blade jumping off lt-40 super in syp

caveman · January 21, 2013, 06:12:36 PM

This morning I was helping an old friend (really picking his brain during his breaks as he has been a sawyer for many years). After about two SYP logs following a brief break to turn the cant or something, the band would jump off of the wheels as he engaged the clutch. He immediately switched to a new or fresh re-sharp blade, we cleaned the B-57 belts, ensured proper blade tension, added extra detergent to the water tank, cleaned the groove in the wheels. The new blade came off at least five more times in the next two logs. He thinks the blade was sticking to the B-57 belts because of pitch build up. What did we not cover except for excessive pitch on the blade?

The mill is an LT-40 super hydraulic with a diesel. It has 600 hours. The belts were not worn to the point that the band was touching the wheels but they had some hours on them. I think he is scheduling a professional woodmizer tuneup when they make their Florida rounds in a few weeks.

JMoore and I have an LT-28. We have not had bands jump off yet but we do sometimes have excessive pitch build up when sawing SYP. I have contemplated making some kind of diesel drip, felt pad applicator for such situations. Currently, I just keep a squirt bottle with diesel to squirt the blade when the pitch builds up and the Pinsol/Cascade mix won't cut it. Thank you for your opinions on the diesel and suggestions to keep the band on the wheels of the LT-40.
Caveman

millwright · January 21, 2013, 06:19:47 PM

Are these new belts or older ones? I had replaced mine with new Goodyears and could not keep the blades on, I went back to the old ones and had no more trouble.

caveman · January 21, 2013, 06:33:28 PM

The B-57 belts were not new.

drobertson · January 21, 2013, 07:22:45 PM

I have never had this happen, it sounds like the tracking some how got knocked off? I have ran belts way past the life span and still no issues. something has to be scewed somewhere,

fishpimp · January 21, 2013, 07:43:30 PM

Curious myself! I'll jus ahead and say it , my new saw scares the 6!@#%^&* outta me!
Don't really know many horror stories about them but I'm listening!

POSTON WIDEHEAD · January 21, 2013, 07:46:41 PM

He has pitch build up UNDER the belt in the groove of the wheel. It can become as hard as concrete. Sometimes you have to chisel it out with a screwdriver and hammer. Sounds like you may have missed it.
Re-check.

CCC4 · January 21, 2013, 07:52:56 PM

I'm with drobertson. I have sawed thousands of board feet syp and never thrown a blade due to pitch. Pine pitch if anything should add traction. Breaking in a LT50 Super hydraulic once, I had some belt squeal when saw was engaged, so I made a bad decision. I started my sawmill career on a "ground hog" circle mill, they were belt drivin with I think 5 inch belts. If one of them slipped or squalled we dumped the belt dressing to it...no big deal, correct procedure. Well.....I applied belt dressing to the LT 50's belt...WOW! WHAT A MISTAKE! lol No sooner than the saw would engage, the belt would violently fly off...so bad I tore the left side door up and ripped off some little guard or something. Anyway, live and learn.

The belts were ruined, nothing would clean the belt dressing off. We tried everything we could think. They would appear clean but after warming up they would secrete the dressing, and the blade would fling off again. New belts were the only remedy.

Like drobertson said, something may very well be out of true. Pr something got on the belts.

Hey I just remembered, I learned to bandsaw on a LT40, don't they have a felt secondary belt? The LT50 I ran did not, that's why I forgot about that felt looking belt. If I remember right the owner of that saw had to replace it a couple times.

edit, just read POSTOLT40's post and he has a very valid point.

CCC4 · January 21, 2013, 08:00:38 PM

Quote from: fishpimp on January 21, 2013, 07:43:30 PM
Curious myself! I'll jus ahead and say it , my new saw scares the 6!@#%^&* outta me!
Don't really know many horror stories about them but I'm listening!

! Wait till you break a blade! POW! You rarely ever get a warning.

Magicman · January 21, 2013, 08:09:27 PM

I would consider pitch/sawdust buildup on the B57 belts, especially on the drive wheel to be normal because an amount of sawdust is always trapped between the blade and the B57. Cleaning the belts of this buildup is just routine when changing blades. I have never ever had a buildup under the B57 between the B57 and the band wheels.

My opinion is that something other than pitch/sawdust is causing the blade to jump, and blade tracking would be the most likely cause. I am assuming that the blade was properly tensioned. It was not clear to me whether the blade had ever jumped prior to today.

POSTON WIDEHEAD · January 21, 2013, 08:26:07 PM

Sometimes we have the same problems but due to a lot of different variables we have a hard time pin pointing the correct solution.

My blades have NEVER jumped off unless I get pitch build up between the B57's and the wheels. The only time I get build up is in the summer when I saw Long Leaf Pine. This is a very pitchy wood with sap running out of it like honey due to high temperatures. The honey sap will indeed get in between the belts and wheels if you don't keep it cleaned out.
This happened on my very first big job. The blade kept jumping off......I called Wood-Mizer......What are you sawing?........Sappy Long Leaf........check for pitch build up under the belt in the groove of the wheel............Thank-You Mr. Orange, Have a nice day.
That was my problem.
I've never had another blade jump off.

Magicman · January 21, 2013, 09:07:08 PM

David, thanks for your pitch buildup explanation and as usual, we all tackle different situations with our various markets.

Your example is a prime reason that giving an "always" answer simply will not work in this sawing business of ours. Every log is different, our sawmills are different, we saw different species, and we are servicing different markets.

isawlogs · January 21, 2013, 09:16:16 PM

I would saye it is one of two things, as has been said, either your B57 need replacing or there is pitch built up under them. Had that happen with white pine, the mill began to vibrate bad... it was pitch built up in clumps on the drive wheel, causing the band to jump and bounce some this causing a vibration as you engaged the mill.

POSTON WIDEHEAD · January 21, 2013, 09:18:39 PM

Well said Magic.....and I hope Caveman will give us an update when the problem is found. His fix will help others.

caveman · January 21, 2013, 10:16:42 PM

Poston, Sonny, my sawyer friend used his pocket knife to pry out sap from the drive side wheel and we rotated the belts and cleaned them. Then, a new blade was installed and jumped off 4 or 5 more times. One thing that I did notice is that he moved the blade through the log/cant much slower than I do when sawing with our lt-28 and our 10° blades. He was using 7° wm re-sharps (his preference for all around sawing). Most of the boards he sawed today were really good.

I will not have time to talk to him for the next 2-3 weeks (my next day off may be the middle of next month) but he is supposed to have the Woodmizer guy tune it up soon. This guy saws daily and has been for about 13 years. I have tried to get him on the forum as he has a wealth of knowledge but he does not mess with computers. This saw that he is running belongs to another fellow. Sonny has a 2000 lt 40 with a gas engine. Most of the stack of logs looked to be 12"-14" longleaf that has been stacked long enough that the bark would slough off with a shovel and did not ooze sap like they do when fresh cut in the warmer months. When I see him again, I will get him to tell me what the fix was.

I came home and read the WM manual for our lt-28 and did not find any obvious culprits but the lt-40 super is a different animal. He was kidding me today and said we harvested our lt-28 before it had a chance to grow up and that it was just a baby. The lt-40 hydraulics are definitely cool. If we start sawing more than occasionally we may have to look into the Pineywoods modification.
Thank you for your replies. Caveman

POSTON WIDEHEAD · January 21, 2013, 10:21:55 PM

I hope he gets it fixed. Things like this drive me crazy and makes me say_what

If Sonny has that much experience, he'll figure it out.

Tell him again we'd love for him to come on board the Forum.

Thanks Caveman.

pineywoods · January 21, 2013, 10:29:53 PM

When mine (lt40) took a fit of jumping the blade off the bandwheels, it turned out to be the bearings in the driven bandwheel. Likely a bad bearing in the idler wheel would do the same thing. Sloppy bearing lets the alignment move under load.

POSTON WIDEHEAD · January 21, 2013, 10:30:41 PM

Quote from: pineywoods on January 21, 2013, 10:29:53 PM
When mine (lt40) took a fit of jumping the blade off the bandwheels, it turned out to be the bearings in the driven bandwheel. Likely a bad bearing in the idler wheel would do the same thing. Sloppy bearing lets the alignment move under load.

How many hours was on it?

Chuck White · January 21, 2013, 11:07:36 PM

Lucky me, I've never had a blade jump off the wheels unless it snagged while backing up! :embarassed:

I don't back up with the blade engaged anymore! :P

pineywoods · January 21, 2013, 11:08:51 PM

Quote from: POSTONLT40HD on January 21, 2013, 10:30:41 PM
Quote from: pineywoods on January 21, 2013, 10:29:53 PM
When mine (lt40) took a fit of jumping the blade off the bandwheels, it turned out to be the bearings in the driven bandwheel. Likely a bad bearing in the idler wheel would do the same thing. Sloppy bearing lets the alignment move under load.

How many hours was on it?

Hours don't have a whole lot to do with bearing failure. Drive side will go bad real quick if you let the oil level get too low. Guess how I know...The idler side has 2 sealed ball bearings. If you make a habit of leaving the band tensioned overnite, it doesn't do them any good. Usually, one side goes out, allowing the wheel to pull sideways under load. If not corrected, one side of the wheel wallers out, ruining the wheel. If the blade tracking changes with tension changes, most likely one of the bearings has already gone bad ..

Nomad · January 22, 2013, 05:20:47 AM

I had the same issue with bands jumping on my LT50. The hours on the mill were very low, but it had sat neglected for some time before I bought it. After about 30 or 40 hours of using it, this problem began. It turned out the bearings on the idle side wheel were bad.

ladylake · January 22, 2013, 06:43:16 AM

If the belts are good it almost has to be the bearings. When I use diesel for lube with worn belts the band will come off when engaging the clutch. Steve

caveman · January 30, 2013, 10:26:27 PM

I had an opportunity to talk to sawyer Sonny today on the phone about something unrelated to the saw he operates but I did take the time to ask him a few questions about the mill and share some of the suggestions made on the forum as to why his bands were jumping off. He said that he increased the lubricant/soap that he uses to 2 1/2 cups per water tank and let it flow at a good rate and no more blades have come off since the day of my first post about the problem. He uses liquid laundry detergent. He expects the Wood-Mizer guy sometime next month as he is having a few other issues as well.
Caveman

barbender · February 01, 2013, 08:07:14 AM

I would actually suspect the laundry detergent, if your lube gets too slippery your blade will not have enough traction to stay on the crown. I used to have a shop built mill with rubber tires for band wheels, they are much more sensitive to this. I used diesel to cut pitch, I would just splash a bit on. If I overdid it, BAM! the blade would jump right off. I'd try sawing for a while with just eater to see if that eliminates the problem (I know you need to cut the pitch, too).