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How fast do you run your sharpener when doing band blades?

Started by Kelvin, June 22, 2006, 07:47:52 AM

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Kelvin

Howdy!
I'm still not getting my blades to run very long after sharpening them.  Maybe 200 bd ft.  I started running the sharpener at a 2 on the speed control as was suggested here by some guys.  It takes 7 mins for the blade to go around once and it needs about 3 (to 4 for metal damaged blades) revolutions to make a sharp tip, so thats at least 21 mins, is this how long you guys leave your blades on the machine for?  The motor on the sharpener is getting quite hot to the touch after doing a few while i'm in the woodshop.  Seems like a long time for each blade.  Acutually its seems as though the blades haven't improved greatly in performance since i switched to going slow on the grinder, maybe 10% better.  Any help?  I think i better try the switch in coolant on the sawmill next.  Seems like a lot of people feel that made a difference.  Oil and pine sol with water?
Thanks for any help
kelvin

Tom

Those times sound OK but 200 BF doesn't. 

It's hard to tell from a distance what might be the problem.  I don't know what your criteria is for determining that the teeth are getting dull at 200 feet.

There's several things you could look for.   The cleanliness of the clamp on the grinder is one.  take it apart and make sure that no old grindings are keeping it from closing.  If the grind wheel can push it, then the face will not be cut accurately.

Make sure that all of the tooth is being flooded when grinding.

Make sure that you have enough set.

Look for something on the mill hitting and dulling the teeth.

Check your RPM's and blade speed.  A slowing blade will act dull.  look for belt slipping etc.

You should be getting no less than 400 feet with a small engine and attaining 600 ft, even in Red Oak.




BBTom

Kelvin,

Tom has the technical aspects covered.  That is about right for the way I do it.  

When you are done, do you have much burr on the inside of the blade?  I run the last go-round very light and the burr comes off with finger pressure.    Note that I run the sharpener right by the mill when sawing at home, and time doesn't mean much.  I am dulling one while sharpening one, and as long as it is  sharp when I need it, I am happy.  
2001 LT40HDD42RA with lubemizer, debarker, laser, accuset. Retired, but building a new shop and home in Missouri.

GF

I would also check the set after running it, could be the blades are narrow enough from the several sharpenings and the guides are taking the set out.  Just a thought.

woodmills1

I run the sharpener at 6 if I am taking one pass and about 7 if I am going for 2 light passes.  Do you have the right cam for the blades you are sharpening.  When all is well I hear kaazing kaazing one for the face and the second up the back.
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

woodbowl

Quote from: Kelvin on June 22, 2006, 07:47:52 AM
  It takes 7 mins for the blade to go around once and it needs about 3 (to 4 for metal damaged blades) revolutions to make a sharp tip, so thats at least 21 mins, is this how long you guys leave your blades on the machine for? 

:o  :o  :o  :o  :o  :o

Kelvin,
    I run my sharpener wide open.  It hits a little faster than one tooth per second. I've got an older WM sharpener. I did the very same thing your talking about for several years before figuring out that I didn't need to stay up half the night just to sharpen a few blades for the next day. I usually sharpen about 6 or 7 blades per night and it takes me about 30 minutes.

I run my blades around twice, but if I've hit a nail maybe three times. I take a generous grind off the face, gullet and backstroke. It takes about 3 minutes, 4 at the most to run the course. I go by the sound of the blade rather than the sparks. The tips don't burn and the rock doesn't clog.

I also sharpen dry.

I never dress my stone except for the initial shaping when the rock is new. It continues to reshape itself and stays conformed to the profile as long as ...........

I run all my blades as a set of about 12, and mark them with a die grinder to indicate the amount of sharpenings and sets. If you slip a different blade into the mix ....... there goes your constant rock shape as well as your advance/depth setting.

Each time I put a blade on, the advance & depth are already set and only need a minor tweek and this is done while it is moving.

If I know I'm going to get into some nails the next day and need to sharpen some old blades that are not part of my set, I'll take the rock off and put on a different rock to sharpen them with. Having to reset the advance/depth is not nearly as time consuming as reprofiling the rock to fit back into the set of 12, not to mention the rock wear is much greater and the profile of one of the good blades has changed slightly. The next time that blade is sharpened, I can tell by the sound of the grind that my constant rock is being reshaped to fit the different profile of the blade ...... I use the same rock, on the same blades of 12 and keep the same amount of sharpenings and sets through out the life of the blades.

The trick is in getting started and keeping everything uniform. If every blade has a different profile, you will be unnecessarily adjusting the pawl & depth and reshaping your rock. If you had a plunge sharpener, that would be different.

It's so fast, easy and simple, I can't believe I spent 8 years doing it by the book.

I realize this is not the traditional method of sharpening and I'm probably gona get some flac for it.

I get fantastic and consistant results at the log pile. They all run the same and there are other benifits, such as not having to adjust blade guide rollers as often. Each brand of blades can run a little different. Some will run further away from the blade guide rollers and some can even scrub.

I set at .025 and don't set again untill 3 sharpening later. If I know I'll be getting into hardwood, I use the low setting at 4 and 5 sharpenings. The set is usually down to around .018-.019 by now.

I put a back stop on my manual WM setter with an adjustable spring/nut and the setting goes at a pace of about 1 tooth per second with interuptions of a wild disobediant tooth that suddenly sets at .010 or .035 or something else.

I know this all sounds a little too good to be true, but it works very well for me and I wouldn't go back.

I hope this helps.
Full time custom sawing at the customers site since 1995.  WoodMizer LT40 Super Hyd.

mike_van

Kelvin, are your logs clean? Do they get skidded or otherwise sit where grit gets splashed on them? Just a thought.
I was the smartest 16 year old I ever knew.

Bibbyman

It's been six years or more since I quit sharpening our blades.  But back when I did,  I'd find going faster was better than going slower.  I found going around twice with a light grind was better than one heavy grind.   Going slow and heavy tended to burn the blade and leave quite a burr. 

I don't think anyone mentioned cleaning and de-burring the blade.  It's hard to get the right grind if the blade is not clean.  If you set after you grind,  then you need to de-burr else you won't get the right reading on your set.

Also,  there is sharp and then there is sharp sharp.   What I mean by that is a tooth may look sharp and even feel sharp but not have that razor edge it needs to really cut well.  How I tell is to place the meaty part of my thumb gently against a couple of teeth. Just a gentle light touch – like just feeling the heir on your forarm.  If I can slide it along and the teeth don't catch the skin,  then it's not sharp sharp.   If the teeth start to grab skin like a new fish hook,  then it's sharp sharp the way I like them.

You're not changing the gullet profile or hook angle when you sharpen your blades are you?   

I once went over to help a neighbor with his blade sharpening problem.  Found that his stone was so worn out that the arm the stone was mounted on bottomed out before it could reach the bottom of the gullet.  The gullets on his blades were something like 1/16" to 1/8" deep.  The stone was barely hitting the top of the tooth.   I helped him change the stone and dressed it, etc.   We sharpened one blade about to death trying to get some gullet depth back into it.  As the machine worked,  he expounded on his knowledge of blade technology.  One comment he made was that set was just a bunch of hooey.   
Wood-Mizer LT40HDE25 Super 25hp 3ph with Command Control and Accuset.
Sawing since '94

Cedarman

Make sure the plates that hold the blade are perfectly square to the grinding stone when it comes down.  Also that the grinding wheel is centered exactly over the blade when the wheel reaches bottom.
I am in the pink when sawing cedar.

Kelvin

THanks guys.  I'll experiment.  I have a debarker and the logs i'm talking about getting 200 bd ft out of are clean ones.  Dull is when the blade starts to wander and or the mill starts slowing significantly.  I have an LT-40 w/ 25 hp gas. 
It sounds like i should try a faster rotation speed and maybe leave them on a little longer.  It seems that even after 3 trips around they sometimes don't have a good point on them.  I figured these were just ones that hit a nail. 
I have an old woodmizer sharpener that has a really small motor on it.  I see that some of the new stuff has what looks to be pretty big motors on them.  Maybe i can't take off as much metal with this thing?

I dress the stones often to clean out metal, i don't see much burning.  I do keep switching in new blades as i break them (they seem to break a lot, maybe part of problem?) and have to reset the sharpener about every time as the blades are different heights.  I'm not changing the profile too much and i try to take the most metal off the backs of the tooth like i'm suppose to.  Everything looks good when they are done, and i set before i sharpen.

200 bd ft also might be low b/c i'm often QS oak and making quite wide cuts which seems to kill the blades.  They start wandering quite quickly.  I often only cut one large log of about 200 bd ft as i cut the cant gets progressively smaller and the blade won't wander, but if i started a new large log the blade would go all over the place and ruin good lumber.  So, i pull the blade and start a new big log cutting with a sharp one.

If i cut something softer and smaller i'd probably get more bd ft out of a blade.  Thanks for all the input.  Anyone else have any ideas please let me know.  I'm trying to get the most out of this machine and my time.  Like to learn from others!
KP

woodbowl

I should add that doing it by the book is great, but it just takes forever.  :-\

Also, the stone that I use has a binder that is not quite as strong, therefore it "clears itself", meaning that it releases the grit at a faster rate, thus the potential clogging metal as well. Ironically, the life of this stone is longer than a stronger binder type. I suspect that it is due to the constant reshaping that I had done in the past or possibly the grit is harder.

It sounds like I've always ground wide open, and "dry" .......... I haven't ....... this has only been going on for the past 2 years or so. It has been so successfull that I have neglected to try other hard binder stones at the fastest speed. I may be wrong, but I suspect that I could put on one of my old hard binder stones, turn the speed wide open, grind dry and get the same results.

Something is going on here that I do not understand, but am delighted about. When sharpening, the stone DOES NOT "kiss" the face. I've always cringed when the stone faced a bit heaver than a kiss, thinking that I was prematurely grinding away the hardness, but now I make sure that all fronts are equal. Face, gullet and backstroke have the same pressures.

One thing I am sure of is that the very tip, tippy end of the point on the tooth is deformed after sawing. It is no longer square, rather it has a rounded shoulder. You can't see it without a magnifying glass unless you have very good eyes.

When I started taking more than a kiss off the face, suddenly all my initial wave problems went away. If they didn't, the process of elimination sent me to observe the set if not, it was narrowed down to an inherent instability in the blade. This seems to be more rare now than in the past.

Do you notice an inconsistancy in the grind when the blade comes around  for the 2nd time around the weld area? A lot of blade manufacturers will plunge grind, starting to the left of the weld and ending after the weld. This causes the gullet to be lower at this point. If you set the sharpener to this depth on a new blade, after it leaves the weld area, it will really start grinding heavy, causing you to reset the advance/depth because it is higher to the right of the weld. Then when it gets to the weld again it will miss the gullet and grind too heavy on the face. I start all my grinds at least 12" to the right of the weld. When the weld comes around again, there is a very big change in the grind. Since this area is lower, it will miss the gullet, but face heavier. All you can do is let the rest of the blade catch up to the lowest point. It may take a few sharpenings the equalize everything, but after that any starting point will work as long as you end at the same place.

If there is a difference in the amount of material taken off the face from tooth to tooth, there is a difference in the depth of the gullet from tooth to tooth. The gullet/face area is "HOME". It is the standard for consistancy. If it has a different shape or a different depth, the contact point where the pawl and the gullet/face area meet will settle on a different spot and regulate the advancing consistancy of the sharpening. It is the same reason that you can interchange 3/4" & 7/8" blades on the same sharpener with minor change in settings and it will still advance the same amount and not have a 1/8" difference. If particals of sawdust lodge in this area it will lie to the push pawl, giving it a false reading. The advance will suddenly be too great, missing a face all together, causing you to scramble to reset the pawl, only to run out of the lodged sawdust causing the pawl to not advance enough and suddenly take a big, big grind on top of the tooth.

If I bring home blades like this from a job and I don't want to spend time cleaning them, sometimes I let the rock do the cleaning for me by doing a very light grind first. Sometimes there may not be any sparks. This may be where "kiss the face" is usefull.

Sorry for the long read, this has been a gold mine for me and is making me money on every job now.   8)
Full time custom sawing at the customers site since 1995.  WoodMizer LT40 Super Hyd.

woodbeard

check the alignment of your debarker, as well. I finally noticed mine was not in line with the blade, and thus rather ineffective. After I adjusted it, I noticed I was getting quite a bit more life out of my blades.

Also, Tom, when you say
QuoteI don't know what your criteria is for determining that the teeth are getting dull at 200 feet.
how do you judge when it's time to change the blade? I've been puzzling over this myself, recently.

woodmills1

not to go for the obvious but kelvin are you using pine blades on oak?  I don't usually have any wander problems in oak only in pine.  Honestly I have cut oak with blades that have already cut 400 ft of pine and they were pine blades. 

I buy pine blades and use them through 2 sharpens no set then cut oak 2 times then reset for pine.

you said you are breaking blades so there may be a rub problem somewhere. 

try checking your blade tracking if the blade teeth are not sticking out past the belts it will take the set out in just a few seconds.
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

Tom

woodbeard,
I can hear the difference in engine strain as the blade slows in the cut.  The speed of advance slows and I find myself trying to "help" the blade through the cut by advancing the rheostat.

The best thing I ever did was make myself change blades  after 600 boardfeet whether it was still cutting good or not.  that will coincide with lunch most of the time.

On my LT40, I would use 2 blades and start a third when everything was working fine.

The other thing I did, and still do, is watch the sawdust from the chute.  A sharp blade will throw large "curls" of dust.  A dulling blade will blow powder.

Watch the board in softwoods and you will see that the Late wood will cut cleanly, but the early wood will have torn fibers when the blade begins to dull.

Tom

I just thought of something else to check.  Having your guide rollers adjusted too far back will cause the symptoms that you describe. 

The lip on the back of the roller should be 1/16 or no more than 1/8 from the back of the blade.

When the blade encounters pressure from being advanced in the log, the back of the blade should be supported by this lip.  It shouldn't run against the lip unless cutting.

If the roller is two far back, the blade will not get support and will  bend horizontally. 

One thing this will do is cause stress cracks in the back of the blade and the blade will break.

Another thing it will do is cause the blade to waver in the cut.   When the blade is real sharp, it overcomes the tendency to waver because it doesn't need much support.  As the blade dulls, it requires more support.  If the support isn't there, the blade will wander.

Perhaps your blades are not dull, only not supported. 

It's something to check anyway.

gmmills

   You are getting some great advice. The only thing to check on the sharpener that has not been brought up is the blade advance arm or push pawl.  The pin will wear a flat spot where it contacts the tooth. This can cause issues with inconsistent face grinds.  I don't allow mine to wear very much before I either rotate the pin in the fork rod or change it out with a new pin. This is often overlooked as a wear part that can cause sharpening problems.

     If you try to dry grind as woodbowl. Do make sure you use a softer grinding wheel as he stated. I tried it with WM wheels and had no luck. WM wheels are harder and I get better results using coolant with them.


    I'm not too sure that you problem is related to an improperly sharpened blade.  I think you should try a 4 deg blade on larger dia logs. My average log diameter is around  18". I was having the same problems with short run times,sharp life, in wider cuts using a 9 deg blade. I read a post from FiremanEd stating that he was using  4deg blades exclusively on his LT 300 with longer run times than 10 deg blades. On this suggestion I bought a box of 4 deg blades.  Run times did increase noticably. Been using them ever since on all Oak and harder species.  Use 10 deg on Cherry, Walnut and Soft Maple with good results.

      The 4 deg profile is very simular to the 9 deg with the exception of hook angle and tooth height. The gullet shape is nearly identicle. Prior to buying a 4 deg cam I sharpened them for a short time with a 9 deg cam. Just reduce the hook angle on the sharpener head and some different stone dressing. With this in mind. You may want to try a 4 deg blade and see if your sharp life increases.   
Custom sawing full-time since 2000. 
WM LT70D62 Remote with Accuset
Sawing since 1995

Dan_Shade

Woodmizer LT40HDG25 / Stihl 066 alaskan
lots of dull bands and chains

There's a fine line between turning firewood into beautiful things and beautiful things into firewood.

gmmills

Dan,

     Check out Cook's. They have grinding wheels in a wide range of grits.  Grades 46, 60, 80, and 100.  They are softer than WM's .
Custom sawing full-time since 2000. 
WM LT70D62 Remote with Accuset
Sawing since 1995

esteadle

Check one more thing.

I found that my blade life was terrible. I was only getting maybe 8 hours of spin with my blades. When my blades would fail, they would crack in the gullet, straight down toward the back of the blade.

Then, one day I used a straight piece of metal to check that the bandwheels were co-planar (in the same plane). I laid the straight edge across the bandwheels, above and below the axles, to make sure that both inside and outside edges of each bandwheel were all touching the straight edge (they weren't). When I adjusted them to be, I found my blade life double.

I believe that bandwheels that are not co-planar will cause premature wear of the blades, because the blade gullets will undergo repeated stretch / relax cycles, contributing to fatigue, and stress cracking.

Give that a try if none of the sharpening advice works out.

Eric Steadle

jpgreen

I never read the book and also run mine like woobowl... WIDE open and dry. I run about 3 passes and progressively lightly kiss the edge on the last runs.

I know my edge is sharp, I just need to work on other things like angles.  A softer stone would be nice.
-95 Wood-Mizer LT40HD 27 Hp Kawasaki water cooled engine-

ely

i have notced that i have to slow my speed down a little when my rock gets smaller, or else it seems like it it tougher to sharpen with out getting the burnmarks. if its a new rock i use it around 40 or 45 teeth a minute ,small rock as low as 30.
i also noticed if try and just run around the band once or twice it will not really be sharp. or sharp-sharp as the bibster says. several have mentioned about bringing the teeth back up to a square tooth, and the different methods of testing sharpness.
i drag my thumbnail on the teeth as they come off what i think is the final pass. if they slide on it ,iits no where cose to sharp-sharp. should catch and hold vey well and roll a curl off if you force it backwards. to check for squareness on the tooth i just roll my thunbnail from side to side while it is caught on the tip. if it lets go the tooth is not perfect yet.
sometimes it takes me 20 minutes per band to get it perfect.

but i can also tell in the lenght of run time if i try to  half- donkey the blade during the sharpening process.

Fla._Deadheader


I run about like Tom. He taught me and I modded a little after that. Usually, 2 times around without adjusting, sometimes 3. We DO saw a lot of sand, which takes the edge off fairly quick.  I try to take as little as possible, and set after 2 sharpens, usually.

  Don't know why, but Munks blades work much better than WM on our saw. Never tried Lennox or others, after starting with Suffolk and switching to Munks.
All truth passes through three stages:
   First, it is ridiculed;
   Second, it is violently opposed; and
   Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)

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