bandmill blade questions

[fluidpowerpro]

I still consider myself a novice when it comes to sharpening and setting so I say this only to solicite feedback from others.
Regarding setting. What i have been doing lately is I set the teeth, trying to get each tooth "close" erroring on the high side. I then run the blade through some rollers i built to bend the tooth back a little.  The goal being that all end up the same. That way I dont have to be too concerned about what I'm setting it to because once I pull it through the rollers, they all end up the same.
I can't claim this is the best way. Only that I can make a dull blade cut good again, so as far as that goes, it seems to work for me.
I know a few others use rollers/de-setters but not sure if they use them the same way.
Looking forward to comments from others.

[customsawyer]

One other thing I'd like to point out. It is best if you're cam and push rod is indexing on the tooth to be sharpened. The teeth on these blades are stamped/pressed into the blade. I've heard it does 3 at a time, but I don't know that for sure. However, as that machine is advancing the blade you will get some slight variance from time to time. By having your sharpener indexing on any tooth, other than the one that the stone is coming down the face of, can through things out of whack by a few thousandths from time to time. Remember, the more constancy you can get out of this sharpener/setter the better your blades are going to do.   

[trimguy]

fluid, running your blade through after it is sharpened and set seems like it would mess the corner of the tooth up, ( round over, flatten ). I guess your not finding this to be so ?

[fluidpowerpro]

Thats a very good point. I can't imagine that its not doing what you describe. 
Even though my blades cut again, they are not as good as new.
I'll have to rethink my method.

[jpassardi]

My personal approach (not saying I'm an expert) is to not de-set blades. A blade should not increase in set unless there is a metal strike in which case I send it to the recycle bin.
During normal use/sharpening a blade should only decrease in set - wear, grinding & fatigue. Based on this I find I can sharpen once or twice before I need to re-set (increase only). I shoot for 0.023 and that has worked well for me.

[Stephen1]

The best advice is you need a straight edge and pointed outside corner on the tip of the tooth. If a blade is over set, I run it and keep sharpening until the set reduces or the blade breaks. 
A tooth mark on my lumber is not the end of the world. I am trying to promote the bandsaw marks versus the circle saw marks that people like. It seems like it okay for the circle saw to leave marks but not the band saw. After all it is rough sawn lumber.

[YellowHammer]

These are obviously 2 different profiles. @YellowHammer the left corner of my grinding wheel wears off before I get around the blade and gives me the rounding at the bottom of the tooth instead of a "corner " is this what you are referring to when you say don't fight the grindstone ?

Yes, if the profile of the grind changes on one band then that's a problem.  Ideally, you should be able to do several bands, several passes and not worry about it changing profile.  So if the factory profile you have seems to cause excessive wear or "hotspots" on your grinding wheel, let it find it's happy place.  I also switched to Ruby stones, they lasted longer. 

Also, the lighter the pass, the less stone wear. 

I notice the one band in your picture seems to have a much shallower gullet than the other, and the depth of the gullet is what determines how much sawdust the band can carry out of the kerf, and sawdust spillage out of the gullet during a cut is a major cause of poor cuts.  So it's important to match angle and gullet depth, when sharpening.  It's also counter intuitive, but the faster a cut, the more sawdust the band will carry out and the straighter the cut, as the gullet shape creates a vortex with the air, and suspends the sawdust like in a snow globe, and ejects it cleanly.  If the vortex can't form, and the sawdust spills out of the gullet, or the gullet isn't deep enough then sawdust will spill out into the kerf, and if that residual spillage is greater than than the set to that side of the tooth, then there is negative clearance between the body of the band and the saw kerf.  That jamming of the saddest into the body of the band  will create all kinds of cut quality problems.  I did a fairly lengthy experimental video on the subject, with a factory WM band, and you can see how sawing slow is a disaster, the sawdust spillage is horrendous, and as I sped up, the cuts got better and better as more and more sawdust stayed in the vortex and got ejected.  So a sharp band is a necessity to allow you every possible advantage to cutting faster (and flat), where an improperly sharpened and set band, or with an improper gullet, will force you to cut slower. 

I always sharpen, then set, although others do it the opposite.  I feel can get a much more accurate set off a properly formed tooth corner straight off the grinder than a slightly rounded one that hasn't been sharpened yet.  But I think that may be a personal preference, because other have good success doing it the opposite way.  Also, I generally will regrind and reshape the setting anvils to ease the angle to not impact the tooth corners so hard, and not damage them when setting.  On both my Cooks and WM setters, the grind on the anvils was not normal to the side planes of the anvils, so the amount of set would change based on where the tooth touched the anvil.  That was intolerable and would result is inaccurately set teeth.  I have long since sold my Cooks, and switched to a WM CBM.

As others have said, a properly sharpened and set band with cut better than new one, or at least as good.

As an FYI, I had a Cooks drag sharper, decent machine, for several years, it took 7 minutes per grind around, two passes per band, so 14 minutes per band, and so 4 band per hour.  I went to a WM CBN, now I can do 3 minutes per band, most times only 1 pass, so for sake of argument, overall average is 5 minutes per band to account for the messed up ones, so 20 bands per hour and all come out perfect and no fiddling with re profiling the stone.

What you are going through is normal for a drag grinder, they seem easy but there is a lot of learning curve and fiddling to get them dialed in.  That's also why it is SO Difficult to buy resharpened bands that are any good.  As Coach Saban says, "It is a process".     

[barbender]

That's a very good summary, YH. Especially the finickiness of drag grinders. People think that they can just unbox one, and sharpen blades. It don't work that way. I'd wager that at least half of people that get a drag grinder, never will learn to sharpen a blade correctly (and 50% of that number, will start to offer their services to the public😂). 

Its easier to learn to run a sawmill, than it is to learn to sharpen with a drag grinder. And probably even a CBN grinder. 

Just a general observation of mine, but when it comes to sharpening, whether it be band blades, chainsaw chains, knives, or whatever- it takes a certain "knack" for it, and I'd guess less than 20% have it. 

Back to drag grinders- I've seen some that are physically not able to make an accurate grind. Total wastes of time. Flexible mounts, bad clamps, underpowered motors. 

I have a Cooks, it is among the better drag grinders and will do a good job. It is built like a tank, kinda looks like it was built by a caveman. There are many on the market that I question if an experienced grinder operator could get passable results out of them. They're just too light, and underpowered.

[Stephen1]

I went thru the aggravation of a drag sharpener for 7 years. I would get so p!@#$ that I would just buy more blades. At one time I had over 100 blades , I was one of those % that could not really master the drag sharpener, I didn't have the patience. The grinding wheel would maybe sharpen 30 blades before it was time for another wheel, then reshape it....  The single tooth setter was something else, I used to get Cathy to do that and she did a Wonderfull job. when I finally switched to the CBN grinding wheel my life changed. I bought the BMS sharpener and dual tooth setter and never looked back. it is the best money I spent in this hobby/business 

[SawyerTed]

Lay people aka customers and beginners in sawmilling want to know how to get blades sharpened.  

Often a customer will ask if I sharpen my own blades.   Then if the blade strikes metal I often get, "You can resharpen that, right?"  

Well no.  I don't even try any more.

Here's why. 



This blade hit a 16d nail in an oak log.  My customer wanted to protest the blade charge, I went over this blade with him.  He changed his tune.  

[jpassardi]

Uh huh - scrap metal...

[barbender]

I don't do much custom on-site sawing. But even if you could resurrect that blade (which usually isn't worth the effort) you lost the potential that the balde could've sawn, plus you have to stop and swap blades. Not to mention  getting to dig it out of the log sometimes. So I wouldn't be budging on the blade charge. 

[Magicman]

 A nail/metal strike cost the customer $45 and goes in the scrap bin.  I do not and will not send any nail/metal strike blade to resharp.  Sure, maybe it could have cleaned up, but suppose it does not?  Nope....trash.

Rough sawn or not, I do not want blade marks on my lumber.

[trimguy]

Thank you guys, I have a cook's sharpener. Yes I'm definitely in the percentage that hasn't mastered it . I got aggravated with it and haven't touched it quite some time. I guess I need to devote some time to it and see if I can work some things out. I would like to have a WM cnb , but it's not in the card's right now.

Edit- one blade is WM turbo 7 , the other with a shallow gullet is a cooks 8* from when I had my first mill, same length.

[Bradm]

overall average is 5 minutes per band to account for the messed up ones, so 20 bands per hour

Where are you finding these 100 minute hours, I've never been able to find more than 60 minutes to an hour?

I think my best day sharpening bands I ran through about 85 bands with 2 different lengths and 3 different profiles (shallow gullet 7/8 Simonds, 7/8 Lenox, 3/4 Lenox ground with the 7/8 Simonds cam and a wheel profiled for the 7/8 Lenox).  I used maybe 1/4 to 1/3 of a wheel total and I run my wheels down to almost nothing.  One thing that I learned from a shop that does wide bands is to run a coarse desmond dresser (otherwise known as a star dresser) between bands to keep a sharp corner, clean the bond, and maintain my wheel's profile.  This is with a Cooks grinder and ruby wheels.

[barbender]

The best thing a person can do if sharpening for yourself, is pick one blade profile to run imo. Trying to match different profiles is hard enough when you have the hang of it. 

I run the Woodmizer Turbo 7/39. Thats what my machine stays set up for. I've had a few poeple I've sharpened blades for, I don't try to match their usually 10° standard profile blades. They get ground to a 7° face, I just do a round getting the faces. Then I readjust and make a second round to grind the back of the tooth, not worrying about the gullet. People can't find anywhere to get blades sharpened around here, so while I realize this method isn't perfect they are all happy with the results🤷

[YellowHammer]

overall average is 5 minutes per band to account for the messed up ones, so 20 bands per hour

Where are you finding these 100 minute hours, I've never been able to find more than 60 minutes to an hour?

I calculated using metric hours, using centi-minutes.     

It's common in Alabama.  

[TreefarmerNN]

Thats a very good point. I can't imagine that its not doing what you describe.
Even though my blades cut again, they are not as good as new.
I'll have to rethink my method.

If the blade traveled backwards through the desetter, I would think it would have very little effect on the tooth edges or points.

[YellowHammer]

New bands will have individually overset teeth from the mass production process, that's why there are sometimes streaks on boards from new bands.  However, as a band gets sharpened and set, each time the randomness and standard deviation on the set should decreases as the teeth get ground to exactly the same height, the gullet gets ground to exactly the same shape and depth, the teeth are set exactly the same distance, the springback is exactly the same, and the indexing is exactly the same.

Basically, each time a band gets ground and set, the geometry of each tooth should get more and more precise, accurate and duplicative of all the other teeth, and so the quality of the board finish goes up and the tooth corners get honed.

I've had people look at my rough sawn boards and mistakenly think they have been through a planer. 

Also, I hate sharpening and setting bands, and I also hate that I have farmed it out to several (many) different sharpening companies, some who have all manner of high dollar computerized sharpening equipment, and I hate that I get garbage back from them, and I hate that I have to do my own.  The only part I Like about sharpening is that when done properly, it will make a band run better and smoother than new.   

[jpassardi]

For those using drag sharpeners you may want to consider trying Woodland Mills "Pro" CBN wheel. I have their Pro model 2 speed sharpener which believe it or not - is made in Sweden, not China. It uses a narrow CBN wheel without a profile so it's essentially a CBN drag sharpener. It has a 5/8 arbor as I recall. It gets the job done and produces sharp points when viewed under magnification - I will confess, sharpening & setting isn't my favorite use of time.

[fluidpowerpro]

Thats a very good point. I can't imagine that its not doing what you describe.
Even though my blades cut again, they are not as good as new.
I'll have to rethink my method.

If the blade traveled backwards through the desetter, I would think it would have very little effect on the tooth edges or points.

Actually, I do pull it through the rollers backwards.

[chainsaw_louie]

Wondering as blades are reused , can reducing the psi on the tension-er prevent breakage without affecting the cut?

  I'm discovering that with this type of sharpener, it takes a lot of attention to detail to make a blade sharp and set to within thousandths of an inch. 

I'm sort of surprised that the mfg's instruction manuals don't go into more detail about actually sharpening a blade but perhaps if they did, it would scare customers away.

 It's definitely got a learning curve and is part art and part science.

Fiddling with band tension to remove *flutter is sufficient and usually will result in less than MFG strain recommendations. I'd stick with specified tension for now.

It does take attention to detail and constant monitoring until every aspect of the procedure results in repeated sharp correct profile blades.

You are correct that it is art and science, more-so with the drag sharpener than the CBN.  Correct grind wheel profile and proper machine setting will *ultimately result in grinding the entire blade profile in a single pass though. 

Wheel profile can be thought of as another 'just as important setting'.  A change in wheel profile must be made hand in hand with machine setting.  Take too much off the wheel and the machine setting might be radical or made impossible to profile the entire surface.  Initial wheel profile should be done a little at a time combined with minute and careful machine settings.  It's rare to adjust one without a need to make accommodating adjustment of the other.

Starting at the face of the tooth *without actually grinding/honing is my first step.  Then I get the depth of the gullet setting somewhere near the bottom of the gullet.  From there you can judge where the stone needs to be shaped.  Eventually ALL the *adjustments will result in slight sparks off the entire surface.  If not.....either the blade profile doesn't match the cam or the stone...or further adjustments are needed.

My preference is for a few thou deeper gullet which requires less material removed from the *bottom left of the wheel.  This means I gotta take a tiny bit more off the angle of the wheel on the right side....and... drop the depth stop adjustment on the machine. 

The above are small examples of fine tuning that will result in complete grind in a single pass. May not be the *first pass on a blade profile or when using a new stone.  Your photos show a course grind surface and bluing.  Both indicate too much material was being removed too fast.  Slow the rate or grind/hone less.  Personally my patience is sated by grinding less and speeding up the rate.

Accurate manual setting will become second nature after hours of practice!  Well, maybe it took me longer than that. Ha.  Different blades require more or less over-set to get where they need to be.  First few teeth will tell you what you need to know afa as over-set.  Dead set accuracy isn't necessary and nearly impossible so cut yourself some slack there.  Within three thou is what I shoot for and have the dial indicator set for that range. 

I've been fussing with my Woodland mills RS8 drag grinder.  Btw this is a one speed only grinder so there is no way to slow down to reduce bluing or other issues. I really wish the mfg would have someone with many hours of trial & error experience write an in depth white paper on how to get the best results. Often it's the users and not the builders of things who really know how to get the most out of products .

I can tell based on the comments here that I'm removing too much metal but I chalk that up as the price of my education.

The thought has occurred to me that I should be able to reverse engineer a cam shape that perfectly matches my blade by manually following the edge of the grinding wheel around my WM Double Hard bands and somehow tracing out the path on the cam.

Grinding back of tooth on 2nd pass, so far I can get it in one pass on WMlls RS8. I'm definitely taking off too much steel, can't yet get a nice smooth blade profile matching glide path of the grind wheel:




Another thing... are these lines actually fractured steel in this broken band ?

[Ben Cut-wright]

"Btw this is a one speed only grinder so there is no way to slow down to reduce bluing or other issues. "

Videos of that sharpener show the "one speed" advance is comparative to a very *slow advance rate for a variable speed setting.   This means the *amount of material taken off has to be less (per each rotation) in order to reduce bluing and produce smoother stone marks. 

"I'm removing too much metal but I chalk that up as the price of my education."

 Yes, the indicators of harsh grind marks and bluing show WHAT caused them.  Removing less each pass is how to alleviate those problems and possibly contribute to proper face grinding the tooth. 

It may be preferable to learn to use the sharpener as it is designed rather than fabricate components to correct improper operation.   If you meant making a cam to fit another profile, then it might be wise to first become proficient using the same cam profile as the blade you are trying to sharpen. 

"can't yet get a nice smooth blade profile matching glide path of the grind wheel:"

Sharpening a used blade with the cam designed for that blade often requires some degree of skill and technique.  Once proper setup procedure for the blade or same blades is setup, there is only monitoring to determine how many passes to make.  The sharpener you have takes some time to make a pass.  No matter how many passes or how much time it takes,  the goal is sharp teeth and proper profile. 

The marks in the photo might be superficial scratches.  Cracks that far into the body of the band can be proven by bending or magnification.   Pays to inspect marks like that very closely. 

[barbender]

I'd say that those are gullet cracks with near 100% certainty. That is where they always form. Folks want to blame other things, but these are the two most common causes of gullet cracks- running dull blades, and just regular fatigue. 

[ladylake]

   

  Running the back of the blades to close to the guide roller flange is the biggest blade breaker when sawing hard,  You need 1/4"  between the blade and flange.  Soon as the blade hits the flange its going the crack the gullets   Steve