want?
How good are your log storage conditions? This is where major losses can occur.
Unless you plan well ahead (even years) and cut close to required size, re-sawing and dressing to size can also waste a lot of wood.

Under the best conditions and if you need lost of or are are prepared to use/join, small pieces you could get 80%, worst case would be zero.
Its really difficult to even determine an average but I consider myself lucky if I get 60% of actual product (dressed timber useful to make a piece of furniture ) out of the stuff I mill. Admittedly its not all premium millable logs.
Even when know what sizes I want I typically cut twice as much as what I need to be sure I have enough to complete the job, This also allows for a little bit of selection ie straightness (or correction thereof) and consistency, etc

Thanks for your detailed reply. Let me clarify a bit. I get firewood logs from a arborist log yard so most are small 5'-6' long. This is about all I can haul in my small trailer weight-wise. Diameter of a couple of logs is 16" on one 22" on two others. I'm trying to decide if what I will get back in lumber is worth the cost of having them milling. I worked a a mill so I know what to look for in a log. Not an expert though so there might be surprised when I open them up. None of these logs have any rot or punk, branches or cats eyes and are fairly straight. I know the yield loss on smaller logs is greater and usually the pith lumber is unusable.

These will be sawn on a BS mill and I'm looking for a fairly high quality of lumber. I looking for an approximate BF of lumber from each log so I can figure approximate $/BF. I've stickered and AD a lot of lumber and with my own, I cut fresh ends, dip in wax and sticker under a cover.

 

[Franny K]

If you have a smart phone there are a few sawmill calculator aps. Sawlogcalc personal is the name for one I found. That one allows using a few different scales. Modify the result if you do not wish to count the center square like 4x4. There are other calculators on line.

Stuff growing straight up in a forest crowded on the sides likely will have the least distortion in curing. Short stuff won't really move as milling continues.

If you are asking for a ratio by weight of finished product to sticker and age vs dust, scrap, mulch etc 70% would be too high most likely in my estimation.

 

[djg james]

I just brought home a small 16" dia. x 5' Pecan log that is pretty clear. Calculations 45 BF. So I'm guessing realistically I'd get 25 BF of 4/4 x 6", 8" small project lumber out of it. Probably not worth the cost of milling, but I might take it along in case I need something to fill up my hour I'd be charged for.