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small end first?

Started by snowman, January 24, 2007, 09:20:06 AM

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snowman

I've noticed a small problem in my lumber. Sometimes the beginning of a board is thinner than the rest of it. It's like the blade dives then levels out.It has suddenly occured to me that this seems to happen when i start my cut at the butt.Im thinking the flare causes the dive.Is this my imagination or should you cut from the small end. Alot more to this dang milling than meets the eye!

WH_Conley

Just an observation I have noticed, with small logs the tension is released as you cut. If you take sap wood from one side the sap wood on the other side will pull the cant the other way. An example of this to put a log on a band mill and cut a couple flitches from one side, turn it completely over and look at the gap between the flat and the bed rails on the mill. Make a couple of cuts and look again, cant will be flat but you will have a thin end on the last flitches you took off. Course this is only relating to stress in the log, says nothing about cutting technique (ie) speed entering the cut, blade tension, mill alignment or any of the other little gremlins that have to be about perfect. The more milling you do the more you learn to compensate for different things. Hope this is at as clear as mud.
Bill

WDH

I don't think that with a well adjusted mill that it matters which end of the log you start from.

By the way, what is a "gypo" logger (from your profile)?  Gypo seems to be a western term that I have heard several times.  I have heard the term "gypo trucker" as well.
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

Tom

Snowman,
I favor cutting from the small end on most logs.  Some people like to cut the butt end of large logs first so that they don't have to walk to the other end of the mill to take it off.

The wood in the very butt of a log appears to be harder to saw than that on up the tree.  Perhaps it is because of flair around the roots.

Your guides losing control may cause you to dive or rise and then straighten.  More down pressure may help.

Guide rollers or thrust bearings being too far back from the back of the blade will cause control problems entering the cut.

Lack of tension can cause a band to raise or dive in the cut, but it is a failure that occurs all through the cut.

Damage to the tips of the teeth on one side will cause the blade to dip or rise to the side with the least damage.

A blade being off-set will not run true.  Both sides must be pretty much equally set.  Sometimes the blade hits something on the mill that takes the set out of one side.


IL Bull

I had this happen and found that the plow for the blade was off.  That is the angle that the blade enters the log.  After the blade is in the log it will stabilize.   :P
Case Skid Steer,  Ford Backhoe,  Allis WD45 and Burg Manual Sawmill

Bibbyman

I like to saw the small end first - especially on butt cuts. 

But if you think you've got some kind of problem with the blade dive - also check the main belt tension.  It's a real gremlin of a problem that's you don't know is happening because the engine won't bog down in heavy cut.  That's the first clue.  If you think the engine should be under load and it's not..  then check the main belt tension.
Wood-Mizer LT40HDE25 Super 25hp 3ph with Command Control and Accuset.
Sawing since '94

Minnesota_boy

The blade on a band saw likes to follow the grain if it can.  When you enter the butt of a log, the blade would like to follow that curved grain, and it can since the back of the band is not supported by the log yet.  Once it is into the cut an inch, it has the support but is now cutting in a  direction that is not parallel to the bed and it takes a few inches for it to straighten out.  When the wood is frozen, the problem is magnified as frozen wood cuts harder and the colder it is, the harder it is to cut.

A real sharp blade helps but the best is to slow down the feed to a crawl for the first inch of cut and then gradually increase it to the maximum you want.  It's better to saw from the top as the grain is not curved there as it is in the butt flare, but I find it difficult to rotate a big log on the mill so I just saw them as they come.
I eat a high-fiber diet.  Lots of sawdust!

snowman

Thanks to all for the help.I never realized this milling thing would be so complex, Im sorry I ever bought one :D. Actually This problem seems to have started when my logs froze so that may be the main culprut here.Oh,and working "gypo"means being paid by the log not by the hour.You can make really good money like that and you can also go broke."Just tough this strip out, you will make it up on the next strip, gotta take the bad with the good,Iknow your going broke on this unit but the next  one you will get rich" Uh huh,right. :)

Minnesota_boy

Lots of jobs look easy as you watch someone with lots of experience but aren't that way at all when you start doing them.  :D
I eat a high-fiber diet.  Lots of sawdust!

kderby

This discussion has been a big help for me.  Thanks!  I had noticed a performance difference.  I had not seen it consistently.  Thus I do not make the extra effort to always load the small end forward.  Top down cutting is a growing preferance.  i wonder if at the big mills if this matters. It seems the big mills are so over built (a twelve inch band saw blade and how many horse power?), I wonmder if they notice a difference.

Tom

Yes, because the sawyer reads the log based on the small end.  A computerized mill reads the log from the small end.  They both make decisions on what they see from the sides.  Little info is obtained from the butt, though I'm sure both may make an effort.

wwsjr

Small end loaded toward me helps if I use the towboards. It seems my line of sight of much better to level the log if a lot of taper. Also helps to get the heavy slab off because I pull slabs from the far end of mill.
Retired US Army, Full Time Sawyer since 2001. 2013 LT40HD Super with 25HP 3 Phase, Command Control with Accuset2. ED26 WM Edger, Ford 3930 w/FEL, Prentice Log Loader. Stihl 311, 170 & Logrite Canthooks. WM Million BF Club Member.

treebucker

My brother and I have been argueing this small end/big end back and forth for some time. As mentioned earlier, the sawing judgements are base on the small end. But, on our mill it's hard to judge if the rollers or head posts are going to clear the flare looking that far down the log. By this I'm referring to logs that are maxing the capacity of the mill so bad that you can't make a test run down the track because the blade won't clear. So you have to have it right on the 1st pass.

So on the big ones we try to put the flare at the near end. The rest we generally let happen however they come out of the pile because, as someone else mentioned, it's too hard to swap ends with them. If we are lucky, the customer has piled them right or has some good equipment handy.
Last night I lay in bed looking up at the stars in the sky and
I thought to myself, "Where the heck is the ceiling?!" - Anon

Minnesota_boy

Quote from: Tom on January 25, 2007, 01:38:15 PM
Yes, because the sawyer reads the log based on the small end.  A computerized mill reads the log from the small end.  They both make decisions on what they see from the sides.  Little info is obtained from the butt, though I'm sure both may make an effort.

When I saw from the butt end, I can see the rotten hole that doesn't extend to the top end and make a judgment on how to maximize the use of this log or whether to just roll it off the mill untouched.  Since I don't do the logging, I won't know about this defect if I only look at the top end. 
I eat a high-fiber diet.  Lots of sawdust!

extrapolate85

We have struggled with the same issue in a commercial twin band stud-mill. Everything is aligned and set up per the saw-filers specification and yet we get "snipe". The best theory I have heard is that regardless of blade tension, there is an initial point where the saw flexes when starting the cut, "bull-nosing", and then straightens out as the saw enters the log (thus supporting the blade). We do know that this problem is correlated to feed speed (if the feed-rate is slowed when starting the cut, the problem goes away (we pump 800-900 stud blocks an hour through it). It also increases with frozen wood. In addition, this mill has fixed guides which means there is a generally a lot of unguided saw on anything but the largest log. I see wide face snipe a lot in head-rig logs and I speculate that it is the same. Never have noted a correlation between big end or small end, although butt-cuts in most species have a lot more water in them, and thus when frozen could aggravate bull-nosing. I don't know if your problem is anything like this, but if so, try easing into the log, then pick up speed.

By the way, what is the going rate, "on truck" for bull pine in your neck of the woods?

Dave Shepard

Bibbyman I think you may have shed some light on my wandering problem. I have been having trouble starting the cut on some hardwoods lately.  I have noticed that when I am taking a slab cut and am pushing the saw through the cut a little to fast that it will slip the belt before it really bogs the motor. I haven't noticed a lot of bogging so I just assumed everythig was OK. I'll have to check it tomorrow. :)


Dave
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Haytrader

When  I bought my mill (Boardwalk) , the fact that the blade sits at a 15% angle to the log was a major selling point to me. Only a few teeth enter the log at first. Just like sawing a board with a hand saw. We sure don't lay the handsaw flat on the board to start the cut.
Haytrader

snowman

Thanks again for even more info and opinions. The longer I use my mill the more i realize there is to know.Yesterday I sawed small end 1st all day long and it seems to be working for me.Not only less thin boards at beginning of cut but im getting more wood per log,making fewer mistakes reading my log.Tried a new thing yesterday too. I have no toe board so im using a cheap wal mart floor jack on my swell butt doug fir.It's working great.One thing though, most of my doug fir is very swept and the 1st log has so much stress in it every boards wavy.I'm thinking these logs may make better firewood. :-\ As for price of pine on the truck. I havn't a clue. I'mjust cutting my own wood for my own use these days, low production, low stress,low pay :)

woodmills1

On wider cuts, mostly in hardwood I long ago noticed a slight blade rise just after the entrance of the blade into the log.  What I did then, and now do almost subconiously, is hold back the head slightly as it enters the log.  This eliminated the little hump I was getting at the beginning of the cut, and is much easier to do than slowing down the feed rate then turning it back up.
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

C L FARMS

i like to always cut from the big end because of what post #12 said, i never find myself backing out of the cut and going to get the chainsaw to do some trimming. i can see it before i start my cut, i also find that if i mis-judge the size of the slab it is in favor of not a big enough slab in lue of to big.  the blade deflection problem is from entering the cut to fast, enter slower, let the blade speed adjust from no load to load,and allot of that problem will go away. the blade is following the sharper edge, or better spoken, it is following the edge that has more or better/sharper set.  it probably don't happen on new blades, but on slightly used blades where it is not dull enough to genuinely slow you down, but one side is dulling a little more than the other.  when i had a power feed mill where i just hit a button and it took off is where it really was a problem, with no resistence on the forward travel, it moves faster, and the sudden rpm drop when it comes under load is the culprit. on my manual feed mill the problem almost goes away, because my arm muscles judge the feed pressure, and back off before it becomes an issue.

Warren

Small and medium logs from the small end.  Really big logs from the big end so I can judge and adjust blade guide clearance BEFORE everything gets stuck at the far end of the mill...

Warren
LT40SHD42, Case 1845C,  Baker Edger ...  And still not near enough time in the day ...

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