White pine sawing issues

[slider]

I got into this years ago sawing wide syp flooring on an lt40 with a drip lube system .What I found was too much pitch build up on the bottom of the blade.When I started hearing this sound I would spray a bit of wd-40 on the underside of the blade an it stopped the problem.Piney could be right about rpm's .Perhaps that buildup caused some resistance contributing to the problem.

[Tom the Sawyer]

I hope that it reappears sometime when I am sawing my stuff here at home (which doesn't happen very often) because it would be nice to be able to take the time to track down exactly what caused it.  As it stands, I have a lot of ideas of what to check if it ever occurs again.  I suspect it was a combination of factors, the next log (different species) with the same blade, tension, etc. was fine.

[Peter Drouin]

I hope that it reappears sometime when I am sawing my stuff here at home (which doesn't happen very often) because it would be nice to be able to take the time to track down exactly what caused it.  As it stands, I have a lot of ideas of what to check if it ever occurs again.  I suspect it was a combination of factors, the next log (different species) with the same blade, tension, etc. was fine.

You can let us all know when you find out.

[manoverboard]

So then the photo posted by drobertson is caused by blade slippage? I see this pattern on occasion....

[5quarter]

Manoverboard...Maybe. I think its more likely the hook angle of the tooth may be aggressive enough to cause some blade chatter through the knots. I run 8° and see that same pattern occasionally.

[drobertson]

It is an 8 degree blade here as well, Cooks super sharp,  it is not on every board,  Pretty sure the drive belt is tensioned to specs, nice straight cuts at a good feed rate,  when the chatter happens on me, its located  around knots,  and not every knot,  I thought it was right before the knots at first, but then saw some just after the knot
I am thinking it very well could be as mentioned earlier, speed slows down through the log,  the ones after the knot mean to me I got through the knot then slowed down, and really did not need to.  Nothing scientific going on here, glad to read the other ideas out there.

[YellowHammer]

I routinely see the pattern in Peters reply #18, and pretty much only when I saw soft wood such as poplar and soft maple. I have tried unsuccessfully to diagnose the root cause many times but although I can reduce it, I can't ever pin it down.  I have seen this since the first day I sawed poplar on my mill and still see it after many B57 changes, a new drive belt, new roller guide bearings, etc. I don't have the high performance blade guides with pads, but the standard rollers.   

The only constructive info I have is that I see it in softwood, usually with a WM9 degree blade, and more so with a sharp blade and less as the blade dulls.  I see it more on fresh, dripping wet poplar, and almost never on any kind of hardwood.

I see it in new WM 9° blades, Resharps, and Mesharps.

My only theory, which could be completely bogus, is that I am getting resonance in the blade for any number of reasons, and as the blade oscillates it's digging in and sawing the resonance pattern in the soft wood. As the teeth dull, I still have resonance but the teeth aren't cutting into the wood as well anymore, so the pattern diminishes. 
I get the patterns DR sees in Reply #19 when sawing narrow poplar slow and Peter's pattern when sawing large poplar at any speed, but usually when going pretty fast. Doesn't happen all the time but I've seen it quite a bit. I have smoothed it out some by adjusting band tension, cleaning the band wheels, swapping band tires, adjusting the nylon resonance screw on the top of the band, tightening the main drive belt, and also the up-down chain. Not sure if any of these are the problem or if I am simply changing the resonant frequency of the saw.
Also, when beginning to saw poplar and other soft wood, I engage the blade and adjust the tension until I have a minimum of blade "bounce" and it is running dead smooth.  That seems to help keep it away for the most part.

YH

[drobertson]

As someone stated, it's not an issue that I believe to scrap a board, but a very interesting issue none the less, I still believe it is a feed rate issue, but one that is hard to figure when dealing with very hard knots and very soft wood before and after the hard knots.  feed rate with a thin narrow blade is hard to maintain with these conditions. YH, I too, have checked all clearance, tensions, and measures to insure reducing the blade oscillations.

[Ga Mtn Man]

I have seen that pattern before too with both my TK and WM mills and, like drobertson, only when sawing poplar.  I have also seen a similar pattern of sawdust left behind.

 

[Chuck White]

I still think it's caused by the feed motor trying to go faster than the blade can cut.

It can also be caused by the blade "drive belt" (engine to main bearing) slipping!

These two statements pretty-much mean the same thing, "going faster than you can cut"! 

[moosehunter]

Update;
No change >:( I installed a new drive belt, I think the old one was original. I can now really load the engine with speed but still get the pattern. I found one of the guide wheels was cone shaped and had a bad bearing in it. Had a new one so I installed it. I wondering if changing to 1.5 in bands would help? I am almost done with this 15000 bdft batch and need to do 30000 more this fall/ winter. Sure would like to solve this mystery before I buy the next load of white pine. Sawed some red pine for a customer this past Saturday. Not a hint of this problem in the red pine. Back to white pine this am, problem is back.

[Chuck White]

I think I would get the issues resolved before changing to a different blade width!

To change blades at this time would only add to the problem.

Just sayin'!

[moosehunter]

I don't intend to change blade width unless that is the only option. I was asking if it may help the issue. My understanding of the way a blade works is that the sawdust in the kerf helps stabilize the blade. It seems to me the blade is not staying stabilized and is vibrating. The only thing I can think of that I have not tried yet is a thorough alignment procedure. I will try that this afternoon.

[justallan1]

I'm probably way off track here, but if the 1¼" blade is "fluttering" would a 1½" do it more? I would think with the teeth sitting further away from the guides it would afford it more of a chance to.
Just early morning thinking without coffee yet. :D

Allan