breaking blades

[def1941]

my neighbor has a timberking hydraulic mill,have been breaking blades ,blades sometimes wont go twenty minutes,he is using the ultra blade,have very carefully checked all the setup and everthing is according to the manual,exactly,the blades have small quarte inch cracks,look like stress,all the way around the blades,cant seem to saw more than a couple of logs without breakage,we have tried different speeds and everything we can think of with not much results,after contacting the factory and using their advice we still have the same problems,could he possibly have a batch of bad blades,we tried sawing yesterday and cut back on the blade tension to 700 lbs,got through two large poplars and checked the blade and so far there are no craks showing,need some goood advice on this problem

[WH_Conley]

Can't give any advice about Timberking, someone will be along who can. Welcome to the forum. I did get a bad batch of blades one time from a reputable company and never ran the first one dull, they all broke and not in the weld either.

[Bibbyman]

Welcome to the forum!

Are the cracks on the front tooth edge or the back edge? 

Are you running steel wheels or have a v-belt pulley band wheel system?  What condition are the wheels in?

What kind of blade lube are you using?  How much?

We went through a rash of breaking new blades.  Turned out one of the guides was just loose enough it would pivot a little and thus close up the needed gap.  The bottom guide would rub the blade and cause it to overheat and thus harden and crack sooner.

[Larry]

Little over a year ago I posted my problem with breaking bands here.

https://forestryforum.com/board/index.php?topic=13940.0

Got good suggestions but the problem persisted for another two months.  Had a bearing and shaft going out on the drive side.  Replaced the shaft and bearing...like magic the cracks in the bands ceased.  When I ordered parts the factory tech told me a bearing or a shaft going bad was a leading cause of broken bands and the hardest problem to diagnose.  I'm running steel wheels...I know TK has used both steel and belts so that could make a difference.

Another problem I found was to high of tension.  We checked the gauges on 3 different machines on this thread...none gave accurate readings.

https://forestryforum.com/board/index.php?topic=10765.0

The TK was the brand with the gauge reading to low which made for to high of band tension.

The Ultra is a great band...sorta on the expensive side.  You might try the Munksfor.

[eagles nest]

my kasco mill manuel recomends 400-500 lbs
my dealer said 700- to 800 lbs
i been running 600- 700 lbs for over 2 years with no breakege unless i caused it

[Tom]

It is important to note, as Bibbyman asked, where the cracks are located.  If in the middle of the gullet, it could be out-of-line bandwheels or feeding too fast or possibly guide alignment.  If at the base of the tooth,in the gullet transition area, it is usually cutting stress like heavy feed rate, dull blade or too much rake.   If the cracks are in the back of the blade, it is a guide alignment problem.  (the guides are too far back from the back of the blade)

I wouldn't discount a bad batch of blades, but it would be the last thing I would suspect. (just because they are new, doesn't mean that they are sharp)


Usually too much tension isn't a problem if alignment is correct.  It doesn't do the blade any good, but those blades are pretty strong.  Too little tension is a different story.  The blades can slip on the wheels and overheat.  You would probably notice this though by waves in the cut, unless the blades are super sharp.

If someone has been messing around with the band-wheel alignment and gotten them out-of-plane, this would cause breaking stresses.  Check for co-planer wheels by putting a blade on and rotating them in the cutting direction.  Notice where the blade rides on the wheel.  Now turn the wheel backwards and notice where the blade rides.  If the blade moves to the front or rear on the wheels very far, you might have to go through a basic wheel alignment.  If you do this, make sure you get out your book and go specifically by your manufacturer's instructions.  Alignment is a critical thing and, to be right, must be done in specific order with great attention to detail.  "Good enough for Gov. work", isn't a phrase that works here.

[ladylake]

Are your v belts worn?  If the blade touches the edge of the wheel blades will break real fast.     Steve

[thecfarm]

Sorry I can't add anything.Lots of ideas to go with.This place is great for this.Welcome to the forum def1941.Do you have a mill?

[sawdust]

I am always awed by what I learn here. I have hardly started building and I always find something I need to plan for.

Thank you ALL.

Sawdust

[DR Buck]

Went through a rash of blade breakings in August. :(  Changed the v-belts and problem went away. 

[woodbowl]

  If the cracks are in the back of the blade, it is a guide alignment problem.  (the guides are too far back from the back of the blade)

I've always tried to keep the 1/16" gap on the power side and the 1/8" gap on the idle side just like WM recomends. However, I noticed the other day that I have a bit more travel than the gap allows.  :

There is a springiness in the blade guide arm if a little extra pressure is applied. It seems that my "V" shaped rollers may not be tight enough or the bearings are worn to the point that they tend to tilt from side pressure. In this case the back of the blade would not be supported as much as it appears.

I don't know what kind of guide arm a TK has, but it may give somewhat under side pressure as well.

[Raphael]

Hey def1941 welcome to the FF
You may have alreaady noticed that there are a few more bandsaw people here than at Logosol site.  ;)

  From what I've seen the 1100 lbs. you mentioned on the other BBS is pretty near a maximum tension for a wood cutting bandsaw but not off the charts, what width are these blades?
  Aside from what's already been said, if the 700lbs is cutting true and preserving your blades then go with it.

[flip]

Check the spring on the tension guage, it should compress, I think to 1 7/8.  It is very possible that the guage is wrong and may be reading higher than normal.  Dumb question but I have to ask, are you using some sort of lube?  I am running my TK about 1100-1300 and got about 1400bf of yellow pine before it broke and I was pushing it way hard.  make sure the guide wheels are not touching the back of the blade that will kill them early too.

[rewimmer]

I have a TimberKing B-20 and have had only one blade to break. It was because I forgot to turn the lub on while cutting some really gummy pine. Timberking furnishes a really good  DVD on setting up the mill. It really goes into detail about the proper way to adjust the wheels, guides, blade, alignment, etc. You may check to see if your  bandwheels are running true. I had a mill that the bolts were not tight on the drive bandwheel and the runout caused cracks in my blades.
Also when I was at TimberKings factory they gave us a half day class on the mill and recomended we change vbelts on the wheels about every 300 hr. I also run the recomended blade tension of 1200 lbs. with no problems. They also recomend backing blade tension off to 200 lb. after you are finished sawing or when the mill is not in use. TimberKing is also great about letting you discuss your problems with their service people.
Robert in Virginia