Rough-Sawn Thickness Versus Finished Thickness

or how to minimize thickness loss when they plane their rough lumber smooth. October 14, 2006

I sawed some red oak for an individual a year ago. I had sawn it 1" per his request and now he's complaining that he can't plane it to 3/4 clean – rather, he has to mill it to 11/16" before it meets his satisfaction. I used the 1" scale on the WM as I do for my own lumber. Granted the green boards are coming off the saw at about 15/16” and air drying to approximately 7/8". I'm using the .042 blades. Any suggestions how to deal with this situation?

Forum Responses
(Sawing and Drying Forum)
From contributor A:
On my Norwood mill, there are two scales (actually there are several). One is true inches - if I use that, I get as you did, 15/16ths lumber. If, on the other hand, I use the 1” board scale, the lumber comes off the saw a full 1” thick.

Unless your customer’s lumber is cupped some, he still should be able to get good 3/4 out of it. When sawing for a customer, I always make sure that I understand whether or not they want full inch cut, or just cut on 1 inch drops.

From contributor B:
You sawed it a year ago and he has had it all this time? You have no way of knowing how he stacked it or where. Are there other customers who complain about the same thing? If not, tell him to get a grip.

From Gene Wengert, technical advisor, Sawing and Drying Forum:
The rules of the NHLA are that the lumber must be at least 1.00" thick when it comes off the saw. If so, then it is called 4/4 or 1" lumber (hardwoods). If sold air-dried, it must also be at least 1.00" to call it 4/4. Most mills will target 1-1/16" green average size. If you sold this lumber at 15/16" green or 7/8" air-dried, then you were manufacturing and selling 3/4 lumber, not 4/4 or 1" lumber.

From contributor D:
I can tell you as a professional cabinetmaker, and hobby sawyer: 7/8 thick is enough to get 3/4 out of most of the stock - clean both sides, if it's flat or nearly so to begin with. When I buy rough lumber, I have the guy with the big two sided $40,000 planer take it to 15/16”. I finish it up at ¾” after rough planing with my planer and flattening with a jointer and planing the jointed side again. It takes some skill which only comes from practice at reading which side to take off stock from so you end up with the best side possible at the proper dimension. You did okay. You could have done better by giving him a full inch. He probably could have done better by stacking and planing/flattening.

From the original questioner:
To Gene Wengert: I didn't sell the individual any wood. What I did was saw his logs per his instruction at 1". He was afforded the opportunity to have it sawn either as 1" or thick inch and he chose the 1". I explained to him beforehand that the 1" would come off the saw slightly less than 1" and the thick inch would be 1-3/16". The individual worked with me on the saw and was satisfied with the wood at the time it was sawn. He stacked and dried it in his garage with an overhead gas furnace/hot air and fans. As to how he stickered the lumber I don't have a clue other than I cut him plenty of stickers. I'm going to go see him and the lumber tomorrow. I cut my own lumber for the most part at 1" and have no problem getting it down to 3/4" by carefully planing and working it off a little at a time. I'm wondering too if he's trying to plane wide boards with some cupping. I know he wanted it sawn wide so there may be some cupping that he doesn't know how to deal with.

From Dr. Gene Wengert, technical advisor, sawing and drying forum:
It sounds like the customer goofed. Incidentally, the shrinkage of lumber when drying is about 4% in thickness, which is just over 1/32". As many operations use ripped pieces of lumber that are 5" or less in width, maybe the customer is trying to clean up the wide pieces of lumber and the warp (due to poor drying practices?) will not let him.

From contributor G:
I don't mean this in a snotty way, but he requested 1" and you under sawed and gave him 15/16", so you messed up. The client may have been too ignorant of the process to make an educated call. It sounds like you only offered him a choice of 15/16" or 1-3/16" with nothing in between, so he chose the thinner. Setting your saw head on the one inch marks without compensating for the blade kerf is not considered sawing one inch lumber, but rather, as Gene said, you cut him 3/4" lumber. When I saw hardwood, I saw exactly at 1" only under duress from the client. When the client says "you're the pro, do as you see fit", I always cut to 1-1/8" so there is enough extra to compensate for drying loss. I've had many clients come back and thank me, saying sometimes even at that, they barely made 3/4 finished. In a perfect world, 7/8" can plane to 3/4", but this is a far from perfect world.

From the original questioner:
The guy I did the sawing for knew he was getting 15/16" off the saw and he acknowledged that yesterday. Secondly, he wanted the 15/16" so as to maximize the number of boards he could get from a log. Believe me, I explained the different thicknesses and the difference between quartersawn and flat. The problem wound up being that he had sold the air dried lumber to another individual and first, that individual didn't know how to use his old planer, and second - the cutter head is loose, with a problem with bearings or something. I told them both to get me one of the boards - any board - and I would plane it 3/4" finished. They handed me a 10" wide board with a good cup in it. The edge thickness of board measured .932. The first thing I did was split the board thru the center - thus 5" boards with no cupping. Then I went over to the planer, noted that there wasn't any scale, so I adjusted the head close to the board and started the board thru while cranking the head down until it contacted the board. I ran the board through a second time on this setting. Then I asked the guy who owned the planer, what the adjustment amount was for a full turn of the depth adjusting wheel, and his reply was “Darned if I know.” I figured out that a full turn was 1/8" cut, I asked him how much adjustment he was doing when he was planing.

Apparently once he got the cutter to touch the board he turned it a full turn, hence he took off the full 1/8", flipped the board and cranked it down another full turn. At this point he hadn't even considered the cupping on some of the boards and kept cutting until the boards were planed both sides smooth. Even without any cupping there was no way he was going to get 3/4" boards. He was starting with the assumption that the boards were 1" thick thus 1'-(2 X 1/8" )=3/4" which would be correct in theory or full 1" boards. But when you start with boards that are slightly over 7/8" (.932) and take off .125 per side or .250 he was finishing at .682 not .750 under the best of circumstances.

Throw in a loose cutter head and the associated board chatter and you get crap, and that is what I had to contend with. Believe me, I was a gentleman and bit my tongue a few times. Then the guy I had originally sawn for asked me to saw again this winter, and I told him sure but we're going to cut thicker and you’re not getting as many boards per log. Thanks for the responses guys.

From contributor E:
When I saw 1 inch boards they are 1 inch thick. On my softwood scale the blade is factored in so I produce 4/4 lumber. My hardwood scale produces lumber 1-1/8” thick for 4/4. When oak boards get wider then 10 inches the extra thickness is needed to plane out cup (wide boards do cup). So when I saw hardwood lumber for customers I always saw it 1-1/8” thick and some of you will say that I am wasting lumber. But look at it this way. If I had sawn it 1 inch thick then I would have had to make about 10 boards to gain 1. Most logs will lose grade by then. On large logs you will have to rip all of your wide boards to be able to plane them down. To me it is better to lose one board in the sawing then to lose several after they are planed and do not fit the need. Wider boards may cup more but they will bow less if centered on the pith.

From contributor F:
I had the same problem when I first got started with a guy using a Woodmizer on red oak. After running more than 10k bf I can tell you do not short cut the boards by sawing just 1" green. Some boards will clean up at 3/4" but most will not come close. We have found its best to saw 1-1/16" to 1-1/8" green and it gives us the best overall finish from the kiln to the final product. Trust me when I say we have dried a lot of lumber both ways and have dealt with trim and flooring makers as well as clock makers on this. They buy our lumber S3S 13/16" all the time, and also we use it in the shop to run custom trim orders. If it’s not there when it comes out of the kiln you can't put it back on. We had a load of 7" and wider FAS that came out 7/8" because the sawyer was trying to cut corners and save money. It wasn’t much savings for us when it wouldn't even clean up at less than 3/4".