My band-mill came with 10 blades , a electric band sharpener and a saw-blade tooth setter. All the blades have been sharpened several times by the previous owner. I've been using these blades to cut hardwood but have been getting more wavy cuts than I'd like, despite going slow.
- Aside from cutting straight, what are the checks to determine when a band-mill blade is sharpened and set correctly ?
- Is there a way to tell when a blade is no longer able to be sharpened and set so as to give straight cuts and should be disposed of ?
- Is sharpening a band-mill blade to be 'as good as new' or to consistently cut straight and fast , difficult and time-consuming to learn how to do?
I'm thinking it would be instructive to order some new blades just to compare them with the used blades I have and learn the differences between old and new blades.
I think that all sounds right. I have a setter and sharpener and still working the kinks out. did the setter come with a micrometer to check set? Some new blades will also let you compare the resharpened blades. Other with experience will chime in, I am sure.
As Doc Henderson said... Also there are a lot of reasons for wavy cuts including going to slow. Some new blades are a way to check if it's your blades. If not do a search for wavy cuts, there's tons of posts
CLouie:
Recently MagicMan posted an entry about the width of the gullet on a blade that I think would probably help you. My thinking is if the gullet is too narrow the rollers might be taking the set off of the top side and that would not be a good scenario.
Also what brand blades are you using?
What brand and model number sharpener and setter are you using?
What is the brand and model number of your mill?
Never having sharpened or set a blade I won't be of much help to you but with answers to the above questions and possibly many more some one has probably been where you are and would be willing to help you and most probably others on the FF.
GAB
Here's a link to Woodmizer's Thin Kerf Bandsaw Blade Handbook.
Lots of good info about blades and geometry etc.
https://forestryforum.com/board/index.php?action=dlattach;attach=4532
Much of the info can be used with blades from other sources besides Woodmizer.
Sharpening and setting blades is even trickier than running a mill. You're shooting yourself in the foot trying to learn both at once. You're dealing with so many unknown variables, you'll never be able to accurately troubleshoot issues.
Get yourself a box of new blades. That will accomplish a few things. One, it will eliminate one variable and you can isolate issues to the mill itself.
Secondly, when you are learning to sharpen you will be starting with blades that someone else hasn't already screwed up.
In my experience, there aren't many poeple that can sharpen and set blades correctly. The majority bungle them. And learning on pre-bungled blades would sabotage your efforts in every aspect. So get those new blades.
Good advice from BB above. Personally I find setting to be more tedious than sharpening.
This is one of those situations where a picture is worth a thousand words.
Quote from: chainsaw_louie on May 12, 2025, 08:32:21 AMAll the blades have been sharpened several times by the previous owner.
This is an area of concern (for lack of a better word). I've lost count of how many bands I see that someone has "sharpened" but can't get to cut properly. So far, almost all of them have one of the following two things in common (1 is by far the most common):
1) Improper tooth face grind resulting in either a dubbing effect (lower hook angle than intended due to band being pushed away by the grinding wheel) at the cutting edge or a radius so large that your hook angle is negative
.
2) All the set has been ground out of the teeth
The grinder I have is a Woodland Mills Grindlux 4000.
Tooth setter is also Woodland Mills.
Mill is LT40.
I looked along the length of one blade but didn't see a brand name or model number of the blade .
While I wait for new blades , I'm going to set up the sharpener and setter and see how it works and how precisely I can sharpen and set the teeth.
It looks like the setter with its digital dial micrometer can also be used to measure the set of the teeth without moving them.
do not fiddle much with the sharpener till it is set up. Might be nice if it is really close to where it needs to be.
The basics of band sharpening with a drag type grinder (which yours is) is lightly touch the face of the tooth as the stone comes down, and then lightly grind the remainder of the profile. You may or may not be able to get it in one pass, but keep it light. It's better to grind light and miss some of the profile, and do a few passes. I focus on the face of the tooth, and the back of the tooth. Im only worried about the gullet getting ground to maintain the full tooth height and gullet shape.
Is your setter single or dual tooth? Typically, setters take a bit of fussing with to get them adjusted correctly. Once you do, I would advise you to just go around the blade, only checking an occasional tooth to make sure nothing is out of whack. If you try to watch every tooth, you'll drive yourself insane!
For both operations, your blades need to be clean. And sap build up will mess with indexing pawls, clamps and setter anvils.
https://cookssaw.com/bandsaw-blade-basics-101/
Cooks does a good job explaining blades and their features, etc
D
There is nothing like learning by doing, so today I set up the blade grinder and tooth setter. I watched a video that explained the key points and settings from the previous owner made things go quicker. I was able to sharpen and set one blade:
Set = 0.020 +-
Angle = 9 degrees
This grinder only cuts the face and gullet. Is there any need or advantage to hand file or touchup the back of the teeth ??
I'm forgot to get a measurement on the thickness of the blade which from the data should influence the allowable blade set.
My hp = 28
Tomorrow I'll test the blade and see how successful my sharpening is.
IMG_2212.jpegIMG_2211.jpegIMG_2209.jpegIMG_2203.jpeg
That blade should not have been sharpened & set with that pitch and crud on it.
The best time to clean a blade is before it is removed from the sawmill. Let it run with a good flow of lube or while being squirted with diesel. A wire brush is useful then too.
Thanks for the clean blade suggestion.
I've had good results cleaning circular saw blades using oven cleaner. I'll clean this blade up and re-do the sharpening.
Any comments regarding dressing the back side of the teeth?
With that much crud on the blade it wont saw straight. Steve
Quote from: chainsaw_louie on May 13, 2025, 10:15:40 PMThere is nothing like learning by doing, so today I set up the blade grinder and tooth setter. I watched a video that explained the key points and settings from the previous owner made things go quicker. I was able to sharpen and set one blade:
Set = 0.020 +-
Angle = 9 degrees
This grinder only cuts the face and gullet. Is there any need or advantage to hand file or touchup the back of the teeth ??
I'm forgot to get a measurement on the thickness of the blade which from the data should influence the allowable blade set.
My hp = 28
Tomorrow I'll test the blade and see how successful my sharpening is.
IMG_2212.jpegIMG_2211.jpegIMG_2209.jpegIMG_2203.jpeg
You should set up the sharpener so it hits the face and the tip of the tooth on the way up. Dont worry about the bottom of the gullet, it will hit that after a couple sharpenings. 20 thousands is not enough set to saw straight, set a least 25 thousands, 30 thousands for pine. Steve
As above. The best way to tell if its sharp is there should be no reflexion of light of the very tip of the tooth, hence why you need to grind the face and back of the tooth.
The tip of the tooth tends to round off or flatten when sawing. The longer the blade is run the rounder or flatter the tip becomes aka less sharp then duller the blade. It's a tiny amount but very significant. B
Grinding only the face can lead to a perfectly sharp face with the tip being round or flat. Grinding both face and back of the tooth restores the sharp tip.
I learned this the hard way. I sharpened 5 or 6 blades and the wheel didn't contact the back of the teeth. The blades didn't cut well. Examination of the blades under a magnifier showed round top teeth compared to a new blade.
100% good advice, a sharp tooth isn't sharp just because it's been ground, it must be shaped fully and correctly.
Here is a picture of sharp tooth and a dull tooth, right off the grinder, that I did years ago. At the time, I thought they were both sharp, but not even close. The corners are dull, and that makes all the difference. The best way to see if a tooth is sharp is to get a way to look at it under magnification.
(https://forestryforum.com/gallery/albums/userpics/21488/image~45.jpg) (https://forestryforum.com/gallery/displayimage.php?pid=154944)
(https://forestryforum.com/gallery/albums/userpics/21488/image~43.jpg) (https://forestryforum.com/gallery/displayimage.php?pid=154942)
That gunk on your blade will keep you from ever getting a consistent grind, because the tooth pusher pawl indexes off the face/corner of the gullet. If there is sap buildup, which isn't a consistent thickness, it will position your blade all over.
Sometimes I'll take a "cleanup" pass, just to clean out the gullets without really grinding any steel.
Yes, you need more than .020" set. I'd say .023" at a minimum for hardwoods, and like Steve says, up around .030" for pine etc. I just run .028" for everything.
Thanks for all the good advice:
- clean up the blade
- grind the face and the top of the teeth to make sharp corners on the blade tips
- increase the set to .023-.026
Definitely not there yet
IMG_2216.jpegIMG_2215.jpegIMG_2218.jpeg
I would like to commend and thank you, Chainsaw_louie, for being receptive to the advice being given. Everybody here wants to help, and I for one, (and I bet all of them) appreciate your receptive attitude. These folks are all pros and have metric poop tons of experience and they will tell it like it is.
So a heartfelt pat on the back, and get back to work! thumbs-up
Yellowhammer's photos capture what I was saying.
Yes Mr chainsaw_louie is right for seeking to learn. We all were there once. Some of us, including myself, still learn something everyday.
It was recently mentioned on here somewhere that sharpening only one face of a sawblade tooth is like unto trying to sharpen a knife and only honing/stropping one side.
Most on here know that I have never and will never sharpen a sawblade, but I am certainly a user. My advice is to remove blades when they are no longer sharp. If you wait until they are dull, then you have rounded that tooth tip and you will need to remove more material to regain/recover the tip.
Pushing blades to squeeze that last bit out of them is bad economics.
Made some progress...
Cleaned off what appeared to be a combination of pitch and rust, with a light touch of an orbital sander , only the blade body , didn't sand the tips. Discovered the WoodMizer M4XM label after cleaning the blade.
Next, put the blade back on the Woodlandmills sharpener and played with the settings until I got it to grind the back of the tooth all the way up to the cutting edge. I discovered that the pusher was set up to push the current tooth, I changed it to push on the 1 ahead , the on-deck tooth. This gave me the control needed to reach the back of the teeth all the way up.
I'm hoping that these sharp, square corners are going to make a big difference in how much the blade gets pushed around by knots etc resulting in wavy cuts or straight.
I did notice a bit of blueing on the tips from the heat of grinding , not every tooth, hard to control and not do that.
IIMG_2220.jpegIMG_2221.jpegIMG_2225.jpegIMG_2226.jpegIMG_2227.jpeg
I've been sharpening bands, blades, and cutters for 20+ years and here's my thoughts on what I'm seeing in your pictures.
Quote from: chainsaw_louie on May 13, 2025, 10:15:40 PMIMG_2203.jpeg
IMG_2211.jpeg
Top image looks like you have a negative hook angle. In my experience, this is what I have seen when a customer brings in bands for sharpening and they say "bands aren't cutting". This is caused by excessive wear on both the corner and side of the grinding wheel that contacts the tooth face.
If I increase the size of the bottom image, though I lose resolution, it really appears that the grinding wheel has the same shape to it that I think I'm seeing in the gullet. I would recommend trying either a new grinding wheel or reducing the diameter of the one on the grinder until the side of the wheel is straight (probably close to 1/2" so if you need a radius rather than a sharp corner, put one back on afterwards).
Edit - formatting.
Good point , I'll check the hook angle with a square and angle measuring tool.
Great job. I am a newbie on here, but have that sharpener and setter.
When setting the teeth, bend them a few thou more than you want the final set to be as the teeth spring back a bit. On mine where I have the gauge measuring the tooth from I get 39-41 thou when I set the tooth, and then it is 21-24 when I just touch the gauge to the tooth. I may be pushing on the tip of the tooth where there is maximum spring in the tooth.
With the sharpener, watch the left edge of the grinding wheel. It will wear and not cut to your desired angle. Try and measure the angle on the face of the tooth every 3-4 bands and you will likely see they are closer to straight up and down than having the positive attack angle. You will just need to dress the wheel a bit. You can also upgrade it to the cbn wheel so that you no longer need to worry about dressing the wheel.
If you wanted to try to grind the entire tooth profile, Woodland mills sells multiple cams that are better fits for specific tooth shapes.
I find it is really hard to not blue the teeth tips with a drag grinder. Just take the lightest grind that you can.
There are a few problems with heavy grinds. First, with a vitrified stone wheel, it wears your wheel really quickly, to the point that it might not make it around a blade before it is worn down and changed your grind.
If you grind your gullets heavy, it can cause cracks to start. In my experience, blades air harden if you overheat them, and if that happens in the gullet they will start to crack.
Quote from: chainsaw_louie on May 14, 2025, 06:10:18 PMMade some progress...
Cleaned off what appeared to be a combination of pitch and rust, with a light touch of an orbital sander , only the blade body , didn't sand the tips. Discovered the WoodMizer M4XM label after cleaning the blade.
Next, put the blade back on the Woodlandmills sharpener and played with the settings until I got it to grind the back of the tooth all the way up to the cutting edge. I discovered that the pusher was set up to push the current tooth, I changed it to push on the 1 ahead , the on-deck tooth. This gave me the control needed to reach the back of the teeth all the way up.
I'm hoping that these sharp, square corners are going to make a big difference in how much the blade gets pushed around by knots etc resulting in wavy cuts or straight.
I did notice a bit of blueing on the tips from the heat of grinding , not every tooth, hard to control and not do that.
IIMG_2220.jpegIMG_2221.jpegIMG_2225.jpegIMG_2226.jpegIMG_2227.jpeg
In the fourth picture here, the upper left tip of the tooth doesn't look like it has been touched by the grinder yet. It might be the angle of the picture, as I've never seen it shaped like that. The point I'm trying to make, is that's the corner where the blade engages the wood, on each of the set teeth. The teeth that are set the opposite it's the out side corner. Make sure you are grinding those little corners. It doesn't take much time to just send that blade around again and clean up all the little corners.
"
The teeth that are set the opposite it's the other corner. Make sure you are grinding those little corners. It doesn't take much time to just send that blade around again and clean up all the little corners. "@customsawyer, thanks , I fully agree , the corners must be ground square and proud as per the micro photos posted by Yellowhammer. One more pass and I should be able to hit all the tips fully. I was trying to go lightly and not cause overheating and blueing of the steel, resulting in losing the steel's temper and hardening. This seems to be happening on some of the teeth as in the 4th picture.
@OnParr , re cams from Woolandmills to grind the entire profile , this seems like a good idea , have you used them? The sell 4 specific model of cams for different blades:
- Woodmizer Silver tip
- General purpose
- Ripper 37
- Kasco woodmax
I'll have to call and see which cam profile would be the closest for these WMzr blades I have. One pass to do the entire profile is definitely better than the multiple pass method I'm experimenting with here.
Wlndmills cams:
https://woodlandmills.com/blade-profile-cam/
On my drag grinder, I was never able to get satisfactory results in one pass, it always took two. Also, if the band clamp is not tight enough, the wheel pressing down on the face of the tooth will minutely push the band backward as it is grinding, and decrease the hook angle. So sometimes a heavy cut will not have the same hook angle as a lighter cut. Also, a heavy cut will "de-profile" the stone faster.
Both the shape of the cam and the shape of the stone will effect the profile, and I found that over time, the stone wanted to develop its own profile and instead of fighting and changing that, I modified the cam.
Modifying the cam is pretty easy to do, and I was able to buy generic cams and match every profile I had. However, I eventually just ground to one generic profile for 95% percent of my sawing, and no matter what band brand I bought, they all became that over time.
Grinding bands is very fiddly at first, and that is why so few people can do it well. However, once you get the hang of it, it will become second nature and you will be able to easily know and hear when the the whole process is dead on, and yes, a well sharpened and set band will cut noticeably better than even a new one, so there is a reward for getting it right.
Regarding my hook angle as mentioned by Bradm and Yellowhammer, it seems there is indeed a problem here . I don't have a negative angle but it's sure not 9 degrees either. I'll have to see about the band slipping during the face grinding. Also I need to check if this Woodlndmills RS8 grinder's angle values are accurate.
As for being able to grind the entire profile in one pass, at this point I'd agree that it's not going to be possible with this grinder. Because of the mechanics involved in grinding a corner (back-side & face of tooth) , I can't yet see how to do this except with two passes and two settings.
Two groups of three settings are needed, one for grinding the face & gullet and a second group of settings for the back/top of teeth:
- pusher-advancer,
- depth of cut,
- "stop-plate" for hitting tooth back/top
I can see that recording these settings and switching between the two will be necessary.
This is probably the compromise of this sharpener that more expensive units have somehow resolved .
Picture of my current grind angle and a line drawing of 9 degrees, for comparison.
IMG_2235.jpegIMG_2236.jpeg
Woodmizer has a blade hook angle gauge. I'm very far away from mine right now so a photo isn't possible .
It's a multi-sided sheet metal negative template that is used mostly for identifying the blade. They are quite precise. Eventually you'll be able to look at them and tell.
It would be helpful in diagnosing your angle variation, if there is one. You could eliminate the drawing.
I'm sure other manufacturers have something similar.
From my experience with sharpening, I have rarely ever seen a time when my drag sharpener will grind an entire face of a tooth in a single pass. It is only possible with a CBN style grinder. I have accumulated 12 cams for my drag style grinder. Most of which I have customized to fit specific tooth profiles from many manufacturers. I always plan on a second pass to even up the back of the tooth. I modify the cams to touch all of the gullet on either the first pass or the second pass. I personally don't think it is critical to shine up the entire gullet every time, but as I sharpen for others I find customers buy into the theory that the entire gullet must be ground to eliminate microscopic cracks. It's important to keep customers happy. I do believe it is important to verify accurate set and adjust every time a band is serviced. Often times wood dull bands will be close but metal struck bands will be all over the place. I have found that with the exception of the .055" bands, .025" is the maximum set to use. Over that it requires more power to saw, cause's vibration, and eventually will cause band to break. I have one customer who monitors his band breakage very closely and through experimentation we determined this number to be consistently accurate. I use this theory with all my customers and have had good success. Sharpened 850 bands last year and on track to reach 1,000 this year. Sharpening is not for everyone, but it makes a good retirement income for me.
(https://forestryforum.com/gallery/albums/userpics/20011/IMG_2306_28Small29.JPG) (https://forestryforum.com/gallery/displayimage.php?pid=225136)
Here is the Blade Gauge that Ted was describing above. I painted the 10° White, 4° Green, and the 7° Red. It also has 9° and something else. The section of blade is Turbo 7°, or sometime described as 7-39.
I do not use any of the above since I standardized to the Turbo 7.
Yep, all Turbo 7 for me too. I like to keep it simple. Then WM had to come out with the 747 and also call it Turbo👎
Yes I agree. That additional use of the Turbo word with the 747 could be confusing, and to me was wrongly used. They shoulda just named it the 747 Jet.
I have not and will not try the 747. I am sure that they will cut but that is hanging a mighty pointy tooth tip out there which will surely dull more quickly but at least it is cutting rather than scraping such as the 4° does.
That being said, I sawed over 1MM bf with 10° blades which I suppose have the pointiest tooth tips of all. I tried the standard 7° blades but the deep sawdust carrying gullets in the 7T's win the prize, for me anyway.
Quote from: SawyerTed on May 16, 2025, 07:34:34 PMWoodmizer has a blade hook angle gauge. I'm very far away from mine right now so a photo isn't possible .
Angle gauge is good, but if the wheel has worn an angle on the face the gauge won't expose it.
@chainsaw_louie , can you provide a picture of the grinding wheel as it's currently setup on the grinder?
Today I tested the blade that I've been using to learn the sharpening process with the Woodlandmills tools. Following the suggestions , I've:
- cleaned the gunk off the blade and gotten down to bare metal
- gave it a spin on the sharpener at 9 degrees, grinding face & gullet
- then another 2 spins until all the back/top of teeth were ground
- set the teeth to .020 then per suggestion, re-set to .026 +- .002
The results were pretty good. I sliced up a cant of ash and the cuts were quite smooth and mostly straight, much less wave than I've had in the past. But on the 2nd log the blade suddenly snapped which given that it was quite sharp was surprising to me . This left me with more questions:
- was the set of .026 +- .002 creating too much drag, heat, tension on the blade in ash?
- the tensioner was set to 2400 psi, possibly too much for a used blade with 5x(?) sharpenings ?
Wondering as blades are reused , can reducing the psi on the tension-er prevent breakage without affecting the cut?
At $25 for a new blade, my time and effort to resharpen isn't cost effective but hopefully I'll get better and faster at this. I fully understand why folks dont bother with sharpening. 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. For example, to set a tooth, I squeeze the handle to snug the blade to the anvil but not touch the tooth, then to increase the set the handle is squeezed more until the set is too far but the tooth springs back and hopefully hits the target set or lower in which case a second squeeze of the handles will nudge the tooth to the correct set. Opps , over-set ? , pull the blade backwards and use pliers to bend the tooth backwards , push the tooth back into position, measure and set, repeat, repeat. It's definitely got a learning curve and is part art and part science.
Test of sharpened blade , it snapped soon after this, @&#* !
IMG_2244.jpeg
IMG_2245.jpegIMG_2223.jpeg
Quote from: Bradm on May 16, 2025, 10:56:25 PMQuote from: SawyerTed on May 16, 2025, 07:34:34 PMWoodmizer has a blade hook angle gauge. I'm very far away from mine right now so a photo isn't possible .
Angle gauge is good, but if the wheel has worn an angle on the face the gauge won't expose it.
@chainsaw_louie , can you provide a picture of the grinding wheel as it's currently setup on the grinder?
My experience differs. The guage fits the blade profile very precisely. If the way a blade is ground differs, the variation is very apparent and easily seen.
I would not blame the blade breaking on anything that you did or did not do. All blades will eventually break because they will only go around the blade wheels so many times. Chances are that if you examine that blade closely, you will find some partial breaks.
+1 in Magicman's comment. An occasional blade breaking is usually from blade fatigue over multiple sharpenings. Look close at the break.
A series of broken blades might be indicative of some other problem, like the heel of the blade riding the flange on the guides. I wouldn't go there until something points there. Sawing as much as you did says it's probably cracks in the blade not a mill related problem.
Your set is within the range.
Quote from: chainsaw_louie on May 17, 2025, 12:29:34 AMWondering 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 still wouldn't call the sawing results "good" with that blade. There's a lot of waves. I can see marks from an incorrectly set tooth as well. I don't say this to pick on your sharpening, only to point out that you shouldn't accept substandard results.
I am totally unfamiliar with your setting machine, but here is my experience with mine- I get it set up, which is tedious. But once it is in the correct range, I run the blade around without looking at individual teeth. Mine doesn't have dial indicators on it anyways, but I only check teeth to make sure an adjustment hasn't moved or something. My setter gives very good results like this. I think if you are individually setting each tooth while watching a dial indicator, you'll go crazy!
Get it adjusted to plus or minus .002 of your target, then just run the band around without looking at the dial.
" Both the shape of the cam and the shape of the stone will effect the profile, and I found that over time, the stone wanted to develop its own profile and instead of fighting and changing that, I modified the cam. "IMG_7576.jpeg
IMG_7575.jpeg
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 ?
Quote from: SawyerTed on May 17, 2025, 06:51:37 AMQuote from: Bradm on May 16, 2025, 10:56:25 PMQuote from: SawyerTed on May 16, 2025, 07:34:34 PMWoodmizer has a blade hook angle gauge. I'm very far away from mine right now so a photo isn't possible .
Angle gauge is good, but if the wheel has worn an angle on the face the gauge won't expose it.
@chainsaw_louie , can you provide a picture of the grinding wheel as it's currently setup on the grinder?
My experience differs. The guage fits the blade profile very precisely. If the way a blade is ground differs, the variation is very apparent and easily seen.
I wasn't clear and I do agree with what you said here. What I should have said was that the gauge won't show a worn wheel without first grinding the blade and I want to know what my wheel profile is before I start grinding.
Quote from: barbender on May 17, 2025, 11:08:23 AMI still wouldn't call the sawing results "good" with that blade. There's a lot of waves. I can see marks from an incorrectly set tooth as well. I don't say this to pick on your sharpening, only to point out that you shouldn't accept substandard results.
I am totally unfamiliar with your setting machine, but here is my experience with mine- I get it set up, which is tedious. But once it is in the correct range, I run the blade around without looking at individual teeth. Mine doesn't have dial indicators on it anyways, but I only check teeth to make sure an adjustment hasn't moved or something. My setter gives very good results like this. I think if you are individually setting each tooth while watching a dial indicator, you'll go crazy!
Get it adjusted to plus or minus .002 of your target, then just run the band around without looking at the dial.
Point taken , I should have said "better" but as you point out , there are definite visible waves and nobody wants that.
You guys have been great with all the helpful comments as I try and get my hands around sharp blade issue. It should have been obvious but its now clear that when lumber output is increased via hydraulics & power feed systems, consumable , straight cutting blades are now my bottleneck. I intend to press on and see how much I can accomplish with this WlndMill RS8 & setter but its hard not to get discouraged when I look at the more expensive grinders.
There is a fella on Youtube that uses a pedestal grinder with a shaped stone and in the manner of a CBN grinder, manually feeds each tooth/gullet into the wheel. His speed is quite fast , not sure about his accuracy though .
With a profiled CBN wheel made for dry grinding, it probably wouldn't be too hard to build an accurate grinder using a miter saw or something. But your blades would still have to be clean to index accurately.
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.
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.
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 ?
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.
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.
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.
Quote from: trimguy on May 17, 2025, 05:09:22 PMThese 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".
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.
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
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.
(https://forestryforum.com/gallery/albums/userpics/48503/IMG_3817.jpeg) (https://forestryforum.com/gallery/displayimage.php?pid=359388)
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.
Uh huh - scrap metal...
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.
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.
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.
Quote from: YellowHammer on May 21, 2025, 10:26:21 AMoverall 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? thumbs-up
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.
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🤷
Quote from: Bradm on May 21, 2025, 08:18:53 PMQuote from: YellowHammer on May 21, 2025, 10:26:21 AMoverall 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? thumbs-up
I calculated using metric hours, using centi-minutes. ffcheesy
It's common in Alabama.
Quote from: fluidpowerpro on May 20, 2025, 11:09:11 AMThats 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.
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.
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.
Quote from: TreefarmerNN on May 22, 2025, 06:47:02 AMQuote from: fluidpowerpro on May 20, 2025, 11:09:11 AMThats 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.
Quote from: Ben Cut-wright on May 17, 2025, 10:03:52 AMQuote from: chainsaw_louie on May 17, 2025, 12:29:34 AMWondering 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 ?
IMG_2261.jpegIMG_2257.jpegIMG_2289.jpeg
"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.
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.
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
Quote from: ladylake on May 25, 2025, 04:07:20 AMRunning 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
The WM manual is quite specific that the inner flange-to-blade gap should be 1/16" and the outer 1/8" .
Wouldn't a 1/4" gap allow the band to be pushed back onto the wheels and the teeth start to ride on the drive wheels ?
Quote from: chainsaw_louie on May 25, 2025, 07:07:45 AMQuote from: ladylake on May 25, 2025, 04:07:20 AMRunning 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
The WM manual is quite specific that the inner flange-to-blade gap should be 1/16" and the outer 1/8" .
Wouldn't a 1/4" gap allow the band to be pushed back onto the wheels and the teeth start to ride on the drive wheels ?
No it would allow more room for the blade to run with out hitting the flange.
Running a dull blade will result in pushing the head harder into the log, resulting in the blade running up against the flange. Thus resulting in a broken blade.
The blade guide flange is doing it't job when it stops rearward movement, but remember that the duller the blade, the more rearward movement you have. Properly adjusted Horizontal Tilt pulls the blade into the blade guide when the blade contacts the flange. This does put some stress on the blade but the rearward bending of the blade probably causes more. If your bandwheel tracking is correct, even with 1/4" rearward movement, the blade teeth should not contact the bandwheel.
Dull blades are the principal cause of blade stress.
Quote from: chainsaw_louie on May 25, 2025, 07:07:45 AMQuote from: ladylake on May 25, 2025, 04:07:20 AMRunning 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
The WM manual is quite specific that the inner flange-to-blade gap should be 1/16" and the outer 1/8" .
Wouldn't a 1/4" gap allow the band to be pushed back onto the wheels and the teeth start to ride on the drive wheels ?
The 1/16 and 1/8 gap is way outdated. Back when we ran 10 hp mills and higher hook angles the blade wouldn't push back much, now with higher hp mills and lower hook angles sawing way faster the blade pushes back a lot more. Steve
I'd agree with Ladylake on this one, I put my top two out there kind of taking for granted that everything is properly setup. Touching those guide flanges breaks blades really quickly. I adjust mine just short of 1/4" back.
When the blade is flexing back, it is spread out over a wide area of the blade. When they touch the roller flange, it concentrates the stress in that small area. I wouldn't think it was a big deal if I hadn't experienced it a few times.
The things I watch to see how how dull a blade is, first the obvious if it isn't sawing straight. But then I watch how the sawdust stream is exiting, if it is spilling and making kind of a cloud instead of a nice compact stream, and then at the exit of the cut watch and see if your blade jumps ahead. Its a good visual of how far the blade is flexing back.
Yellowhammer made an excellent video on blade sharpness and things to watch for on his Hobby Hardwoods Alabama YouTube channel.
Well, that's two voices of experience saying 1/4" gap works better than whats in the book, I'll check what mine is set at and make adjustments because I have broken a few blades lately. Granted these are used blades but what you're saying makes sense.
Also, I did get the value of 1/16 & 1/8" from the current , online WMzr LT40 manual that covers the year my mill was made (2013). They could easily update that value and should if 1/4" is better. OTOH , they do sell blades :wink_2:
I checked and the gap between the roller flanges and the back of my blade was 1/16" on both guides:
IMG_2334.jpegIMG_2335.jpeg
I increased them both to @3/16" . Probably they were set too close and caused my bands to break as per your suggestion.
IMG_2336.jpegIMG_2338.jpeg
I could live with 3/16 and 1/8".
No way I could run mine a1/8" back. I'd be breaking a lot of blades. I run 4 degree blades and push hard in tough wood, so a lot of push back. Steve
I believe my manual says 1/8 and 3/16, I set it at whatever is recommended. Haven't had any issues but I only have 25 hp. I can hear it when the blade hits the back of the roller - the few times I have I know "the sawyer" pushed too long on a dull blade... ffcheesy
I'm not fully understanding what , if not the flange, is resisting the backwards push of the blade while cutting. The small settings in the manual seem to indicate that its expected that the blade will be pressing against the flanges. Also, the standard advice given by WMzr and others about avoiding wavy lumber is to avoid cutting slow. Instead cut as fast as possible seems to be the rule of thumb. So, depending on how these factors interact:
- tooth sharpness.
- speed of band in rpm or feet per minute
- speed & forward pressure of blade teeth against wood
- rigidity of the blade ie thick and wide or thin and narrow
...it seems inevitable that as the speed of cutting is increased per recommendations , the gap between the blade and roller flange is going to decrease and the there is going to be contact and bending pressure on the blade.
Is the idea that the crown of the wheels is enough to resist the rearward pressure on the blade and the blade shouldn't touch the flanges or just very lightly?
To my thinking, instead of the blade-to-flange gap setting, the the 4 factors above (band sharpness, band rpm, fwd speed, band rigidity) will determine how much pressure gets put on the flanges resulting in blade stress. But that's just me thinking , you guys have the experience factor and know what actually works.
Thanks.
I think the band wheel alignment help keep the blade tracking in the center, and the guide wheels make the blade flat and have more tension in the cut area. Ideally there is a little room to flex but too much and the blade will start to drift in the cut. the flange is a safeguard but not meant to be used. If it is flexing that much, you are about to break or dismount a blade. I think
@Magicman talked about the tracking of the guide wheels being at a certain slight angle to keep the blade off the flange. My band and guides are all adjusted flat across the face and do fine.
Your questions are valid but a single cut & dried answer that everyone would agree on is elusive. While I may disagree with some of the statements/replies on this topic, I understand them and also the reason for those statements. Our individual preferences are based upon our experience with what we have, what we saw, and with what. Log species, blade profiles, and probably above all, blade sharpness will determine the blade push back.
When a flat blade pushes back, (bows) it has to either stretch or wrinkle. If it wrinkles, it will cause dips and waves in the lumber. Hopefully the blade guide flanges will stop the rearward blade movement and keep it flat and from wrinkling. Proper horizontal blade guide tilt will determine how well the blade guide handles the blade without any vibration.
Remember that the width of the cut enters heavily into this blade push back situation, but there is no substitute for a sharp blade......no....no....none.
My admittedly inexpert knowledge says a properly sharpened and set blade will pull itself into the wood rather than being pushed by the rollers. It's the operators job to keep the carriage speed matched to the blade travel into the wood speed. Too slow and the blade recuts the kerf and starts to wander due to sawmill building up in the cut. Too fast and the blade doesn't pull itself into the cut as fast as the carriage is pushing. Just right and you hear it sing.
I'm guilty of both too slow and too fast at times and pay the price in a thick and thin board. I'm also guilty of running a dulling blade because it's the last log and only a couple more cuts. . . In fact, I'm guilty of a lot of sins with the mill- too many to list, lol.
Quote from: chainsaw_louie on May 28, 2025, 08:01:35 AM- tooth sharpness.
- speed of band in rpm or feet per minute
- speed & forward pressure of blade teeth against wood
- rigidity of the blade ie thick and wide or thin and narrow
...it seems inevitable that as the speed of cutting is increased per recommendations , the gap between the blade and roller flange is going to decrease and the there is going to be contact and bending pressure on the blade.
Is the idea that the crown of the wheels is enough to resist the rearward pressure on the blade and the blade shouldn't touch the flanges or just very lightly?
To my thinking, instead of the blade-to-flange gap setting, the the 4 factors above (band sharpness, band rpm, fwd speed, band rigidity) will determine how much pressure gets put on the flanges resulting in blade stress. But that's just me thinking , you guys have the experience factor and know what actually works.
Thanks.
The four factors you list, and others, are influencing how much push back the blade sees. The flanges are fail-safes to limit
max push back, not meant to be continually forced to control a dull blade or too rapid forward travel. The bending stress is concentrated between the guide rollers when the blade is running hard against the flanges. ALL push back factors must be accounted for when sawing in order to prevent extreme/constant flange-blade contact pressure.
Blade contact is only "inevitable" when factor/factors combine to make it so.
The "crown of the wheel" is a component of blade tracking.
Strain on the blade and resultant friction with the wheel surface is why the blade attempts/continues to track properly when push back occurs.
It's not so much a matter of "
instead of blade-to-flange gap setting " as it is the gap is another factor to be acknowledged. IMO, WM recommendations for flange gap are made considering precisely correct operation using a perfectly sharp blade.
I think two other factors enter in to blade deflection- Band cross section and tension. I've watched YouTube videos that show the blade to flange setting while cutting and the band deflected almost to the flange. I'm thinking it was 1 1/4" x.045. I have since watched mine in a cut and see no deflection at all. I run 1 1/2x.055 bands at the tension recommended by Cook's.
No question about that. Wider and thicker would deflect rearward less, if for no other reason, it is stronger.
I could never opt for .055 thickness because of the 19" bandwheels, but I could have switched over to 1 1/2" wide. I should have done that when I dropped my blade inventory and switched from 10° blades to T7° but I did not and now I never will.
(https://forestryforum.com/gallery/albums/userpics/20011/1CF7AA1B-3151-4C1C-83A9-E019D697684E.jpeg) (https://forestryforum.com/gallery/displayimage.php?pid=269467)
I wonder how much rearward movement the blade on this sawmill has?
(https://forestryforum.com/gallery/albums/userpics/20011/456BE18B-0985-493C-A176-D6341591712C.jpeg) (https://forestryforum.com/gallery/displayimage.php?pid=269468)
I don't know how thick it is but it is 8" wide.
Now think of a double cut mill. One that cuts in both directions. Granted they are a wider blade, normally at least 3", but they couldn't even touch a flange or it would ruin the teeth. You don't want our blades to be hitting the flange either. All it does is cause bad stuff to happen. The blade tension, and the 1/4" down pressure, should keep your blade running where it's supposed to.
Quote from: Magicman on May 28, 2025, 08:42:43 AMRemember that the width of the cut enters heavily into this blade push back situation, but there is no substitute for a sharp blade......no....no....none
This is the absolute. You can not do any of the others without this.
Excellent point, Jake.
Manufactures have figured out how to make better and more precise electrical sensors to measure all manner of things. The gas engine on my mill has a computer and via sensors , measures probably 10+ different aspects of of the engines components and environment.
I would not be surprised if someone at WM isnt working on a control module that measures and computes an optimum cutting speed based on feedback from monitors and values for:
- pressure on blade
- blade temperature
- blade dimensions
- width of cut
- blade tension
- blade rpm or feet per second
Degree of sharp-ness or dull-ness would be a difficult value to directly measure but could be inferred based on the other values .
I'd bet large commercial band mills already have something like this.
I wouldn't be surprised if portable band mill manufacturers are not working adding those sensors. It would be great if they did, but they add a whole new level of complexity and cost.
It's quite surprising how few sensors are used on high production equipment in the wood industry. I know of one company that makes dual position (collar and rim) temperature sensors built into guides for circular saws that will enable the machine to error out before blades bend from overheating.
As far as large commercial band mills go, the ones that I have gone into don't have this. Granted, this is a very small sample size and don't include any high volume softwood operations (highest volume hardwood mills I see is around 25K BF per day). Maybe someone else could weigh in on that.