turning cants

[alanh]

As Ive mentioned before, I just bought a used LT 15, I`ve read hear and seen "real" miller operators occassionallly flipping or turning cants as they saw. I`m assuming this is to get straiter lumber. My question is, and I apologize if you guys have answered it before, How do you know that the cant requires this method, or should it be done on all.

[Larry]

Three reasons to flip cants.  The first is to keep the lumber at a consistent thickness.  You know its time to flip if you can see the ends or the middle raise off the bunks.  The second is when grade sawing.  Its time to flip when the face you are on starts to loose grade and another face shows more promise.  The third is to keep the pith in the center of a post or beam if that is what your after.

I sometimes flip for a couple of other reasons but they are not particullary important.

[Ox]

Larry nailed it. 

Think of it another way:  when you take a board off the log, it's releasing some tension that is present in all logs.  This released tension will let the log move a little or a lot.  You need to take a board off the other side of the log to compensate for this.  Clear as mud? 

[bkaimwood]

In many cases, IMO, to make the highest quality, best sawn lumber, a shim cut is needed after flipping to straighten the opposing side of the cant...as it has a slight hump or horn to it, which is why it was flipped in the first place, if you noted tension. I despise shim cuts as most do, as its lost product, waste, and costs time and money...I many times don't bother on low grade stuff unless it's BAD...

[terrifictimbersllc]

One turns a cant on account of stress, when one sees the ends or the middle lifting slightly (cant is bending).  On the other hand if the mill has a firm grip on the middle, with the clamp set low enough, and the ends or middle are not lifting, you can decide to  "go for it" by sawing all the way down to the bed.  It is a judgment call as to whether the stress will be so great that the cant will pop out of the clamping setup.  If it doesn't nothing is lost (as long as the ends don't lift).  But if they do slightly, you can flip after that board. 

What sometimes happens , usually with  skinny curvy hardwood logs, is that the cant pops out, or you forget and release it, then you have a bent cant that is too stiff to clamp flat again.  In this case you may lose a board getting it straight again.

Flipping the cant for grade sawing is a for different reason.

[Magicman]

Sometimes when I turn 180° I have to get the helper to stand on the cant and push it down for clamping.


 
Other times I may have to use this to pull the center of the cant down to the sawmill bed for clamping.

[bkaimwood]

Sometimes when I turn 180° I have to get the helper to stand on the cant and push it down for clamping.


 
Other times I may have to use this to pull the center of the cant down to the sawmill bed for clamping.

I've often wished I had a "helper" to stand on the cant, MM... But because that's rare, and when I do, they are skinny, thanks for a dependable helper idea...

[drobertson]

Everyone has summed it up,, stress is the reason for flipping I believe too,,  even when grade sawing I do flip, don't want thick and thin clear either, it is a give and take the way I see it.  I have a large block I use to beat down the center, after a light clamp I give a whack, hoping it goes down,  the c-clamps are a pretty good idea, very useful when needed I bet,

[Brucer]

Waiting until a cant starts to lift off the bed is leaving things a little late. You'll either have to waste some wood to true it up, or put up with a couple of boards that aren't uniform in thickness.

Once you've sawn a few logs of a particular species, you get a pretty good idea of how many inches you can saw off one side before it starts to bend. For example, I know from experience with Western Red Cedar I can get away with sawing 2" extra off one side of a cant without it lifting. So if I'm sawing 1" material I can saw 2 boards off one side, flip it 180°, and saw 4 boards off the other side (2 to restore the balance, plus another two before it starts to lift). With Birch or Aspen I have to flip every time.

Some species I can clamp in place and just saw right down to the bed (because the centre will try to lift, rather than the ends). I can always do this with Douglas-Fir and Larch. Sometimes with WRC, but I've had the odd one tear out of the clamp .

It's a matter of getting to know your wood.

[alanh]

Thanks guys, that there is a very clear explanation of why and when and what to look out for.

[Cazzhrdwd]

Most of the sawmill manufactures recommend against this but I've gotten used to moving the head up or down while sawing to compensate for stress if I need to stay on a particular side. I haven't made a waste cut in years. Sometimes I'll even grab the up/down pulley to spin it if I only need a slight movement, works great for me.

[4x4American]

 :P

[scmilling]

Just out thinking to myself, you band sawyers spend a lot of your cutting time dealing with tension. Why don't I get this with the lucas swing mill. Yes I'll frequently get boards that move as they're coming off, but a quick leveling cut afterwards taking off maybe an 1/8 of an inch is enough to level the face of the log ready for the next boards. Is it the fact that my logs aren't rigidly clamped that eases the problems?

[terrifictimbersllc]

It may be lessened to some extent by taking boards only part way across the surface not all the way like a band saw. The remaining heavy wood on the side probably restrains cant movement to some but not all extent.  However your 1/8" trimming is your responding to the same phenomenon.

And with a swing mill one doesn't cut down to the bed like a bandsaw so that the thickness of the last board would be affected.  All the material loss and movement is happening below the cut so at the end you get what you get and that's that.  If you're like me, in the end you quit when the holding wood falls apart and you are glad to escape the last cut alive.  :D

[Cazzhrdwd]

Just out thinking to myself, you band sawyers spend a lot of your cutting time dealing with tension. Why don't I get this with the lucas swing mill. Yes I'll frequently get boards that move as they're coming off, but a quick leveling cut afterwards taking off maybe an 1/8 of an inch is enough to level the face of the log ready for the next boards. Is it the fact that my logs aren't rigidly clamped that eases the problems?

I'm only dealing with stress because 95% of what I saw is 16'. You're probably sawing mostly 8'-10' just a guess though. In that case there is virtually no stress. Also, the 1/8" cut is all we're talking about, it can get worse if you don't flip it 180. That is why I've learned to move the head while I'm sawing. Its not the waste of the stress, its the time it takes saw it off and straighten it.

When I get all the FAS off, then I'll flip it 180 and bring the stress back down one board at a time until I get to my pallet dimension.

There is honestly no possible way I could get the footage done in a day with 16' logs if I had to saw off a small piece constantly. If I flipped it as one should to avoid the stress I'd have a lot more 1 and 2 common lumber.

Plus, suppose you saw off that small sliver to straighten it, you then saw a board and the can't starts going the other way. If you saw another board on that side its going to be too thin.

[scmilling]

No I try to avoid doing short length stuff on the lucas - too much time lost changing height.  Mostly do 16 18 and 20' lengths with the occasional 21'3" squeezed in with no room to move. The 1/8" levelling is done only as and when an issue starts to arise -literally!. Then not repeated until it starts to occur again , if at all. What I don't get is why the log itself doesn't behave in the same way with unclamped swingers as opposed to clamped bandsaws.

[Cazzhrdwd]

No I try to avoid doing short length stuff on the lucas - too much time lost changing height.  Mostly do 16 18 and 20' lengths with the occasional 21'3" squeezed in with no room to move. The 1/8" levelling is done only as and when an issue starts to arise -literally!. Then not repeated until it starts to occur again , if at all. What I don't get is why the log itself doesn't behave in the same way with unclamped swingers as opposed to clamped bandsaws.

The clamp doesn't help me, once its let go and the cant pops, I'm back with the same problem, besides if I have to clamp it to keep it from moving, I've gone too far anyway.

I would think you're sawing logs different than band mills or a species that may not stress as much. I have stress on just about every log over 12'.

[bkaimwood]

Just out thinking to myself, you band sawyers spend a lot of your cutting time dealing with tension. Why don't I get this with the lucas swing mill. Yes I'll frequently get boards that move as they're coming off, but a quick leveling cut afterwards taking off maybe an 1/8 of an inch is enough to level the face of the log ready for the next boards. Is it the fact that my logs aren't rigidly clamped that eases the problems?

You stating that you frequently get boards that move as they are coming off, and then saying you are taking an quick 1/8" shave off the log to make a flat surface again, to be ready for the next board, is a clear indicator that you ARE dealing with stress, seeing the same thing us bandsaw operators are seeing, and correcting accordingly... The only difference is the shape of the blade...I don't know if you can saw tension off the opposing side of the log to alleviate this issue, never ran that style mill. But if you could, I would. Seeing boards move as they come off means they already have stress in them, which was not releived... This means lumber that is not straight from the start, and potentially higher drying losses and defect, among other things...

[Ox]

With all the annoyances and aggravations associated with milling lumber it's a wonder we do any of it at all!  We must be relatively insane!  :D

[hacknchop]

 Remember just cause you read it on the net does not make it true or advisable.

[Percy]

With all the annoyances and aggravations associated with milling lumber it's a wonder we do any of it at all! We must be relatively insane!  :D

Yes, we are insane relatives ;D

[bkaimwood]

With all the annoyances and aggravations associated with milling lumber it's a wonder we do any of it at all! We must be relatively insane!  :D

Yes, we are insane relatives ;D

Duh...we are all sane, the 10%...everyone else is crazy!!! The 90%...:)