Newbie Looking for help on best way to slice and dice a log for beams

[Stuart Caruk]

I recently acquired a new Woodmizer LT35Hyd bandmill, and my wife and I took the training class at the distributors. We've found it remarkably simple to mill out siding and large beams. I own and run a large CNC machine shop so we have forklifts Cranes and Skidsteers to make life easy. My trusty Kubota KX-161 with a thumb does a pretty good job of getting the logs to the mill as well.

I need a bunch of smallish beams in the 3" x 10" size about 20' long. A 165' tall fir just happened to blow over in the last wind storm providing the ideal donor tree. I've got some 24" - 28" diameter logs to work with. Getting them on the mill is easy enough, but I've been scratching my head trying to figure out the best way to plan the cuts to maximize the number of 3" x 10" beams I can get from the log, with the least amount of fiddle farting around moving cants back and forth.

I've drawn up a bunch of scenarios in a CAD program and still end up not sure of the best way to tackle this project. I'm hoping someone with more experience can give me a suggestion.

Surely in this day and age there is an app, or a diagram that show how to best slice and dice a log from an end view....

Thanks for the help,

Stu

[coppolajc10]

Hi Stuart Caruk and Merry Christmas.  I'm by no means an expert and have less than a year of experience, but here's how I would look at it. My goal would be to get a cant that is 10" on one side and the other side to to have the most multiple of 3" as possible, taking into account the kerf of your bands.  For example, if the small end is 24", you will probably get at least a 10"x18 5/16" cant (assuming a 1/16 kerf, my kerf is usually more like a 3/32) with  no wane depending on straightness of the log.  As you're working down to this size cant you should get a lot of side lumber and many of it can be made 3" thick and edged to 10".  I would try to get the pith centered into one of the beams, and personally I would try to level the pith when I saw this out.  there are other considerations depending on what the beams will be used for, but this would be my basic approach.  Good luck, hope to see some pics, Jake.

[hunz]

The best way to go about getting the best beam yield from a tree goes like this in my book..... I cut side lumber until you end up with the largest possible can't from your log. A tape measure with measurements on the small diameter end can help aid when making the cut on each face, and defend in over slabbing one side too much.
  Once you have your large cant, determine how big it is, say its 13"x10". This will actually yield you (4) 3"x10"s negating kerf, if you take the first top beam off first. Depending on your use, I am a fan of cutting oversize then air stack to final dimension later.

  When you get to needing 5 different beam sizes, and try to maximize yield from each log, it can be a little more difficult to play "piece the puzzle" together. A crayon can come in handy in these situations. Sorry I couldn't give you a video or picture, it can be a little difficult to portray a physical process through words.


Enjoy that lt-35! I sawed about 800 bd/ft with mine today!

[Dave Shepard]

I've cut a lot of thick, wide planking in the past. If milling a fairly large log, I would open up the first face, and take a few boards, or until I could get a 3" flitch that was wide enough to make a 10" plank. Slide that down onto the loader arms. Then I would rotate 180° and set my setworks to make a series of boards and flitches leaving a 10" thick cant. Without Accuset, you will have to figure that out on paper, of just plan on having to take a cleanup cut at some point. You don't have to take all the boards and flitches off of each face, in fact I wouldn't to lessen the movement of the cant. Rotate 90° repeat step one. As soon as you can get that 3"x10" flitch, you take one or two. Rotate 180°and again open up the face. At this point, you need to figure out what face to saw down to 10". Once you have a 10" thick cant, then you work back and forth on the two adjacent faces taking off 3"x10" planks. I don't know how fir behaves. You might be able to just saw the whole cant right down to the bed. If it moves on you, then take a plank off, then flip 180° and take another, and then flip back. Once the log is sawn, then you need to edge all the flitches on the loading arms. It's hard to describe in writing.

[FarmingSawyer]

You could take some of the larger logs and plan for a 20-1/8" x 19" cant or so. Then figure slice a bunch of 3" slabs, set them off on the loader arm and then re-saw them a few at a time into 2 10"-ers. Draw it out on the small end, so you can see where a 10" slab will work and figure on either boxing the heart of taking it out in a low-grade 2x or 1x board. If you can do it, there's no point in whittling down a large log into 1 10" cant. And the more edging you can reduce the better.

Fir is pretty stable, but I've seen a 2x12 come flying off of a log with some tremendous force. Just depends on how the tree grew. IF you see movement, then you'll have to rotate the log to reduce stress.

[Chuck White]

Welcome to the Forestry Forum, Stuart Caruk.

[bandmiller2]

Welcome Stu, Your a man that is used to working with precision, CAD, and programs that work out as planned. Cutting logs all that goes out the window, the least little sweep will flush your best laid plans, you will always get less than you figured. What Dave says is probably the way I would attack the log. If your not too fussy about a spot of bark here and there you can get a lot more from a log. Frank C.

[Magicman]

Looks like you are covered on the sawing, so Welcome to the Forestry Forum, Stuart Caruk.   8)

[Warren]

I've cut a lot of thick, wide planking in the past. If milling a fairly large log, I would open up the first face, and take a few boards, or until I could get a 3" flitch that was wide enough to make a 10" plank. Slide that down onto the loader arms. Then I would rotate 180° and set my setworks to make a series of boards and flitches leaving a 10" thick cant. Without Accuset, you will have to figure that out on paper, of just plan on having to take a cleanup cut at some point. You don't have to take all the boards and flitches off of each face, in fact I wouldn't to lessen the movement of the cant. Rotate 90° repeat step one. As soon as you can get that 3"x10" flitch, you take one or two. Rotate 180°and again open up the face. At this point, you need to figure out what face to saw down to 10". Once you have a 10" thick cant, then you work back and forth on the two adjacent faces taking off 3"x10" planks. I don't know how fir behaves. You might be able to just saw the whole cant right down to the bed. If it moves on you, then take a plank off, then flip 180° and take another, and then flip back. Once the log is sawn, then you need to edge all the flitches on the loading arms. It's hard to describe in writing.

Hard to describe in writing.  But this is pretty sound advice.  I sawed out a stack of 2x10x20 and 2x12x18 rafters for a friend a couple months ago.  He supplied the logs. If you keep turning as you take off the log, when you find unexpected knots or voids, you can work your way around them. On a couple of the logs I sawed, found a pocket of ants and had to change the face that I was taking the rafters off of to minimize wastage.  Good luck !

[Stuart Caruk]

Thanks for the tips guys. I'm just finishing up my last set of saw guides for one of the local mills. The year end is always hectic as companies try to spend their available capital budgets. I'll be finished up by Tuesday though, so my plan is to try a few different strategies on a few different logs and see what works out the best.

There is a local sawyer who runs a couple Wood-Mizer saws and he has plenty of experience as he runs a sawmill full time and does pretty well by the looks of it. Even made the magazine as one of the top companies.

I figure like everything else though, the best way to learn something is to figure out the theory and then practice, practice, practice.

I do a lot of work for the local mills making several sets of sawguides a year, mostly for the steerable gang saws; Saw tension analyzers, and various custom products needed around the m,ill. The filers have been a wonderful source of help, but they run on a totally different scale than I ever plan to. Still, having my own mill has already proven to be a huge benefit.

Thanks for all the help and advice. I'll even try to get some pictures posted.

[bandmiller2]

Stu, what in ell is a saw tension analyzer, is that a special straight edge to measure tension.?? Milling is quite simple its like learning to ride a bicycle, you just have to do it, once in a wile you will take a toss. Start slow, form safe habits and check where the log backstops are before each cut, speed will come on its own schedule. Frank C.

[customsawyer]

You could take some of the larger logs and plan for a 20-1/8" x 19" cant or so. Then figure slice a bunch of 3" slabs, set them off on the loader arm and then re-saw them a few at a time into 2 10"-ers.

Keep in mind if you do it this way they will likely bow on you. Any time you split the middle of a log or the middle of a fletch from the side of a log it will tend to bow. ;)

[Stuart Caruk]

It's kind of off topic, but Frank the Saw Tension Analyzer is a device that we designed and build, used to measure the tension in a round saw blade. In the large mills filers build in tension into a saw blade so that it runs stable when it is cutting. On a band saw at say a Weyerhaeuser mill,  each tooth on a band mill cutting into the log experiences about 50 pounds of force. If the blade wasn't tensioned, the tooth side would stretch and the blade would want to twist snaking around as it cuts. They tension the blade by stretching the backside so that it cuts in a stable fashion. A round saw functions the exact same way. Think of it as a bandsaw wrapped around a central point. They stretch the inside of the blade to tension it. This allows them to use a thinner plate to build the saw and run them at a higher rim speed without snaking.

The old time filers would hammer the tension into the blades on a chilled faced anvil. Mostly now they roll tension on a device that works like a small English wheel. Every mill has what they consider a perfectly tuned embedded saw. It has the correct amount of tension, and they know this by how accurately it cuts the lumber. the filers try to put up saws to match this embedded saw, but until now there has been no absolute way to compare the tension. They could come close (or not).

Our STA allows you to mount an embedded saw, ring it out and view the nodal harmonic frequency values that the saw rings at. It's then a simple task to mount the saw you want to compare to it and see if it is under tensioned, bang on, or excessively tensioned. Essentially it works as an electronic Go / No Go gauge.

The mills are driven by recovery. The more log they can turn into usable lumber, the more profitable they will be. They design the mill to cut a specific plank size that will then clean up to make the highest grade dimensional lumber. We've seen demonstrated results where a properly tensioned set of blades reduces snaking from 3 - 11% depending on the mill and how good a job the filers did without the STA. When you consider that most of the mills are running .020" per side kerf clearances, that's a.001 - .004 reduction in kerf, making it easier to hit their board target.

It just another tool that we provide them. Our saw guides are made like we build aerospace parts, so we hold tolerances in the .0002" range where some of our competitors shoot for .005".  The inherent accuracy of our product has allowed the mills that use our guides to reduce their board targets as much as .040" and still get a plank that cleans up to make the best quality lumber. That doesn't seem like a lot, but in a really high production mill, a reduction of around .007" in board target gains them a wee bit over a million bucks in extra useable lumber over the course of a year. Save .040" here, another .004" there.... pretty soon it adds up to some serious $$$.