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Hourglass cuts on sawmill

Started by JHand080, July 22, 2022, 10:31:19 PM

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JHand080

Hey guys,
I am having a major issue with milling lately. Just to get this out of the way, I have a Norwood HD-36 V2. Bunks are straight and level as well as main track. Blade is sharp, and all adjustments are as perfect as I can humanly get them. 

Every single cut I make on logs now, my boards are very very warped. My sawmill has never done this before. I can cut into the log, starting slow, and by the time I am about 2' into the log, you can already see the board start to curl up and then when I get halfway through the log it changes and drops and starts curling up the other side. When I finish my cut the board literally rocks in the cant like a see saw. 

I have never been more frustrated at a piece of equipment my entire life. I have been as patient as I can, adjusted every thing I possibly know how to, and still nothing works.

So my question is this, could it be the logs? They are differing species that have been down for about 2 years. ANY HELP IS APPRECIATED.

In Jesus,
Jon

WV Sawmiller

  No answer just more questions:

What size logs? (Length and diameter)
What species of logs?
How is your support for the mill? (Any chance something is sagging as you make your cut?)
Was the mill cutting okay in the past?
If so, has anything changed recently?
Blade type/profile?

 I am not familiar with your mill so what size engine are you using?
Howard Green
WM LT35HDG25(2015) , 2011 4WD F150 Ford Lariat PU, Kawasaki 650 ATV, Stihl 440 Chainsaw, homemade logging arch (w/custom built rear log dolly), JD 750 w/4' wide Bushhog brand FEL

Dad always said "You can shear a sheep a bunch of times but you can only skin him once

thecfarm

Could be the logs.
Any way to get a fresh log on the mill?
Even a short one, 4 feet, would tell you, because you said 2 feet it started to cut bad.
I always enter the log at full speed too.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

rusticretreater

I assume we are talking about a manual sawmill.  How wide a log are we talking about here?   Have you cut this type of wood before?

I would remove the blade and spin the wheels manually, looking for problems in the bearings, tires, drive belts, etc.  Then check your guide bearings for smooth operation.  If you have to, take them off and spin them.

After reinstalling the blade, I would spin the wheels manually while watching the blade to make sure it tracks straight, true and is properly positioned on the tire.  Make sure there is no free play in the sliding guide arm.

Watch the blade as it enters the wood.  Does it immediately cut into the wood or flex in any direction?  When the blade starts to wander, is it still properly supported by the sliding guide arm?  

It could also simply be a bad blade.  


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barbender

If the board is rising up after the cut, that is tension in the log and nothing to do with the mill at all. There's mot much you can do with those.
Too many irons in the fire

barbender

Please follow up and let us know what kind of wood it is.
Too many irons in the fire

JHand080

Thank you all so much for all of the input. I'll try to answer as many as I can in this one reply.

I have milled 6-7 logs ranging from 14"-28" all with the same results. The logs have also been differing species of wood from poplar to cherry and maple. The mill has never done this before, so I'm guessing it's either something has went bad with my mill or it's just how the logs have laid out in the sun for 2 years. I have no idea though. 

Magicman

Quote from: JHand080 on July 22, 2022, 10:31:19 PMEvery single cut I make on logs now, my boards are very very warped............... I can cut into the log, starting slow, and by the time I am about 2' into the log, you can already see the board start to curl up and then when I get halfway through the log it changes and drops and starts curling up the other side. When I finish my cut the board literally rocks in the cant like a see saw.

What you are describing is not the sawmill but tension within the log being released as you saw. 
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

JHand080

Quote from: Magicman on July 23, 2022, 06:36:03 AM
Quote from: JHand080 on July 22, 2022, 10:31:19 PMEvery single cut I make on logs now, my boards are very very warped............... I can cut into the log, starting slow, and by the time I am about 2' into the log, you can already see the board start to curl up and then when I get halfway through the log it changes and drops and starts curling up the other side. When I finish my cut the board literally rocks in the cant like a see saw.

What you are describing is not the sawmill but tension within the log being released as you saw.
That gives me peace of mind. Would that happen with every log though?

Stephen1

I would expect it in poplar ( we have cottonwood/popple) cherry moves and cracks, so does rock maple. A lot heat from the sun could make those move like they are. AS BB says, any chance of finding a fresh log?
Maybe start by taking all 4 sides off the long and then keep turning after every cut.. That might release the tension as you work your way around the 4 sides. 
IDRY Vacum Kiln, LT40HDWide, BMS250 sharpener/setter 742b Bobcat, TCM forklift, Sthil 026,038, 461. 1952 TEA Fergusan Tractor

Oddman

The knowledge of tension and how to counteract it is one of the most important skills to have as a sawyer. Knowing the mill is one thing but will only get you so far, you must know how to read a log as well.
Lots of knowledge on the forum here that should get you well on your way.
It would be interesting to see some pictures of your logs and perhaps some of the thick&thin lumber?

Oddman

Depending on the logs and how your sawing them, it could happen with each one.
In general - smaller logs, less turning and thicker cuts will cause the stress/tension to be more evident.
Larger logs, turning more often, taking thinner cuts, will relieve the internal stresses more evenly. A pith that is off center is a sign of uneven internal stress and will need to be sawn correctly to account for that. Different species of trees can have more/less stress or even build it in a different way internally.

Old Greenhorn

Jon, first, welcome to the forum, Second, filling in some of your profile info will be helpful, especially where you are. This tells us, among other things what the conditions are likely to be in your area.
 Third, take and post some photos of your general set up, log pile, and this wood that is making you crazy. There are some sharp folks here and there may be some clues in those photos you have overlooked. These are technical issues that require careful and thorough examination. Details are important. 
 How long have you been milling?
 From your description it sounds like the mill is cutting flat, but the boards are curling? Is that correct? Have you put a straight edge on top of the cant after a cut to see how it looks?
 The devil is in the details with things like this. Examine the details and post some photos so we can help. Right now we are all guessing and throwing out common issues we've all had in the past.
Tom Lindtveit, Woodsman Forest Products
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OK, maybe I'm the woodcutter now.
I work with wood, There is a rumor I might be a woodworker.

ladylake

 

 If your sawing 2 x 4 you might have to leave the cant  a little oversized  and then skim cut down to 4".   Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

Magicman

Quote from: JHand080 on July 23, 2022, 07:09:55 AMWould that happen with every log though?
Proper log setup and face opening will determine how many logs will respond when you saw them.

Mark the logs with a lumber crayon and take note of any sweep that the logs may have.  Now observe what happened when you sawed.  Orient the logs differently and observe what happens.

When sawing framing lumber I normally "saw through" from either the hump or horn face.

Asking questions is good but you will ultimately have to be your own teacher.   :P
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

YellowHammer

Imagine a piece of cheese or bologna, and no matter how you cut it with a knife, all the pieces would lie on top of each other, even if the cut was a zig zag pattern.  That is how a a neutral or unstressed log or cant would behave.  So no matter how your mill is aligned or cutting, the boards of an unstressed log or cant would just lay there, even if your band is cutting like a drunk monkey.

If the piece of wood curls up like peeling a carrot, then, as the folks say, that is log stress, and is just part of sawing.  There are lots of techniques to minimize the stress, and sometimes they work, sometimes they don't, but it's not your mill, its your logs.

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

Walnut Beast


WV Sawmiller

   Cheese, bolonga? These topics always get back to food one way or another don't they? :D
Howard Green
WM LT35HDG25(2015) , 2011 4WD F150 Ford Lariat PU, Kawasaki 650 ATV, Stihl 440 Chainsaw, homemade logging arch (w/custom built rear log dolly), JD 750 w/4' wide Bushhog brand FEL

Dad always said "You can shear a sheep a bunch of times but you can only skin him once

ladylake


 No matter how good you are at setting up logs some will have stress that shows up when sawing.  Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

YellowHammer

I din't even mention the wet noodle or fish fillet analogy. :D :D 
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

OlJarhead

This really is "sawmilling 101".  

I can't tell you the times I've learned things whether asking or not!

For those who do the answering (I try to but I'm usually beat out by MM and others who know far more than me anyway lol) THANK YOU!  I was recently told by a member who is fast approaching the Million Board Foot mark that he learned a ton because I was asking.  I loved hearing that!  Many don't ask but read what others ask and for that, I thank all of those who do the answering!  

Way back in 2010 MM and the gang were here to help me get started when I bought a CSM...and they were here when I got the LT10 and when I put a trailer under it and when I got the LT40...and passed 100Mbf and are still here today.  You are all the best!  Hands down!
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doc henderson

YH, I love your dog, but can we see a video of the drunk monkey you mention, sawing on your WM sawmill?   ;) :)
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JHand080

Y'all are hilarious 😂. Thank you for all the input. It really eases my mind and helps. Gonna start trying some more fresher logs and see what happens 

SawyerTed

 

 

Is this what's happening?  It is stress in the log.

Sometimes when you see the slab moving, the cant will lift off the bed on one end or both ends or the cant will raise up in the middle.
Woodmizer LT50, WM BMS 250, WM BMT 250, Kubota MX5100, IH McCormick Farmall 140, Husqvarna 372XP, Husqvarna 455 Rancher

customsawyer

Doc I have gotten some lumber that has come in here from that monkeys cousin. He was apparently the one that taught YH's how to drink. It was stacked on stickers by some of their other kin folk that was hitting the bottle pretty good too.
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www.thecustomsawyer.com

Peter Drouin

With the logs laying for 2 years, one face getting the all the sun. I think it would dry out the sun face, making stress in the log.
A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

YellowHammer

Sometimes I'll have some boards as carrot peeled as SawyerTed's and I'll lay them out on a scrap pile, customers will see them and ask why they bowed that bad.  I just tell them that anybody can cut a straight board but it takes a "special" kind of sawmiller and years of experience to cut McDonalds arches of that quality!
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

Peter Drouin

Quote from: YellowHammer on November 20, 2022, 07:38:27 AM
Sometimes I'll have some boards as carrot peeled as SawyerTed's and I'll lay them out on a scrap pile, customers will see them and ask why they bowed that bad.  I just tell them that anybody can cut a straight board but it takes a "special" kind of sawmiller and years of experience to cut McDonalds arches of that quality!


:D :D :D :D :D :D :D
A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

Magicman

 

 Not a record setter but still in the running for a prize.  8)
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

moodnacreek

Quote from: Magicman on November 20, 2022, 07:56:10 AM


 Not a record setter but still in the running for a prize.  8)
This one photo tells  the story in softwood. The opposite will happen in hardwood often. It appears the sawyer is trying to salvage a rotten log by taking a thick slab off and that is releasing much tension, so much it breaks off before the saw can finish. The sawyer will expect this because it happens all the time.  Softwood and hardwood are different and hardwood is the stronger and more difficult.  Think of the tree as a 4" pole [the heart] standing vertical only because the wood around it is holding up straight. Saw off a slab and it leans or pulls. [then you turn it 180 and slab the other side to straighten it and so on]

Brad_bb

The OP needs to confirm if this IS what he is seeing or NOT.  I find it hard to believe 6 logs of different species would all do this.  I've had plenty of logs dry in the sun, but now seen that kind of consistent problem.
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

moodnacreek

Well if it is not tension in the wood the cant is moving. The band saw can cut a curve but that won't make the board pop up.

FactorySeconds

A good way to rule out the mill would be to check the flatness of the piece below the cut, if it's perfectly flat, it's the wood.

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