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Blade flexing up in cut. Help

Started by RPowers, November 13, 2015, 10:15:13 PM

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RPowers

I am running an LT-28 so there is no factory way to know what kind of tension my blade is at.... just that red rubber spring thing that you compress. I did buy a dial caliper and plan on testing the tension by measuring stretch.

After reading some articles on Cooks site I am wondering if these need to be rolled flat, as they are all on their 4-5th resharpening.

RE: resawing. This is one of the things that set me on this path of correction... I tried to resaw a large 3" white oak slab down to 2" for a customer, and every new Resharp blade I tried climbed out of the wood, even at slow speeds and way over the factory tension. My rollers were spot-on aligned too. It is frustrating and I am going to figure this out because I can't cut wavy lumber for people.
2013 Woodmizer LT28G25 (sold 2016)
2015 Woodmizer LT50HDD47

POSTON WIDEHEAD

Your screeching belt just sticks in my mind. It should not be doing that sawing slow.
I really think its the blade tension not being high enough.

Keep trying things.
The older I get I wish my body could Re-Gen.

JB Griffin

Its possible that your rubber spring is weak and ain't putting enough tension on the blade, not likely though.
2000 LT40hyd remote 33hp Kubota with 6gpm hyd unit, 150 Prentice, WM bms250, Suffolk dual tooth setter

Over 3.5million bdft sawn with a Baker Dominator.

Ox

Your screaming drive belt post is stuck in my head.  If this is happening during a slow cut, in my mind it means the blade is heating up and being pinched in the cut creating more friction.  Maybe try checking the set on the teeth of the blade with your new calipers.  With hardwood around .020 set works well for me.  I firmly believe too much set is better than not enough set.  A hot blade will do all sorts of crazy stuff because it is now "softer" and more able to move around.  Plus it has lost some tension which makes it do crazy things.  Maybe try some lube on the blade as well?  Diesel keeps things cool and slick and you don't use enough of it to hardly matter.  Others have different concoctions they like and works well for them, I'm simply saying what I use and works for me.  You could just use a spray bottle temporarily.  It might make a world of difference.
K.I.S.S. - Keep It Simple Stupid
Use it up, wear it out, make it do or do without
1989 GMC 3500 4x4 diesel dump and plow truck, 1964 Oliver 1600 Industrial with Parsons loader and backhoe, 1986 Zetor 5211, Cat's Claw sharpener, single tooth setter, homemade Linn Lumber 1900 style mill, old tools

LeeB

Ox may have a point. Blade speed could have much to do with it.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

RPowers

I tried the calipers to check deflection, and over 6" of blade I am stretching the band about 6-7 thousandths. So my tension should be plenty. I talked with Resharp, and the thought now is that the 4 degree blades I have are on their 4-6 sharpenings, so maybe we are beyond the heat treat in the tooth, and the steel is thinner or cupped or whatever allowing the band to move. The brand new blades I tried did not have this problem like the Resharps(I tried 4) did. I hate to buy new blades with almost 30 Resharp'd blades sitting there, but if these things don't straighten out I'll have to. I'm thinking of sending a handful to Cooks and having them benched or rolled to recondition the steel.
2013 Woodmizer LT28G25 (sold 2016)
2015 Woodmizer LT50HDD47

YellowHammer


It's odd that the resharps are not performing as advertised.
YellowHammerisms:

Take steps to save steps.

If it won't roll, its not a log; it's still a tree.  Sawmills cut logs, not trees.

Kiln drying wood: When the cookies are burned, they're burned, and you can't fix them.

Sawing is fun for the first couple million boards.

Be smarter than the sawdust

kelLOGg

RP,
I have experienced this "barrel" cut but never solved it. It occurs after the blade has cut for a while and maybe begins to dull a little but it occurs to soon for me to be convinced sharpness is all there is to it. A very sharp blade can cover up the need for other "adjustments" soon to show up but I have never found that smoking gun. I have also never had a band rolled and I am very curious if this would solve the problem. The FF wisdom is that only steel wheels (like mine) require rolling but Tim says all bands need it (and has told me of accounts where all he did was roll a band and it cut straight). If you have it rolled I would be very interested in the outcome. Hang in there,
Bob
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

xlogger

I was told once that if you turned the blade inside out and put it on the mill and ran it for a few minutes it would do the same as band rolling it, of course don't cut any wood while doing this.
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

kelLOGg

Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

slider

You can check the blade with a razor blade to see if it needs rolling.Use a light behind the razor blade.
al glenn

Solomon

I've been using Munkfor blades from Kenna-Saw since I first got my LM-4 over eight years ago.
They are 229 inches x 1 1/2 x 7/8 with a 10 or 12 degree pitch.
I buy 50 or more at a time for $27.00 each drop shipped to my front door.
Other than hitting a foriegn object or a very hard knot, I've had no issues with the blade rising and diving in the cut.
Theese are new blades out of the box and the ones I set and sharpen seem to work just as well and leave a very nice finish on the board.
Assuming your mill is in proper working order, perhaps you should give them a call.
Great blades a a really decent price. 
 
Time and Money,  If you have the one, you rarely have the other.

The Path to Salvation is narrow, and the path to damnnation is wide.

kelLOGg

Quote from: slider on December 02, 2015, 07:13:21 AM
You can check the blade with a razor blade to see if it needs rolling.Use a light behind the razor blade.

I've seen new blades right out of the box show the arc of light under the razor.  :-\ :P
Bob
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

terrifictimbersllc

Wouldn't a thousandth or two in band cup, if it is there, be of no consequence , in light of all the tooth set (25 thousandths on each side for example)?
DJ Hoover, Terrific Timbers LLC,  Mystic CT Woodmizer Million Board Foot Club member. 2019 LT70 Super Wide 55 Yanmar,  LogRite fetching arch, WM BMS250 sharpener/BMT250 setter.  2001 F350 7.3L PSD 6 spd manual ZF 4x4 Crew Cab Long Bed

pineywoods

A head scratcher problem. I had a similar problem, what I found may shed some light on the situation. I sharpen and set my own, so no outside influences. Sawing some syp 1X12 and got into a bunch of embedded rocks, dulled the blade a bunch, so tossed in the "to be sharpened " pile and went on sawing. Later cleaned up the blade, set and sharpened. Put it back on the mill to edge some 4/4 stuff and got the worst case of dips and dives I have ever seen. Must be the re-sharp  ::) , so set and sharpen again. Same thing, other blades saw just fine. The logical thing to do would be to toss the blade and forget about it, but that just ain't my nature.
A bit of comparison with a good straight edge shows the blade between the guide rollers to be bowed outward slightly, ie the tooth edge of the blade is just a bit longer than the back edge, likely stretched from sawing through marble sized rocks. A little pressure against the wood, and the blade will twist either up or down depending on other forces. No logical way to shrink the tooth side, but can stretch the back side to match. Rolling will do exactly that, but I don't have that capability, so..lay the blade on a flat metal surface (anvil) and hammer the back 1/4 inch or so every inch, all the way around the blade. This will stretch the back edge just a tiny bit.
In retrospect....I see numerous references on the forum to the need for rolling band blades to take out cup, especially with cooks blades and mills. I run woodmizer blades and equipment, never saw any need for it. What escaped me is that for a blade to cup, the center of the blade will be a bit longer than the edges. Exactly what you would see with crowned metal wheels and to a lesser extent with belted wheels running crowned belts. If the stretch is a bit off-centered (likely after a few sharpenings) the result is a crooked blade. Now from a practical standpoint, blades will probably break from repeated flexing before this becomes a problem, BUT mr. Murphy is well acquainted with sawmills.
1995 Wood Mizer LT 40, Liquid cooled kawasaki,homebuilt hydraulics. Homebuilt solar dry kiln.  Woodmaster 718 planner, Kubota M4700 with homemade forks and winch, stihl  028, 029, Ms390
100k bd ft club.Charter member of The Grumpy old Men

customsawyer

When you check a blade for flatness sometimes you have to check it while it is on the mill. If your blade is cupped a few thousandths of a inch it will make your blade cut that much more on one side and that much less on the other. Combined you can be looking at a difference .005-.010 from side to side and this will make your blade dive, climb or crown.  The flatter your blade is the flatter your lumber will be.
In this particular case I think the OP is possibly looking at a different issue. If his belt is squealing while he is going slow there is a good chance that the set is so far out that the blade is binding in the cut. If he wasn't going slow he would likely stall his engine.   
Two LT70s, Nyle L200 kiln, 4 head Pinheiro planer, 30" double surface Cantek planer, Lucas dedicated slabber, Slabmizer, and enough rolling stock and chainsaws to keep it all running.
www.thecustomsawyer.com

Kbeitz

So.... If your blade is cupped a few thousandths of a inch you could make up for it by setting the teeth on the other side to make up fpr it... Right ?
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

terrifictimbersllc

In quite a few yrs now of paying attention to band sharpening, I've never seen any discussion from WM about band flatness, and they don't sell a roller. 
DJ Hoover, Terrific Timbers LLC,  Mystic CT Woodmizer Million Board Foot Club member. 2019 LT70 Super Wide 55 Yanmar,  LogRite fetching arch, WM BMS250 sharpener/BMT250 setter.  2001 F350 7.3L PSD 6 spd manual ZF 4x4 Crew Cab Long Bed

SawyerBrown

OK, just a couple of thoughts, since my LT35 is running the same engine and blade tension red-rubber-compression-thingy ...

I too have cut a considerable amount of wide oak (and other hardwood) boards without this happening.  But I've never had drive belt squeal, not even close -- the engine will lug long before the belt starts to slip.  So if the engine isn't lugging but the belt is slipping, the blade may be slowing down considerably.  Have no idea whether that explains anything, but could imagine that would move a lot less sawdust for every length of travel.  Same idea as engine speed too slow as was mentioned earlier.  If it's still happening, I'd re-check belt tension.

I've never had to over-tension the blade to get it to cut straight.  Personally I don't think that's the issue, at least with our size machine.

If the blade is taking an immediate climb regardless of which blade you use (new vs ReSharp, other variables), that seems to me to indicate guides pointing the blade up-hill.  But I assume you checked all that if you went through  the whole maintenance sequence ...??

Finally, I've had some issues with ReSharp blades of late, but not as you're describing.  I'll get a scratch mark from tooth/teeth offset problem as soon as I take them out of the box (see photos), but the blades seem relatively sharp (but maybe not as sharp as new??), and still cut straight.  New blades don't do this at all.  So I wouldn't rule out other ReSharp problems.  (Note: in WM's defense, they have checked blades that I've tagged, agreed there was a problem, and not charged me for re-sharpening ... still a great company!)


  

 



Pete Brown, Saw It There LLC.  Wood-mizer LT35HDG25, Farmall 'M', 16' trailer.  Custom sawing only (at this time).  Long-time woodworker ... short-time sawyer!

Magicman

The above indicates a tooth missing or a tooth with very little set.
Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

It's Weird being the Same Age as Old People

Never allow your "need" to make money to exceed your "desire" to provide quality service.....The Magicman

customsawyer

Quote from: Kbeitz on December 02, 2015, 05:21:55 PM
So.... If your blade is cupped a few thousandths of a inch you could make up for it by setting the teeth on the other side to make up fpr it... Right ?
Wrong due to the fact that the blade isn't going to run consistently on the blade guide rollers.
Two LT70s, Nyle L200 kiln, 4 head Pinheiro planer, 30" double surface Cantek planer, Lucas dedicated slabber, Slabmizer, and enough rolling stock and chainsaws to keep it all running.
www.thecustomsawyer.com

JB Griffin

My best guess is either engine speed too low or drive belt and or drive pullys glazed over and not gripping like they ought to.
2000 LT40hyd remote 33hp Kubota with 6gpm hyd unit, 150 Prentice, WM bms250, Suffolk dual tooth setter

Over 3.5million bdft sawn with a Baker Dominator.

Jim_Rogers

I thought I read somewhere that when a blade rides up it's called "log push off."
and that most of the time that it happened it was because of a dull blade.
If this is happening with every blade put on then it must be the sawmill and not the blade(s).
Cutting slow and hearing the belt squeal means it is slipping. Belts should not slip. The belt tension is not right, if it squeals, in my opinion. If it is slipping then the blade is not traveling at the correct speed to do it job correctly. This could be the cause, or at least contribute to the cause.

I have had the blade ride up. Changing to a sharp blade has always solved that problem for me.

Blade tension is important as well. A clean blade that is not rubbing either the log or the board is important too. A rubbing blade gets hotter. A hotter blade gets longer and thereby looses tension. With dial indicators we see that when the pointer goes down.
If you don't have a dial indicator then you have to increase the blade tension if you feel the blade and it is hot/warmer then normal.
If it is rubbing the log or the board then it could be a sign of not enough set to remove the wood so it doesn't rub.

I'm sorry but I don't endorse using diesel to keep a blade clean. The mill manufacturer says use water to keep your blade clean. Build up on the blade makes it fatter and then it can rub the log or the board and get hotter. When I see my blade getting hot (my dial indicator goes down) I increase the water lube flow to keep my blade clean and cool, so it cuts straight as it can.

Jim Rogers

Hopefully you'll find the solution soon.
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Magicman

Thank you Jim for a well thought out reply.   smiley_thumbsup
Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

It's Weird being the Same Age as Old People

Never allow your "need" to make money to exceed your "desire" to provide quality service.....The Magicman

sawdusty1

Could bad bandwheel bearings with too much play cause this?
Woodmizer LT15
Husqvarna 550xp
Husqvarna 372xp
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Husqvarna 55 Rancher
Husqvarna 181se
Kubota L4701

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