sawing Problem

oregonsawer · December 29, 2010, 04:46:44 PM

My saw started sawing the last two one inch boards thick and thin
about two ft. from the end.
If seams to pick it up as it saw through.
I have done a complete realinement.
The ban is right on plane.

It will saw 5/4and 8/4 real well.
Can any of you guys give me a place to start?
Thank you.

terrifictimbersllc · December 29, 2010, 04:52:18 PM

Both ends fully supported underneath?

Tom · December 29, 2010, 05:14:42 PM

That is usually a support problem. If the band has a tendency to climb in the cut, an unsupported, thin, cant (like the last cut) will force the 1x on the bottom down and the bottom board will be thick and the top board will be thin.

About the only way to combat this, other than your alignment-setup being absolutely perfect, is to move the cant so that the end is supported over a bunk/bed-rail.

Climbing in the cut, or diving, either one, can be an alignment problem, but can also be a gumming of the band or a miss-set of one side of the band.

Brucer · December 29, 2010, 06:07:53 PM

Another possibility ... if your board still has some stress in it, cutting it up the middle will relieve the stresses. As you get to one end, the board tends to curl up (or down).

It's easy to check for this -- as soon as the board starts to lift (or sink), stop the blade and back the saw out. Does the board stay off the supports? Then it's probably a stress issue. Does the board lie flat again? Then Tom's given you the answer.

oregonsawer · December 29, 2010, 06:20:49 PM

I have checked the alignment several times and every thing is right on.
And yes it has suport.
the then board is on the bottom.
And I have new woodmizer bads 10 degree.
sawing cedar and dug fir.
I don't understand it is a weard deal.

Chuck White · December 29, 2010, 06:29:21 PM

If the ends of the cant are supported, it would have to be stress in the cant.

If you're flat-sawing, try leaving the last 4-5 boards on top to support the final cut and see what happens.

REASONING; If the bottom board is thin at the far end, it has to be lifting up and therefore, weight should hold it in place.

tyb525 · December 29, 2010, 06:30:38 PM

Could it be that the rails your head rides on are worn, and the stuff you are currently cutting is slightly longer than normal, so the mill head travels onto a less-worn (and higher) section of rail towards the end of the board?

gator gar · December 29, 2010, 07:38:28 PM

I'd keep the heart of the cant in the center at all times. Take a couple cuts and roll the cant 180 degrees. take a couple more cuts and roll it again. You'll cut the stress out of the cant, if there is some in there.

KingTimber · December 31, 2010, 01:41:16 PM

Thats a tough one.
If it is not blade alignment and you have the cant supported, then that leaves wear or debris on the rails and the whole head rig is riding up or down. The only other thing is tension in the log. Once I get a cant squared up and locked in I leave it alone until I have cut it to the bottom. This gives me the most accurate lumber possible. Wood is alive until you turn it into ashes. The only doug fir I have cut was recycled telephone poles. But white fir can do some crazy stuff. I was cutting 2x6 once, it pulled up about 3 inches then back down, started to hump in the middle, then it broke and jumped completly off the mill before I sawed out through the end. This is no lie. Side hill timber can cause alot of this type of action and wood that has dried out alot. Small hardwoods give me this type of problems at times. My mill has a chain turner. I have taken my dogs and actually pulled down on the cant with them. Stopped my cut, put up the turner and used a tooth on it to pull down on the cant while I moved the dogs out of the way. Cut past the first dog then clamped it down again. Moved the roller and continued on to repeat the process for the second dog. Mother Nature and I have an understanding, she can kick my ass any time she wants. If I saw in and get a rise in the cant so my next cut is going to come out thick, I recut at that same height and cut off the wedge. This is why man invented the planer.
Good luck and remember a crooked log makes crooked lumber thats just how it is.

northwoods1 · December 31, 2010, 02:16:17 PM

kingtimber you should post more often I know I could learn a lot

west penn · December 31, 2010, 05:56:32 PM

Is it the butt end of the log you are having the problem with? I have had that happen if the blade is in the "flared" part of the butt and the grain is running out of the plane ofyour blade, especially if the blade is beggining to dull and your tension is a little lite.

Magicman · December 31, 2010, 08:44:34 PM

This most probably is just stress being relieved in the log as you remove boards. Watch closely as you saw. When you see either end of the cant lift up, turn the cant 180°. As TK said, you may really have to put some pressure on the cant to bow the center back down to the saw bed before you clamp it. Watch closely again. You may saw one board or a couple before you need to flip the cant again.

Thankfully, all logs don't have this stress. The old folks called this "suck butt" because it generally is worse in the butt end of the butt log. This picture shows the cant lifted up from the support when the last board was cut. This cant was flipped 180° before the next board was sawed.

backwoods sawyer · January 01, 2011, 12:59:47 AM

The single clamp design that the hydraulic Woodmizer mills use allows the stresses in the wood to move more freely then the double clamp design of the Cook's mills, which has much more aggressive clamps and dogging barbs. One thing that will increase the amount of movement that a log has on a Woodmizer mill is if the adjustable clamp stop is out of adjustment. As the clamp bends the cant to the side3/8" or so the ends will lift up a bit. A good 6'straight edge will let you know if this is out of adjustment. I like to leave the stack in place as I pattern down thru, rather then removing each board as it is cut. This allows the cant to holds its form better while it is being sawn.

Banjo picker · January 01, 2011, 04:35:41 AM

Like Backwoods said ...when you bite a normal length cant with the Cooks it aint coming up...the board you cut may do the rocking chair :D but the cant stays down...Its good to have somebody that is farmiliar with both mills give some insite...Thanks Backwoods..Tim

Magicman · January 01, 2011, 08:46:06 AM

True.

Very seldom have I seen the center of a cant raise up. It's mostly the ends because of the banana effect. In my illustration above, that cant should have been flipped earlier. I just simply didn't notice the end raise up. I probably sawed 20-25 logs on that job and that was the only one that had to be flipped.

logwalker · January 01, 2011, 02:29:08 PM

I have some 40 or 50 lb. chunks of steel that I keep under the mill. When I know that I am going to have one end or both lift I put one of these chunks on the cant and saw under it. I move the end of the cant directly over the bunk before I do it.

Joe

terrifictimbersllc · January 01, 2011, 03:03:52 PM

Once I rigged a wire from each side of the cant around the toe rollers to pull down the bottom ends of a board for resawing, I think I used a nail in each side. Could use a very light gauge chain and fashion dog hooks to make the contraption adjustable. Wouldn't expect it to be of much use for bigger cants but it works if there's some flex and a good reason to want to do it.

terrifictimbersllc · January 01, 2011, 03:06:13 PM

Once I rigged a wire from each side of the cant around the toe rollers to pull down the bottom ends of a board for resawing, I think I used a nail in each side below the intended cut. Could use a very light gauge chain and fashion dog hooks to make the contraption adjustable. Wouldn't expect it to be of much use for bigger cants but it works if there's some flex and a good reason to want to do it.

ladylake · January 01, 2011, 05:59:52 PM

Quote from: oregonsawer on December 29, 2010, 04:46:44 PM
My saw started sawing the last two one inch boards thick and thin
about two ft. from the end.
If seams to pick it up as it saw through.
I have done a complete realinement.
The ban is right on plane.

It will saw 5/4and 8/4 real well.
Can any of you guys give me a place to start?
Thank you.

I've had the same problem and for what ever reason I've found myself increasing the feed rate right at the end of a cut, when I make a effort to slow down a bit at the end the boards turn out good. I think a a high feed rate the band will do what it wants to do with a 2" cant. Leaving a bunch of boards on top will help but when sawing with a off bearer I want them gone

Chuck White · January 02, 2011, 10:52:49 AM

I can recall a few times when I'd think that I should turn the cant, and as soon as I backed the clamp off, the middle of the cant raised about an inch.

At that point, I wished I hadn't loosened the clamp, but just kept on sawing instead, but it was too late.

Trying to reclamp it was a real bear, my 200+ pounds standing on it wouldn't bring it back down so it could be reclamped.

The only fix I could see was to let the cant relax, then trim the hump off the middle, turn 180° and trim the ends and finish the sawing.

terrifictimbersllc · January 02, 2011, 12:05:49 PM

Wondering whether one could clamp the cant back down using a clamp placed under the rail.

Yes one needs a good reason to care about not losing a board. Maybe next time this happens I'll get out my Hi-Lift Extreme jack with it's auxiliary clamp jaw, and see what happens. If it comes down easy then just re-clamp it with the sawmill and proceed.

Here's a pic of the jack in its clamping mode if you're not familiar:

Chuck White · January 02, 2011, 12:59:23 PM

TT: Your clamp (jack) sounds like a very good idea! ;)

terrifictimbersllc · January 02, 2011, 02:01:50 PM

This jack has to gain a notch to hold and they're an inch or so apart. Could use shims, or just have a helper bear down while securing the mill clamp.