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Bouncing blade??

Started by Ben-jamin, February 05, 2017, 05:42:27 PM

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Ben-jamin

I started a saw job yesterday and noticed there was a lot of sound coming from the blade housing. It sounds a lot like what you would expect from the offspring of a flat tire and a jet engine. There is a lot of vibration and I noticed no matter how I tightened the blade it was bouncing.  I finished the job (around 1000 board feet) but I cant say It was my favorite job experience. 
Any one have any Idea of what may be causing this?
Wood-mizer Lt35

Ga Mtn Man

"If the women don't find you handsome they should at least find you handy." - Red Green


2012 LT40HDG29 with "Superized" hydraulics,  2 LogRite cant hooks, home-built log arch.

Ox

The belts on your bandwheels are likely worn out.  Or a bad bearing on one of your shafts.  Or a bent shaft.  Or a bad blade.  Something is out of balance or no longer concentric. 

I see this on my mill.  Running full throttle, no load, I'll see the top of the blade as a blur.  The noise coming from the mill is more.   I'll adjust the tension one way or another, usually a little more, and it'll smooth right out like magic.  No more rattling.  It's the harmonics causing it.  The vibrations from the engine and all spinning parts add up and make it happen.  Changing this using the tension gets rid of it.  I'm sure you could slow down the engine to a certain rpm and it'll go away too, but we always cut at full throttle so this is where you adjust to.

Edit:  After reading the other replies, I see I didn't think of sawdust buildup under the wheel belts.  So typical of me to go to the worst and hardest instead of the simplest and easiest!  Sorry about that - it's a good thing there are many smart folks around here to help! :P
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

Brucer

It might be sawdust built up on the surface of a bandwheel belt. More likely, though, it's sawdust building up under the belt. The bandwheels have balancing holes drilled into the bottom of the V-groove and once in a while sawdust gets packed into one of the holes. When that happens you'll find sawdust starting to build up at that spot. The solution is to scrape the bottom of the V-groove.

I've only had it happen a few times, mostly when I'm sawing snow-covered logs.
Bruce    LT40HDG28 bandsaw
"Complex problems have simple, easy to understand wrong answers."

Ben-jamin

I did try a new blade Mt. Man, same thing happened. I will check the V-groove, It dose seem like it is out of balance. Haven't been sawing any snow covered logs but I have been sawing a lot of sappy stuff.
Wood-mizer Lt35

terrifictimbersllc

I would revv the blade full speed, disengage the drive/clutch, then quickly step around and watch as it coasts to a stop (with the blade covers off). Looking and listening for anything.  If it's bad as you say you might be able to see what's up. Be careful and keep your hands out of there when the engine is running or things are moving.
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

paul case

Quote from: terrifictimbersllc on February 06, 2017, 08:33:01 AM
I would revv the blade full speed, disengage the drive/clutch, then quickly step around and watch as it coasts to a stop (with the blade covers off). Looking and listening for anything.  If it's bad as you say you might be able to see what's up. Be careful and keep your hands out of there when the engine is running or things are moving.

My woodmizers dont ''coast'' to a stop so that would be difficult.  I think his problem is probably either bad belts or more likely sawdust lumps under the belt on the drive side. We had them bad enough once that the band would not stay on. A few minutes with a screwdriver will fix it.

PC
life is too short to be too serious. (some idiot)
2013 LT40SHE25 and Riehl edger,  WM 94 LT40 hd E15. Cut my sawing ''teeth'' on an EZ Boardwalk
sawing oak.hickory,ERC,walnut and almost anything else that shows up.
Don't get phylosophical with me. you will loose me for sure.
pc

terrifictimbersllc

Quote from: paul case on February 06, 2017, 12:25:53 PM
Quote from: terrifictimbersllc on February 06, 2017, 08:33:01 AM
I would revv the blade full speed, disengage the drive/clutch, then quickly step around and watch as it coasts to a stop (with the blade covers off). Looking and listening for anything.  If it's bad as you say you might be able to see what's up. Be careful and keep your hands out of there when the engine is running or things are moving.

My woodmizers dont ''coast'' to a stop so that would be difficult.  I think his problem is probably either bad belts or more likely sawdust lumps under the belt on the drive side. We had them bad enough once that the band would not stay on. A few minutes with a screwdriver will fix it.

PC
Yes I guess it depends on how well the brake strap is adjusted.
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

Ben-jamin

I found the culprit, or should I say culprits. There were quite a number of nodules of sawdust on the wheel.
Thanks for all of the advise gentlemen.

 
Wood-mizer Lt35

GAB

Thanks for taking the time to post a picture of the culprit.
Gerald
W-M LT40HDD34, SLR, JD 420, JD 950w/loader and Woods backhoe, V3507 Fransguard winch, Cordwood Saw, 18' flat bed trailer, and other toys.

Ga Mtn Man

A couple of B56's will fix that problem.  ;D
"If the women don't find you handsome they should at least find you handy." - Red Green


2012 LT40HDG29 with "Superized" hydraulics,  2 LogRite cant hooks, home-built log arch.

Percy

Quote from: Ga Mtn Man on February 07, 2017, 10:27:54 AM
A couple of B56's will fix that problem.  ;D
when I had my lt40, I preferred the 56,s as well. To get them on, I would put them over my defroster holes in pickup truck dash and heat them up big time. Made the job a little easier.
GOLDEN RULE : The guy with the gold, makes the rules.

Ben-jamin

Quote from: Ga Mtn Man on February 07, 2017, 10:27:54 AM
A couple of B56's will fix that problem.  ;D

They fit tighter than what comes standard?
Wood-mizer Lt35

Ga Mtn Man

Quite tight.  Nothing gets under them... but they're kind of pain to install.  It's an acquired skill.  Do a search on B56 and you will find a number of "spirited" discussions on the subject. 
"If the women don't find you handsome they should at least find you handy." - Red Green


2012 LT40HDG29 with "Superized" hydraulics,  2 LogRite cant hooks, home-built log arch.

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