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Band saw mills and accuracy?

Started by TW, November 09, 2013, 02:33:06 PM

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TW

During the last 15 years i have spent a couple of days per year offbearing from one of two cirkular sawmills nearby and used wood coming from bort of them so I am fairly accustomed with big cirkular saw mills. One is a new Kara Master with all bells and whistles and the other one is an old mill from the 70-ies which the owner has modernized a bit and keeps in great condition despite it's age.

Last spring we had timber sawn on a band saw mill for the first time. I was surprized that the boards and slabs got such an uneven thickness. It was an elderly Woodmizer. At work I have used band sawn timber much of the summer and it has the same issues with varying thickness. The cut in wavy so to say.

Is this a problem with all band saw mills?
Would a band saw mill with bigger diametre wheels and a wider band produce more accurate dimensions?

Just curious........

Ianab

Wavy cuts can happen but it means something is wrong. Most likely a dull band, but can also be tension, guides, feed rate or other issues. If the mill is set up and "tuned" right,  it should cut straight.

Circle mills are arguably less prone to these issues, but can still cut bad boards if something is wrong.

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

uler3161

Sounds like an inexperienced operator if the cut is wavy. Probably blade is dull or out of set. Or maybe the operator is pushing it too much. Might also be an alignment issue. If it were thick on the ends of the boards, I'd be more inclined to think there's stress in the log.
1989 LT40HD, WoodMaster 718

Dan

hunz

From my experience, the only time I see wavy lumber is when I saw large diameter 20"+ pine/spruce. This can be alleviated with a very sharp band and a slow feed speed. Other than that, you shouldn't be seeing a lot of unevenness. I would guess that the old woodmizer you speak of had improper blade tension, a dull blade, or something in the head has worn. I saw a lt50 with the 51hp diesel cut some very large white pine recently, and I didn't know lumber could be cut that true. That baby absolutely hummed too!
Dream as if you'll saw forever; saw as if you'll die today.



2006 Woodmizer LT40D51RA, Husqvarna 372xp, Takeuchi TL140

Chuck White

I absolutely agree with Ian, the most probable cause for wavy cuts on the bandsawmill would be due to a dull band.

But if the mill is up to specs on the alignment, you still have operator error to factor in, band tension, feed rate are next in line!
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

TW

This was mostly spruce but also some pine. Do the hard spruce knots in otherwise rather soft wood force the band out of course?

I would say that the thickness varied all over in a rather unpredictabe way. The variation could be as much as 8 or 9 millimetres. I am talking about houndreds of boards here so a single logg with stresses in it sould not matter too much.

Ianab

The hard knots in spruce will make any problems worse. But it still means that there is a problem with the mill. Set up properly it will cut spruce just fine.

Circle mills do seem less prone to that particular issue though.

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

Nomad

     I'm no expert, and I've cut boards I was ashamed to say came off my mill.  But it comes down to the operator.  If his mill isn't tuned properly it won't cut properly.  That is his fault.  If his bands are dull, that is his fault for not changing the band.  But he has to know enough to realize something is wrong before he can fix it.  There is no substitute for experience.
Buying a hammer doesn't make you a carpenter
WoodMizer LT50HDD51-WR
Lucas DSM23-19

Magicman

After I bought my sawmill and started portable sawing, one of the main obstacles that I had to overcome was the bad name that some "sawyers" had given portable sawmills.  These dissatisfied customers are now my repeat customers.   ;D

Properly aligned sawmill and sharp blades.   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

Chuck White

I agree with Lynn (MM), Keep your mill alignment true!

I do a complete alignment on my mill every Winter!
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

pineywoods

I have cut more than one 12 inch wide 12 ft long pine board 1/16 inch thick just show a naysayer what a properly set up bandmill will do. That's on a 25 hp manual woodmizer with close to 8,000 hours on the clock. 1 1/4 .045 10 degree mizer doublehard blade. Wavy boards are mostly an operator problem...
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

barbender

I have sawn some wavy stuff, but I stop and figure out the problem. I have had problems with large softwood with big knots, it takes a well tuned mill and sharp, sharp blades with the right set. And not to mention, I have seen those same logs give circular and swing mills fits. A properly tuned mill and blade saws straight ;)
Too many irons in the fire

GDinMaine

Also must be mentioned that any mill is only as accurate as it's operator.  If set manually one must be careful to adjust the blade height accurately.  If the boards were 8-9mm different in thickness but there was not a lot of waves, I would say it was sloppy operator.  I personally tend to have trouble with knotty and weird oak.  Large pine is far more to my liking.
It's the going that counts not the distance!

WM LT-40HD-D42

backwoods sawyer

Spuce is a wood that will let you know if you have any alighment issues even with new blades and the butt log is the worst due to cross grain.

Never the less that is not an excuse for stacks of wavy wood. Operator needs to make adjustments, replace worn parts or bow out. 

If the thickness is not consistant and no waves then it is sawhead positioning (miss reading the ruler) the accuset 2 eliminates that issue. I had a customer show me stacks of wood that was sawn on a manual set mill that looked like that. He was measuring every board coming off the mill with a set of calipers and giving a thumbs up after each one for the first half hour. I have been back to saw for him many times since 8)
Backwoods Custom Milling Inc.
100% portable. . Oregons largest portable sawmill service, serving all of Oregon, from our Backwoods to yours..sawing since 1991

Brucer

I cannot compete with commercial mills on price, so I compete on quality. If I produce wavy boards, I'll be out of business.

Every time I make a cut, I run my hand over the face of the previous cut in a long sweeping motion. If I feel a wave I stop and fix the problem. Usually it's the blade getting dull. If it's not, then I go down my long list of possible causes.

The first time I sawed a wide, dry spruce I was making big waves. Nothing I did could fix the problem. Wood-Mizer suggested I try their then new 7° blades and that solved the problem.
Bruce    LT40HDG28 bandsaw
"Complex problems have simple, easy to understand wrong answers."

Peter Drouin

Yep good alignment and sharp blades  :D
A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

slider

I like to keep a 4 ft level on hand for a strait edge .If i think there is an issue with the band wandering it only takes a few seconds to find out.
al glenn

terrifictimbersllc

Quote from: Brucer on November 10, 2013, 02:12:40 AM
I cannot compete with commercial mills on price, so I compete on quality. If I produce wavy boards, I'll be out of business.

Every time I make a cut, I run my hand over the face of the previous cut in a long sweeping motion. If I feel a wave I stop and fix the problem. Usually it's the blade getting dull. If it's not, then I go down my long list of possible causes.

The first time I sawed a wide, dry spruce I was making big waves. Nothing I did could fix the problem. Wood-Mizer suggested I try their then new 7° blades and that solved the problem.
Brucer it would be great see your list of possible causes.
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

GDinMaine

Quote from: Brucer on November 10, 2013, 02:12:40 AM

Every time I make a cut, I run my hand over the face of the previous cut in a long sweeping motion. If I feel a wave I stop and fix the problem. Usually it's the blade getting dull. If it's not, then I go down my long list of possible causes.

I would love to see the causes as well.  I admit I do make some wavy cuts in knotty hardwood and wold love to hear a checklist from an experienced sawyer.
It's the going that counts not the distance!

WM LT-40HD-D42

thecfarm

I am by far no expect. But I only sawed one spruce log,it was cut for the power line. I was cutting fine before this log and fine after it. But while cutting that spruce all I made was lumber for the brush pile.  ::) It was so wavy. Than I found this forum a while later and have heard the same thing. And I found out why.Takes a special blade to saw that stuff. I don't have much spruce on my land. I just will keep away from it now. What species I do saw,hemlock and white pine,red pine,comes out fine. I have sawed a few white maple and that did good too.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

barbender

When I finish a cut, I raise the sawhead just a 1/16" and watch the space between the blade and the sawn face as I gig back. Any irregularities are easily visible and it saves me from having another step of checking with a level, etc. My .02.
Too many irons in the fire

Kansas

Years ago, when we had our manual LT30, we were having some problems. Called Woodmizer and they asked how many hours were on it. I don't remember how many there were, but the guy suggested replacing the blade tensioner spring. Said after enough hours, they get weak.

terrifictimbersllc

Quote from: barbender on November 10, 2013, 12:28:07 PM
When I finish a cut, I raise the sawhead just a 1/16" and watch the space between the blade and the sawn face as I gig back. Any irregularities are easily visible and it saves me from having another step of checking with a level, etc. My .02.
Exactly, me too, though I usually raise the head more than this.

I find it useful to carefully sight along any square edge on a board or cant,  as I'm sawing up a log.  A wave I won't notice on a board with just one flat face, clearly shows when that board is edged. 
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

TW

Thanks guys. Knowing those two sawyers in person I can imagine why the band sawn wood comes out wavy. Neither of them has that careful analyzing mindset needed to set up a machine perfectly. Just a personality thing. Each of them owns a Kara cirkular sawmill where he saws the bulk of the wood and an elderly Woodmizer for the occasional big log. Both of them produce good quality on his Kara but not on his Woodmizer.
I suppose their cirkular sawmills are more forgiving and their setup technique is barely good enough for that.

However I am not the one to go and tell them. They are bopth great guys in thir own respective ways.

backwoods sawyer

A quick check list would include checking for a bad guide bearing, a worn or out of align saw guide, quick check for that would be a close visual check along with a few taps with your finger tip on the saw under each saw guide, back side of the band and front side . If the saw vibrates on the inside or outside the saw guide is not putting even pressure across the width of the saw.
Check guide arm rollers for slop by running the guide arm in and out while watching the saw for flex. Just to be clear all this is done while the saw is not running.
Backwoods Custom Milling Inc.
100% portable. . Oregons largest portable sawmill service, serving all of Oregon, from our Backwoods to yours..sawing since 1991

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