reading a log

I am running a small bandsaw mill for the winter and need advice. I have done some chainsaw milling for small projects, but now I need to produce 2x4s, 2x6s, and wide one inch boards. All the logs are 16 ft white or scotch pine with a small end diameter of 10 to 16 inches. Any tips on reading the log and planning out the cuts to increase yield and/or speed? Is there an advantage to quartersawing to increase your yield and production rate? I am happy to provide more details if that would help.

If you're milling 2X stock for structural framing use, quartersawing is the least preferable method. For one thing, it's significantly slower to mill that way - first of all you can't mill the whole log in one shot, and second you have to be constantly rotating the log to get the next best optimal cut. it's also impossible to mill a four-sided cant so that you can run off several boards the same size from a single cant without having to lift or turn anything. With a good bandmill you can even mill up a bunch of identical cants, put two or three back on the mill at the same time side-by-side, and cut off more than one board per pass. I've even done that with the Alaskan with success.

But the bigger problem is that quartersawing - especially in smaller-diameter logs like you're going to be working with - results in a lot of downgrading because of spike knots. Flatsawing produces round knots because the knots are perpendicular to the cut, rather than parallel as in quartersawing. A 1/2" round knot through the wide face only takes up 1/7th the cross-section of a 2X4 (true 2X4s are 1/5" X 3.5"). However in a quartersawn board, that 1/2" knot will take up 1/3rd the cross section of the piece. As such they are very damaging to the board's strength, and is why flatsawing generally produces the best structural lumber out of smaller-diameter logs. Flatsawn boards can be more prone to warping than quartersawn if attention isn't paid to grain runout (slope of grain). Ideally you want to be cutting parallel to the pith (center) of the log at all times, not parallel to the outer surface. It won't be a huge issue if you don't though unless the log has a significant amount of taper - just keep the boards properly stacked and stickered with plenty of weight to hold them straight as they dry. Otherwise you might end up with a few bananas on top of the pile!

Anyway here's a pic I drew up a while ago showing spike vs. round knots for another member asking a similar question:



The round knots are in the flatsawn stack at the top of the drawing, and you can see the difference in how much additional damage a spike knot of about the same size can do in a quartersawn piece. Knots of that proportion wouldn't be out of the question in a 10-16" Pine, either.

Also I scanned and uploaded my lumber grading training materials a while ago; you may be interested in reading through that. They're geared towards structural framing and 1-inch "common" (fence boards etc.) lumber and aren't much use beyond the basic concepts to someone grading furniture-quality hardwoods. You can find that PDF over HERE.

Wow, thanks for the great info. You confirmed what I was hinking about quartersawing, but I hadn't even thought about the issue with knots. I will rea the PDF right way. On my chainsaw milling I level up the log by looking at the center of the pith. On the band mill, we have just been dumping the log on the bunks and sawing away. Is it worth the time to level up the log on its central axis to try and limit the run out? Or is that too much effort for too little gain.

I would level the log. By level I mean if the log is 14 on the big end and 10 on the small raise the small 2 inches just eyeball it. The lumber you pull off the side will be stronger because the grain will run truer.
If you are sawing something crooked try to saw the cant to where the grain will run across the wide face instead of in and out.
I like to orient the knots where they will wind up on the corners of the cant. If the cant is sawed this way the knots will affect fewer boards. Knots oriented this way will be edged off lumber that comes off the sides of the cant and those boards are usually some of the highest grade on the log.

Good info, I just want to add quarter sawing is for hardwoods, and softwoods should be treated as a tube that you want to square up. If you can only take two stacks of boards out of the log, stop and rethink how you are taking them out of the log. By splitting the log in half, both stacks will have crook in them. Position your cuts so that you take off a couple of jacket boards and a single stack of boards and they will all be straighter in the end. If the log is large enough to get a triple stack with a couple of jacket boards, that is like having a single stack and the stresses of the wood will be contained.
I hope that is a bit clearer then mud. The guy that I am training on my mill is stuck on milling hardwoods and has a real hard time adjusting to milling softwoods.

:agree2::agree2:

What they said! Those fellas (and many others) have a lot more sawing experience than I do; I'm a graderman by trade so a lot of the theory overlaps, but I've only sawn a few dozen logs with the Alaskan myself so far. I used to run a fixed-set Chip-N-Saw small log canter at a sawmill until a year ago; not much real sawing experience to be had there though since it didn't matter what size of log went into the mill, the same 4X6 cant came out the other end.

OK I drew some pics of what I think Backwoods is saying.

First, what he is NOT recommending, which is "splitting" the log:



Boards cut like this nearer to the center of the log have a much different amount of stress on them from one side to the other as you move toward the pith. As they dry (or even as they're being cut) they can spring and warp as this tension is released. Also, lumber cut like this is still subject to spike knots in the center pieces and large three-face knots on the remainder. Cutting like this produces a lot of "riftsawn" lumber. This is useful for things like square posts because it results in nice, straight edge grain on all four faces of the piece rather than two faces of edge grain and two faces of flat or cathedral grain.

This is a single-stack cut:



First, cut the waste slabs and jacket boards off the sides. These are cut as rough flitches and must be run through an edger later to square and split if necessary. After the jacket boards and first top cut are gone you have a nice 3-sided cant that you can just start taking slabs off of from the top down. With a good bandmill you often don't even have to offbear the slabs after every pass, and can just keep working down until the whole thing is cut up. Pieces cut like this should be much more stable because the stresses are more even from one side to the other. All but the very center couple pieces will be flatsawn or slightly riftsawn.

And a triple stack:



You won't run into this if you're sticking to ~16" logs, but as Backwoods said this is much the same as a single stack - the middle stack absorbs most of the stresses just like a single stack would, and the outer stacks are in less reactive wood to begin with. This layout produces a decent mix of flat, rift, and quarter-sawn lumber. If the log is big enough, spike knots are generally not as much of a concern in the outer parts of the log, so it can still yield a good number of high-grade pieces.

Backwoods, feel free to chew me out if I messed up on anything here. As I said a lot of my input here is based on grading training and watching other sawyers by the hour, so I might have misunderstood what you meant.

Wow....this is why I hire a sawyer when I get a good big hardwood log. I tell him what I want and get it. Way too much knowledge with experience.

Thanks Brmorgan.
That is what i was trying to say. The picture show it better though.

Backwoods and Bmorgan, thank you for the detailed explanation.

If I ever get a bandmill ......:your tips will come in handy.

Thanks for the coaching. I've been thinking one or two boards at a time, and this will really help me progress. My boss is going to wonder what happened to me over weekend.

I take a tape measure and a wood crayon and rough out the patterns so that the customer can keep up with where the next cuts will be coming from, this may help you as you turn the log to stay oriented in the same sequence all the way thru the process.

Great info gentlemen - thanks to all of you!

Sawed any? Did the advice help? Lets see some pics of your setup.

The tips, info, and coaching everyone provided has been great. I have been sawing, but I probably won't get to take any pics because we're always hurrying. The guy I'm working for doesn't believe in lunch either. I'm only working till about 1 or 2pm so I don't waste away, though. The mill is a basic portable bandsaw with manual everything except a winch to raise and lower the cutting height. We load the log, decide on a plan to cut, and then I mostly operate by myself. Today I was cutting 7/8"x10" boards but mostly it's 2x4s, 2x6s, and 1"x10" boards. Everything is 16 feet long. The mill is alot faster than my chainsaw mill, but it still takes a lot of work to process a 16 foot log. I wonder what the next step up is like?

brisawyer said:

Sawed any? Did the advice help? Lets see some pics of your setup.

Click to expand...

I'm new to this forum and certainly enjoying all the info here. Thought it was about time I chime in a bit and at least say thanks for sharing the great ideas.

Did a bit of milling back in the 70's as a kid growing up in Minnesota. A friend operated an old large circular mill back on their farm. I've also hired a local sawyer a few years back who operated a Mobile Dimensions rig. My lumber stock pile from that time is nearly depleted now.

Last week I placed an order and deposit on a Norwood MX34 as a portable unit (including extensions to cut to 25'). We've got a fairly large woodlot here in WA with lots of DF and WRC, with the need for numerous outbuildings I'm planning to build in the near term...working on the designs now.

Now that I'm retired from working all over the globe, I've got the time and energy to mill for our own needs. Truly looking forward to it as well.

So, at this time don't have any photos of a mill setup to show you, but will soon. Grew up with a chainsaw in my hands and currently have several Huskies I've been using the last 10 years on our 110ac of trees here.

I have to search around this forum a bit more to find usable mods for the MX34 or similar bandmill. I know there are a few things I'll want to add straight away to the mill. I've been welding as a useful hobbie since I was 12 yrs old, so metal work is fun for me these days. Since my retirement fun also includes making hay on our 30ac of grassland, we've got a couple of tractors (60hp and 30hp Kubotas) with loaders and forks, wagons, etc which we've been using for log handling.

As a start, currently have 25+ nice sized logs from recent blowdowns my sons and I recovered from our woods during the recent holidays, which are now out in the field just waiting for a mill.

Again, thanks to everyone for sharing their knowledge and interest in milling. I hope to be able to contribute in someway as time goes on.

BTH

Wilson_tree said:

I wonder what the next step up is like?

Click to expand...

"Sweet"