White pine sawing issues

[moosehunter]

I have about 15000 bf of white pine I am sawing, mostly 8x8 cants for logs for our log home walls with a lots of 2x material as a bonus. I am getting a ripple in the cut. It goes diagonally across and in the direction of the cut and is minor but bugs me that I can not figure out what is causing it. Looks like ripples in a pond when you through a small stone in. I have tried 10 deg  blades, 4 deg blades, new B-57 belts, running water/ soap lube wide open, have tried blade tension from minimum to 3000 psi. The pitch is not building up on the blades, all bearings seem smooth with no looseness. When I first started this job I was not having this problem. Something changed. Any thoughts?
mh

[drobertson]

I got a few of these at random times the last few days,  they start right at knots then the blade settles back down.  I was thinking it is related to the knots some how.  Going to check the blade clearance today.

[Magicman]

I occasionally see that pattern but I have never tried to track down what actually causes it.  It would be difficult to remember what might have happened on your previous cut where it showed up.  That plus since it is inside of the kerf, you can not see it happening.

[justallan1]

I get this around any knots or if I slow down for a knot coming. On my little mill I have to slow down for the knots and especially on anything more than 12-14" wide. I find it less with a new saw on, but it still happens.

Allan

[Sawyer697]

I use 10 Degree WM Blades and use there resharp service.

[Dave Shepard]

Probably sawing too slow. If it's the pattern I'm thinking of, it usually shows up at the beginning of the cut.

[shinnlinger]

Knots and duller bands seem to casue this for me. 

[barbender]

I get that from too slow of a feed rate.

[Wisconsintimber]

Yeah I have seen this before.  Like others have said, usually right at the beginning of a cut or cutting wide stuff(14") or wider.  Has normally been minor for me.

[Remle]

Please take my comment's with a grain of salt. Most of what I saw is white pine and spruce (spruce being worse for me than WP). Even with the de-barker I find, I need to change the blades more often as the knots seem to decrease the set on bottom of the blade more than on the top and they dull quicker as well. So suggest checking the set to see if it is equal on both sides next time it occurs. The other thing and it has been discussed in length on here is, which way are you sawing the log. I saw but logs from the stump end up and all others from the top down given the choice, that works best for me. So next time it happens, you might try turning the log end for end before making any other adjustments just for comparison.. just saying knots are a pain.

[drobertson]

I did a complete blade swap today, went with Kasco, Wood max,  all I have to say is they are worth a try. .045-7/8X 158"  real signs of a very promising productive blade.  Clearance was good, as was the alignment. so I switched for the heck of it.  Glad I did.   too slow can cause issues at times, but the same can be said about pushing through a good knot,  Once it is done, it is done, two boards with variation. 

[moosehunter]

Some more info to answer some suggestions posted. Feed rate does not matter, WM NE suggested that I needed to speed up the feed rate - pattern remained the same. This is similar to the pattern that you see at the beginning of a cut but more space between the highs and lows. Both the 7 and 10 deg blades are WM resharp. I am getting the pattern cutting wide boards or edging 2xs.
I have seen this before but it usually goes away after changing the blade. I am getting it now on almost every cut. I found pine snot/sawdust built up in the pulleys under the v-belts and cleaned it out. Still doing it.
Going on a road job to do walnut this weekend, hope it is only the white pine that I have this trouble with!

[drobertson]

I had my clearance set at .005 on the bottom guides for the .042 blades,  thought about adjusting the clearance, then put on the .045's, all cleared up. not sure if this is it or not, but a good blade is critical, just a note, the others were new and sharp.  I'm still of the opinion that blade clearance is pretty important.  It should be said, that I am speaking of true blue, straight lumber,  smooth cuts.  the pine just before this load cut straight as a string, this stuff is nice, just different.

[bandmiller2]

I really don't know, I get it once in a wile and it seems to go away after a band change. I have long suspected one or more teeth set too much and it sets up a resonance that causes the washboard. Frank C.

[drobertson]

I just remembered, the moveable blade guide could be a touch loose on one of the steel v-pulley's.  The other thing could be the blade guide on the top side, these are to keep down the oscillations of the band too.

[giant splinter]

I have only seen this pattern a couple times and agree that it is rare when it happens, is almost always at the beginning of the cut, on an angle that diagonals the common pattern that is left by the bandsaw blade. It does leave a wave pattern and shows up on the upper and lower faces in the kerf, the  mill has a slight change in the sound that the band puts out when its happening and once you get moving away from the entry point of the kerf the sound changes and returns to the more common sound that we are used to. If you are off bearing from the end of the mill you may not even see the wave pattern till you go use or trim the board as the wave pattern is in the kerf, if you use a board return you are less likely to spot this pattern on the board unless you have an off bearer that is aware of this wave pattern and looking closely at the boards he is stacking and stickering. When the blades start dulling we seem to notice more problems and start thinking "what else might be causing this?" When setting up your mill or if you need to move it to a different spot on the same job its important to set the mill up and check the deck to see that you have it set up correctly and that all the bunks are lined up straight. Things can change during the course of a day and your setup might need an adjustment or at least a check to see if for example one of the outriggers is not snug or maybe something was effected buy a log that slammed onto your deck.
I hope someone solves this problem at some point here, its the kind of thing that you may not even know happened till you go to use the board and the wave shows up out of nowhere ...... not sure it matters in some cases but it never the less is not what you wanted your lumber to look like.

[pineywoods]

Ripples (not waves) on a cut are usually the result of the blade slowing down. Most of the time because the drive belt is slipping, or the blade is slipping on the drive wheel.. Using diesel or too much soap ? Mount a bicycle speedometer on the idler wheel to see this happening.

[Peter Drouin]

 

 


Is this what you're talking about?
See the waves.

[drobertson]

Not sure if this is the pattern you are experiencing or not, but this is what I have seen on at random times.

  

 

[moosehunter]

Peter's pic is exactly what I am seeing!
I was thinking today when I moved my mill that this may have started the last time I set it up. There is a LOT of mud. So much that we had to build a board walk out of slab wood so we could move around. When I get back from this road job I will set back up in my mill shed and see if the problem is still there. Thanks for the thoughts.

[Peter Drouin]

It's the blade, something about blade harmonics. Getting a blade to do that is like winning the lottery. I have been sawing with a Wood Mizer and Wood Mizer blades for over 25 years and it has only happened 2 or 3 times. :D

[Tom the Sawyer]

It happened to me about a year ago.  Sawed about 20 logs that day, logs before and after on the same band were fine, one ash log had the ripple.  Lots of suggestions but never was able to arrive a certain factor that caused it.  It did plane out of the boards.



 
say_what

[drobertson]

I know a few hog farmers that would love that finish! maybe even in some stock trailers.

[moosehunter]

Tom the Sawyer that is what I am seeing only your example is worse! Sawed some walnut for a customer yesterday, other than 3 nails and two ruined blades they sawed out perfectly.

[drobertson]

Does this mean it was more the wood grain than anything to do with blades, guides, and the mill in general?
Just asking,

[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