Band/Blade goin south

[REGULAR GUY]

  Howdy All,    Hope somebody can help me with this. I've got a woodmizer  lt40 auto feed. Been cuttin on  2nd log of same tree. Ponderosa Pine  of about 22" diameter , owner of log says he felled it about six months ago, bucked it up and propped it off the ground. Logs are sound with no bark. On the second log I took my first cut off the top, turned the log 180 degrees at four inches into the cut the band went drastically south?!!? It turned downwards in blue smoke! Adjustments, tension, roller guides etc. seem be to be fine. Swapped out to a new band and same thing, even when I'm  cuttin REAL slow. I noticed a black substance on the band. I use PineSol with water for lubrication. Woodmizer said to check all settins etc. ....done it. I would appreciate any advise  or help. A big  thanks in advance.

Regular Guy

[Tom]

The first suspect  is metal, ceramic, or cement in the log.   Are the teeth damaged?

The second suspect is that the band is hitting something on the mill and ruining the set, probably on the inside teeth.

Take an axe or chainsaw and cut the partial piece of slab off of the log and see if there is anything in the wood.

Have you run a metal detector over the log?

Either turn the log 90 degrees and try another cut, or turn the log end for end and try another cut.  Get out of the part of the log that is causing the problem to prove that the log is doing it or not.

Black on the band could be remnants of what the band is hitting, or it could be caused by the heat generated by the friction of the band rubbing in the kerf when the band dives.

[REGULAR GUY]

Tom,
Thanks alot for the quick reply. I checked the teeth and no damage, I'll check again tomorrow but I don't think the band is hittin anything. I did  cut off the slab and saw no metal rocks etc.  The logs  are real clean. Though I did cut one log (from same tree) before this  without any problem, I  do remember (thinkin back) that  there was a coupla  times that the band "bogged down" , you could smell it "workin", I slowed it down and it worked itself out. Dunno, it's got me buffaloed. Tomorrow I'll turn the log and try that , but I'm thinkin it's something else. Ya think if excess sap was a problem it'd show up on the band?  Dunno, it went down almost a inch when it dove down, and that was in only two or three inches before I noticed it and stopped it!
Thanks again,
Regular Guy

[Chuck White]

Could possibly be something as small as an ingrown stone/pebble that caused the dive.
Once the blade hits something and dives, they usually don't straighten out.  You have to back out and start over!

You running enough lube?

[Kelvin]

Howdy,
Are these new bands?  Self sharp and set or woodmizer?  Old pine can be pretty hard, and the 2nd log would be more prone to knots, which are the tricky part of pine, you have soft wood in between knots that are really hard.  It takes a good sharp blade with the right design.  Are these blades for softwood, or general 10 degree blades?  Your bogging down in the lower log could have been when you came into knot areas.  If the bark is off the tree it could be pretty hard by now.  Green pine that is frozen is easier to saw b/c its more consistant from knots to straight wood and the band speed stays the same. 

You mentioned that the saw was adjusted right, did you start from the begining?  Proper down pressure on outfeed roller, proper gap to backup hub, proper alignment of support bearings in all planes?  Knots will really show you what is properly adjusted.  You can force your way through clean lumber, but not dry old knots.  I would make sure alignment isn't the problem then go onto blades being proper, also feed speed.  If you charge into the knots with a smaller horse power mill you will start diving and if you dont' let up, you will be stuck.  I always listen to the sound to the motor with my whimpy hp.  25hp gas engine is very small in the world of sawmills and a lot of guys have diesels and whatnot so they dont' have to trouble as much, but gas is bad on torque so you have to maintain the same bandspeed by listening to the engine.  Slow down entering knots to keep rpms up, as well as changes in width.

Width of cut is really critical as well.  If you are 12" in the wood vs 18" its very different and takes a much sharper band to maintain a good cut.  Softwoods chips expand 3x's as much as hardwood when cut from the kerf, so soft wood bands typically have more set to them, and more aggresive hook.  you can get by with a general band, but has to be sharp and aligned properly.

This is one of the hard parts of milling. problem solving on blade performance in different situations.  Lots of variables...
Good luck,
KP

[pineywoods]

I'd bet it's the blade, not enough set or sap buildup. Most new blades come with 20 thou set. On the but cut of dry pine, that is marginal. I set mine at least 25, sometimes 30 thou.The blade tends to try to follow the grain in the wood. Learned from the school of hard knocks, make sure it's not the blade before you go messin with the saw.

[ely]

 when you get thru investigating all of what tom and the rest have said... and it is all very relevant. clean the sap build up off the band with a pocket knife... then get u some diesel in a squirt can. as you saw the pine log squirt a dab or so on the blade while it cuts. it is a pain but you will be amazed how well it cuts. i get a half dozen pine logs each year that i have to saw this way. the next log may saw fine with the water and soap mix. but i just turn my water off when i use the oil spray.

[REGULAR GUY]

Thanks All Very Much,
  Far as I (inexperienced) can tell everything is fine , tho something is obviously wrong. No flat spots on the roller guides, etc.     The bands are  10 degree straight out of box from woodmizer. I'll try the diesel thanks! Kelvin , I know what ya mean by the hardness of the knots, I'm still learning and it's fun. Can't wait to get to where ya'll are at. The weather's fierce out there , soon as it lets up I'm gonna check the tension on the drive belt. I'll let ya'll know soon as I can get to it. Thanks again, Ya'll are really great. Hope to get this soon as I got orders to fill!!
   Regular Guy

[rbarshaw]

I've noticed on old pine that has been setting and it dried out, the first few inches into the log is very difficult and unpredictable. Use of oil as lube and very slow feed usually overcomes the problem. or just cut 6" off the end of the log.

[Magicman]

You said that you were cutting the second log on the tree.  That about eliminates compression stress, etc.   Since you didn't see anything in the log, chances are there was a rock or something in the bark.   A new blade should solve your diving problem.

[jcbrotz]

Where are you located? I've been having real problems with 10deg. blades this winter all I can run and keep my quality up to par is 9deg's. Not sure why but it works so, if your log is frozen maybe try a 9 and see if your problem goes away.

[REGULAR GUY]

Thanks for all the replies everybody,
   I live in the Sierra Nevada (west slope) foothills so I don't think freezin is a problem. The logs were debarked when I got them. The problem was/is the same with two bands, one brand new from the box. I checked the tension on the drive belt and it's okay. I'll get some different bands, 4 degrees - 9 degrees (gotta try experimentin some time!!), but I'll try the suggestion on cuttin off a few inches of the log. I use PineSol     in the water for lube,  what do ya'll use, what do ya mean with OIL in the lube?  I cut real slow and get the same (diving) effect and even with some knots I get a "wave", so I'm havin a tough time with this but I know that ya'll are way ahead of me and thru ya'lls help I'll get thru this. Thanks again all, and I really do appreciate your help.
    Regular Guy

[Magicman]

I use 10 oz. of Cascade dish washing liquid.  No oil or petroleum product.  But that's just my preference.  Everyone has their favorite. 

You mentioned "tension on the drive belt" ??  What about your blade tension?  You indicated that your blade guide rollers were properly aligned.  With the mill properly adjusted and correct tension on the blade, knot wave, to me, indicates a dull or rosin, etc. coated blade.  And blade diving indicates a dull blade.  Usually one that has hit something.

[John Bartley]

Thanks for all the replies everybody,
..............................I cut real slow and get the same (diving) effect and even with some knots I get a "wave", so I'm havin a tough time with this .........

I've had these same troubles with knotty Pine, and the single thing that solved it for me, after going though all the same stuff that you have was......SET...........

Out of the box the bands were at about 0.021". I tried several sets, and found that setting my bands to about 0.030 for Pine made the problem vanish.

My experience has been that a dull, properly set band will cut slow but straight (working hard...). A band which is sharp but not properly set will cut fast, but will wander all over the place.

just my $0.02

cheers

John

[taschmidretired]

 This won't solve the  mystery but it might help you eliminate concentrating on one particular characteristic.  Regardless of what is causing the blade to do what it is doing, dullness from foriegn material, low blade strain (tension) damaged blades from the box, etc., the blade on a band type saw head will always end up wanting to pull down. When a blade gets crowded it follows the path of least resistance. That path is always easier in what ever wood you are sawing than it is in liftiing the head as an excape route.  After the blade makes a downward path, very rarely  (I haven't seen it ever) will it recover. It will then draw down your power (on smaller power sources) or blow the band (larger power sources.
 The other thing I can add, is that on occasion, I have seen the third blade out of the box stop the problem. Were these pines seasoned in a fire? Are they Ponderosa or Lodge Pole ? I think it was the 9 from WM that worked best on seasoned Doug fir.
 All T A Schmid Mills came with an attached spray lube system (the nozzle is situated where it applies the atomized liquid to both sides of the blade) and we have always reccomended a mix of bar oil and diesel. The diesel was the solvent, the bar oil held it on the blade long enough to let it work.
 Even if you hand spray it on, the most important time to apply it is before the teeth enter the wood . Stay Thirst My Friend. T A

[taschmidretired]

Dang Newbees! (meaning Me!)

I see that the logs in question are 22" 6 mo old (that's not seasoned) Ponderosa and have not been in a fire.  You really should not be having much of a problem sawing those.  T A

[sigidi]

I can't add a lot from the band perspective, but on my Lucas - first thing is to change the blade.

Interesting what TA said about bands diving, the Lucas rises in a horizontal cut if the blade is 'wrong'

After a few years I can now hear the blade 'screaming' when it is 'wrong'

I'm always amazed at how much 'learning' there is on bandsaws, my hat goes off to you guys 8)

[taschmidretired]

Sigidi,
Like I said, the blade, when crowded, circle or band, will want to exit through the path of least resistance.  Your crowded blade would find the least resistance by lifting the head instead of bourghing into the log.  On your type of mill, if you said "I'm gonna lock this head down (with lock downs or enough weight) so I can keep this crowded blade from raising up." You would simply loose power and die. Before someone think's I am jamming any one particular mill, Im not.  Every blade on every mill when crowded, will have the same reaction, trying to find it's way out through the path of least resistance.  Obviously a stationary circular head would have the biggest advantage in compensating for this the longest, but it will produce thick and thin lumber when it reaches this point.
"Cousin Joe never shorted anyone that bought lumber off his old mill,  if there wasn't a full 2 inches at one end he made sure he gave you more than enough at the other end" !   T A

[coastlogger]

Good thread lots of good info. My $.02(thats Canadian of course)worth and a few questions of my own.. Chuck White how do YOU  back a band out of a cut? Ive only ever been able to do this with difficulty unless I was cutting thin and narrow. Sawdust seems to impede the process, and yes I set to .030 so lots of sawdust gets left in cut.(Does anyone else find this to be the case?)Also, TA you say youve never seen a diving band recover. In my experience they generally do recover and its called wavy lumber. Are we talking about something different here? Oh yeah my 2 cents: I had almost exactly this diving thing happen a month ago and it was in a pitchy D Fir. Straight diesel worked wonders (like Ely says) after I restarted cut.(had to remove band from mill and"hacksaw "out the cut with an old piece of blade to get the blade out and get started again)Difference I guess was that I had obvious pitch on blade,Regular Guy doesnt say he did but I still wonder if its the prob. I agree MORE SET is best.
clgr

[taschmidretired]

 No coastlogger, I understand the wave. Someone with little experience could cut wavy lumber all day without realizing it,  He (regular guy ) is saying a new blade is just diving after a few inches into the cut, not about getting through the cut and creating wavy cuts. 
Over the years when someone was trying to describe a problem like this, they always would say the blade wanted to dive, much more than it would want to rise out of the cut. It is simply because of least resistance.
The wave, if that is the problem, as you well know can usally be cured by blade strain, sharpness, set, and feed rate. He is not sawing anything tuff so it doesn't seem likely it is the blade itself. Does anyone know if its a new or used mill?

[Kelvin]

coastlogger,
I have to back out of cuts frequently when i miss judge some of my big quarter sawn butt logs with butt flair.  With a couple wedges on the other end i usually just back up with blade stopped.  If there is too much sawdust to backup very easily a broken piece of bandblade will clear it by stabbing it in behind and raking out what you can.  Only takes a few minutes at most and beats cutting the blade if you can still resharpen it.  If it his something terrible, and lodged, then cutting might be quicker.
KP

[Magicman]

I've hit junk, had the band to dive, and then had to cut the band out.  If it is just a simple "back out", I do exactly as Kelvin suggest.  A wedge and my trusty piece of sawblade.

As TA said, knot wave and a diving blade are two completely different issues, with different causes, and different remedies.

[bandmiller2]

Guy,before you change anything on your mill pull that log off and put a different one on [not same tree] put a new band on and try it.If it cuts normally then you know its the band or the log,not the mill, then put the offending log back on and try it with a known good band.Some logs are troublemakers,and will give you fits.Sometimes you hit a pocket of pitch or as stated a pebble or grit.On pine logs I always cut an inch or so off the ends, grit and stones get stuck in the pitch.Frank C.

[sigidi]

TA, didn't think you where baggin anyone or any particular mill - so no worries there mate ;)

It is very interesting to see the different 'tips' you guys use for different blade issues; diving or wavy etc.

As I said, my hat goes off to you band guys - I realised before I bought my mill (from hanging out here before buying my mill ;D) there was a lot steeper and bigger learning curve behind producing decent timber off the saw with a band mill than there is with something like a Lucas. I admit I probably push out timber quicker now as compared to back then, but as for the finish and accuracy etc. I reckon I'm spoilt with the Lucas its a bit like cheating at times ;D

[taschmidretired]

Sigidi,
I Love swing mills (mostly Petersons  :), but I love swing mills.!  I know it's hard for anyone trying to make a living with a saw, to imagine the thrill I used to get by making  successful cuts 21 inches across in hardwood with only 10 hp gas.  Slow was better than no.!  I like your dedication to keeping things accurate.