Chasing perfection?

[JRWoodchuck]

Just curious how close to perfection your mills get? While milling dimensional lumber are you guys with 1/32 of perfect? and 1/8? + or -.  I have a home built mill and curious what is actually achievable. I saw some one post the other day that even the $30,000 mill aren't perfect if you want perfect get a planer. So it just made me wonder. Thanks!

[Magicman]

As far as the sawmill's accuracy, I can not measure any difference between "Setworks" sawn boards.  I often have customers that will try, and I just laugh.

Now that is sawmill accuracy.  A cant moving as stress is relieved will take you to task.   

[drobertson]

Logs move, set works hit the numbers, logs/cants move, it's green stock. Many factors can control timbers on the mill, but slight variations should be expected,

[bandmiller2]

Its called rough cut lumber for a reason. With good logs sharp well set band/saw 1/32 is practical with some care from the sawyer. Real world expect a little more, but that's no excuse for sloppy milling. Frank C.

[Brad_bb]

I think you are more asking about repeatability than accuracy?  My Woodmizer LT15 is very repeatable.  With clear wood, they are very repeatable.  Hard knots can cause a wave when you are milling.  Sharp band and going slow will help.  But if you don't see it ahead of time, you'll make a wave.  The beam planer really comes in handy there.  If I get a wave while milling, I simply run the planer head over it to flatten that cut face.  Then continue sawing.  Accuracy to me means how do the boards come out compared to the scale on your mill.  To tell the truth i haven't every done an truly scientific experiment to evaluate this.  I know it's pretty darn close.  I always planning to plane to dimension anyway.

[Magicman]

My mind went to framing lumber when the OP stated "dimensional lumber".  That is about the only lumber that I saw that is used as it comes off of the sawmill.  No sizing or surfacing.  Accuracy = uniformity.

[scully]

Repeatable accuracy is no problem on my mill . As stated before stress in a cant will indeed affect dimension .

[lyle niemi]

rough lumber is rough lumber,  I get my lumber very close on the most part but never perfect, you want perfect , get a planer

[kensfarm]

I've checked w/ the tape measure.. but never have taken the Caliper out to check.   
Could be interesting..
 

 

[longtime lurker]

I expect accuracy of +/- 1 mm.
I'll settle for +/- 1.5mm (about 1/16" )
If 3 boards in a row come off with a 3mm variation I go looking for a fault.

Log stress and cant movement are only issues if you want an excuse. I've built a business on the supply of straight dimensionally accurate GOS lumber cutting some of the toughest species in the world: inability to deal with log stress is an equipment and sawing pattern failure, nothing more, nothing less.

But as stated above, if you want perfect get a planer. My planer just gets an easier ride then most.

[WV Sawmiller]

LL,

   Please update your profile with your equipment used if you don't mind. I am interested in what kind of equipment you use to get this kind of performance. I'm like Lynn and get good repeatability using my setworks but I do have occasional issues with the stress causing a less perfect board. In my case I am depending on the weight of the cant to hold it down while other mills have teeth to hold the cant down better. The board/flitch may jump off when cut but still stays the same thickness.

[Magicman]

I saw many Mbf of framing lumber for homes each year.  I have one now that reported back to me Monday that he will have no building permit restrictions/issues regarding using "rough sawn" so felling and skidding is his next job.

There will be no planeing or resizing so consistency is a requirement when your lumber will be used for home building. 

[derhntr]

Once and a while I will get a thin or thick board when using accuset. Normally last boards off of cant. Could be stress, or got busy and forgot to clean sawdust off battery box or sawdust under cant. Dry mast rails or sawdust caught in the up down chain will cause jerky drop and effect thickness.

[Gearbox]

All the lumber on the circle mill I run goes through the planer . Therefor I get lazy end to end will be within a 1/16 . size will vary up to an 1/8 . Any thing over 1 3/4 will plane out to 1 5/8 . I can do better but it will affect production .

[Rougespear]

Ya, I'd say 1/16" is more practical, but a 1/32" is achievable... logs move, sometimes unpredictably.  Typically there is always a more "critical" dimension (eg. the 4" width of a framing member is more important than is 2" thickness), so try to get that critical dimension close.

I've been a finish carpenter on many jobs were the walls were about as straight as a drunk's driving... and that was using kiln-dried lumber.  So I agree with Lynn that sawmill repeatability yields consistent lumber, but people have done far worse starting with much better framing-wise.

[Joe Hillmann]

I have a homemade mill and my height adjustment is controlled by a winch with stops so each click is around 1/16 so I can't get closer than that.  When I am actually cutting I consider it good enough if the blade doesn't wander more than 1/16 above or below where it is supposed to be.  To get more accurate I would have to replace my winch with a worm gear winch or replace the cables with lead screws.  I could also be more careful when setting up the mill to make sure it is all perfectly level and on the same plane,  I use a cheap 4 foot level and am not sure just how accurate it is over the length of the mill.  At the moment I don't see the need to make it more accurate,  in the future I may come across a project that needs more accuracy and then I will see what I can do to make it better.

I sawed for one person how also had a pile of lumber stacked sitting there that was sawn on a woodmizer and by the looks of it the operator of the woodmizer either didn't know or care how to cut straight lumber.  It was full of waves and different thicknesses and made the lumber I made look really good in comparison.

[JRWoodchuck]

Thanks for all the responses. Was more curious per board variation than repetition. I would say my good boards that I produce are + or - an 1/8" which is ok for what I am using it for at the moment. But was curious what other people label acceptable.

[Magicman]

my good boards that I produce are + or - an 1/8"

An eighth of an inch would not be acceptable to either me or my customers because I only do custom sawing.

[pinefeller]

you can saw perfect lumber all day but a 12 wide pine board can shrink half an inch or more depending on the moisture content and even the ring count. with that said my saw works off dogged sizes so i can repeatedly make the same thickness boards over and over, however that system has its flaws too.  i shoot for 1/16'' and no waves

[D6c]

My older LT40 always seemed to cut a little thin using the aluminum scale it came with.  I started checking and the scale was made with a 1/6" allowance for kerf.....not enough.
I turned it over and made new engravings that allow for .100"  That should be closer but I haven't sawed enough to check it yet.
I also made up a scale with markings for dimensional lumber.