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Woodmizer Head Bounce on Large Logs

Started by BBTom, September 30, 2011, 05:30:55 PM

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BBTom

I know my LT40 super wasn't as bad when it was new, and maybe I need to take it in and get the platinum service on it, but It only has 5300 hours on it and it had one platinum service 3000 hours ago. 

Here is the problem- When opening up a log over 28-30 inches in diameter, the head will bounce real bad.  It is as if the teeth catch and pull the head to the right, then they let go and it rebounds, then repeats with each bounce getting bigger.   I have tried adjusting the bolts until they almost catch in parts of the travel.  Does anyone have an idea what I am missing? 

Note that the Mill is just fine after I get down to 24-26" height.  Could it be that there is just too much leverage when that high? 
2001 LT40HDD42RA with lubemizer, debarker, laser, accuset. Retired, but building a new shop and home in Missouri.

MotorSeven

On my little 15 I don't get a bounce, but on a full 26-8" log it pulls so hard on the cantilever mill head that the right side trailing track falls off the rail. Spacers and adjusting the bracket has helped, but it looks to me like the bracket is so high up on the arm to have much effect.
WoodMizer LT15 27' bed

Chuck White

BB
Could be that the mill is tilted a little towards the operators side.

Not quite level side-to-side, maybe try letting it tilt a little (not too much) toward the loading side!
~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!

terrifictimbersllc

Head is supposed to pull down about 1/16" under load to give parallel cut to the bed.  I could imagine that if your mill is set up not on the level but tilted where the idle side is too high up things could be off balance.  Or there is a lot of play in the mast rails/pads or both.  I would work through the complete alignment in the manual step by step not leaving anything out, esp if it hasn't been done in about 3000 hours.
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

Magicman

My first thought was leveling.  If the loader side is too high, you could actually remove the center of gravity too much and cause the head to rock back.  Without the proper weight on the cantilever it could do squirrely things.  How do I know?

You are due for an alignment whether you opt for WM or yourself to do it.
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

ladylake


Is this happening with new blades or sharpened ones?   When I was using a softer stone on my grinder the stone would wear a bit as it went around and the teeth at the end would be slightly higher than those at the beginning unless I adjusted the hieght as it went around.  Those bands were not as smooth cutting.    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

Island Sawyer

Try checking your roller bearings. When this starts happening to me, nine times out of ten
one of the bearings is on its way out.  Once you get the head down a bit the bounce goes away
because it doesnt have the torque to get the bounce started.   

BBTom

Thanks for the thoughts. I had a job today with three beech logs over 30" diameter.  It wasn't too bad since I adjusted all the bolts yesterday, but still had to stop and let the carriage stop bouncing a couple times each pass. 

Please note that it only happens when cutting over 18-20" wide with the head over 24-26" high. Trust me when I say that the head is being pulled down the full amount.  I can hang on the outside of the head and not stop the bounce.  I weigh 230 on a good day. 

Level is not an issue - seems to happen anytime I have the large logs even when set up in my sawshed. 

Blades are new or sharpened doesn't seem to make a difference.

I didn't notice any bad bearings, but you have to lift the carriage and take the weight off of them to check them properly, and I have not done that yet,  I will tomorrow.

Thanks guys!
2001 LT40HDD42RA with lubemizer, debarker, laser, accuset. Retired, but building a new shop and home in Missouri.

woodzy88

Buy a Mahoe ,set up easy in 1 hour and no problems with 5ft logs .
woodzy88

Island Sawyer

If it is a bearing, sometimes the one that is sticking gets a little
bit warmer. If you put your hands on them all, you can sometimes tell
which one is going bad.
High and wide cuts is where it will jump around on you because of all the torque.
 

ladylake

 
I'm thinking the TK ad about cantilevered bounce is true on the heavy high powered mills as there is more flex the higher you get and no bands pulls exactly the same all the time. Mine will shake a little side to side the higher I get but with a 4 post mill it doesn't matter.   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

I regularly saw full size logs of different species, several over 30" yesterday.

I have never experienced "cantilever bounce".
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

woodmills1

lt40 no bounce
lt 70 no bounce
u have problem
James Mills,Lovely wife,collect old tools,vacuuming fool,36 bdft/hr,oak paper cutter,ebonic yooper rapper nauga seller, Blue Ox? its not fast, 2 cat family, LT70,edger, 375 bd ft/hr, we like Bob,free heat,no oil 12 years,big splitter, baked stuffed lobster, still cuttin the logs dere IAM

ladylake

Quote from: Magicman on October 02, 2011, 05:49:00 PM
I regularly saw full size logs of different species, several over 30" yesterday.

I have never experienced "cantilever bounce".


Vertical lines on pics in cypress you posted were not caused by dirt, I know what sawing through dirt looks like as I've  done it enough.  I'd guess they were caused by a little bounce.  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

jcbrotz

Quote from: ladylake on October 02, 2011, 06:34:38 PM
Quote from: Magicman on October 02, 2011, 05:49:00 PM
I regularly saw full size logs of different species, several over 30" yesterday.

I have never experienced "cantilever bounce".


Vertical lines on pics in cypress you posted were not caused by dirt, I know what sawing through dirt looks like as I've  done it enough.  I'd guess they were caused by a little bounce.  Steve


UHM they maybe caused by his lubemizer. MM can tell ya for sure but I know thats the patern mine leaves.

I have had cantilever bounce and it is generaly caused but a bad bearing or misalignment, and if you haven't serviced your mill in 3000hrs then my guess would be the latter.
2004 woodmizer lt40hd 33hp kubota, Cat 262B skidsteer and way to many tractors to list. www.Brotzmanswoodworks.com and www.Brotzmanscenturyfarm.com

Magicman

Quote from: ladylake on October 02, 2011, 06:34:38 PM
Vertical lines on pics in cypress you posted were not caused by dirt, I know what sawing through dirt looks like as I' done it enough.   Steve 

Yes, sawing through the grit/gravel imbedded into those logs did very bad things to the blades.  New blades that sawed smoothly when I began were leaving marks by the time they were dulled.  I finally started using only resharpened blades, many of which had irregularities.  All of the Cypress lumber will be planed, so blade marks were irrelevant.

As I stated in the "Sinker Cypress" thread, I had the Lubemizer going full force trying to do everything possible to help the blades.  It was squirting about every 2".  Soapy water is cheap.

None of this has anything to do with chatter or sawhead bounce.
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

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