Bandsaw chatter, modifying tooth set, and making precise cuts
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- Опубликовано: 10 сен 2024
- Experimenting with different blades and bandaw chatter, then modifying the most troublesome blade to have less tooth set, which, though it didn't solve the chatter problem, greatly improved the cut quality. The main culprit to chatter is too much of a hook on the blade.
woodgears.ca/ba...
One of my favourite bandsaw stories was from a friend who worked in a store that made custom bandsaw blades. Ralph was at the back of the store when a disgruntled customer came in yelling from the time the door opened. Ralph had made him three blades and they were all backwards. He had travelled from an adjacent island and driven a ways to complain (no phone call) Ralph listened, took one of the blades and flipped it around and the guy turned on his heel and was never seen again.
He, he. feels so wrong to laugh at something that is so good to laugh at.
A few years back, I had a neighbor that decided to install a surveillance camera at the entrance of the house. Less than one hour later, he was back at the store complaining the camera was faulty and the image was upside down. The guy on the store, picked up the camera, rotated it on his hand and said: this is the way you have to install it!
@@JoseSilveira-newhandleforYT I would have told him that his TV was installed upside down, and to flip it over.
@@spokehedz LOL. That might have worked too :-)
That guy became the laughingstock for a long time and I don't know how far it went, because the owner of the shop told the story to all his suppliers (may have reached the manufacturers too). In the electric and electronic business, a blunder like this is priceless :-)
@@JoseSilveira-newhandleforYT all PTZ cameras I buy have a built in FLIP sensor to rotate the image... automatically.
guess your neigbour was used to good cameras.
Matthias' videos are the type that you always come away from it a little bit smarter each time.
This one is worth it for the "following the curve with the back of the blade " tip alone :-)
That visualisation with the large boards and the drawing of the blade profile was really clear!
Always a good day when Matthias drops a video
YOU CAN GET SOME OF THE RADIUS BACK! I have done this trick, pressing a grinding stone on a running blade. Angle the stone against the blade's trailing edge to round it over. It looks microscopic but it really can reduce the minimum radius in curves, and also reduce some of the running friction of the blade in the cut if your tooth set is especially shallow.
Matthias has shown this trick before, IIRC
Instead of silencing them, try to listen to their needs. Remember, the key to a good relationship is open communication. And who knows, their chatter can be insightful. 😉
😳
While you are stoning the set, it's a good idea to stone the back edge of the blade so it rides smoothly on the thrust bearing.
Always great content, thanks for sharing.
Cheers
I didn’t understand all of it, but it’s a lot more than a knew before, so thank you for that.
Got to love the honesty.
Ditto!
My first guess was that you were just going to toss the blade .. cause that's what I'd probably do. So it cracked me up, and made more sense after thinking about it, when you got into ways to fix the blade. Thinking it was combination of your engineering training and your upbringing ... which is what made more sense.
You must be new here. Because Matthias does not toss anything. He'll work on it until he fixes it.
You do a great job of explaining what your conditions are and how the blade design and wood contribute to the results. Also your solutions are based on your experiences and results (evidence based learning). And yes, I have seen you stone your bandsaw blades before.
What makes your videos very special (at least for me) is this scientific but yet simply explained approach 👌
Nice to see that Rachel is still following her strict hearing protection policy 👍🏻
WHAT!?!!?
Reducing the set as you have and "stoning" the blade are techniques that work well, in my experience. I stoned the blades as you did without reversing the blade and everything worked out fine. I think blade tension might also be a slight factor, because smaller blades can't tension as much as larger blades. Just one person's experience.
Great video. Thanks.
After all this videos and seeing Matthias cut al sorts of curves perfectly with the band saw he revealed his secret! Use both ends of the blade! Thank you for sharing Matthias.
It's blade tension. The blade is being pushed back until it can't anymore. Then it cuts deeper and jumps forward. These larger band saw systems require a good more tension.
"I can touch the running blade because it's backwards" - just don't push too hard!
What are you doing here? Just watched your baby nvme video. Slightly change of tone from your other videos but educational regardless.
Helo i am from indonesia
Red shirt Jeff? Is that you?
Great video content as of late. Like days of yore.
yes, but unfortunately only half the views of yore.
@@matthiaswandel Much more competition than in the days of yore.
@@matthiaswandel I blame ad fatigue, youtube are destroying themselves
@@matthiaswandel I'm now watching your videos twice ...every little helps
@@juleswebb1885 on one of his recent builds (chairmaking maybe?), he referenced that the money he makes from watching ads on a video is nothing, like a cent per view, so if you want to support him, buy a single plan for $5, and that'll be more than he'll make from all your ad watches for all time.
Would changing the speed of the motor improve the blade's performance?
I'm thinking the same. Maybe it's going too fast. Looking at the slow motion we see that the blade is pushed back and all the teeth slide and are not cutting, until the pressure is enough to overcome and then one of the teeth bites in and jerks the wood.
@@Tweogan No, its going toooo slow. Optimal speed of blade is around 30-35m/s. He has around 10 I think, from previous video.
I really appreciate these kinds of videos where you show your experimental process.
Not gonna lie, I winced a bit when you put your finger against the backwards blade - even though I knew it was backwards. Fast moving, even blunt metal cuts skin quick!
I use 4 TPI skip tooth to get good smooth cuts and faster than a 6 TPI, 3 TPI is great for resawing and that is about it.
4:16 normally I would have been shocked, but I've already seen John Heisz split a blade in half with an angle grinder while the saw was running.
Eres mucha pieza Matthias gracias por tu humildad y por compartir tus vídeos
Barbaric setup for Matthias = Very advanced setup for most woodworkers
Nice video. Was interesting to see the process of diagnosing and addressing the problem set along with the gauge and camera shot.
The tooth set reduction will leave your cuts just a little smoother but will not fix the issue at all. Steep hook angles and low TPI blades are for rough ripping applications. The only thing that will offset the low TPI/hook angle is ramping up the rpm of the blade my 1.25" x 158" have a 7/8" tooth spacing with a .025 set and runs at 5800 fpm and unless I whack something in the logs and break a tooth or throw a tooth out of set, the cuts are planer smooth.
Still no mention of a lack of rigidity as a potential source of the grabbing problem?
the wider blade, being more rigid, probably helps. Though it also has a bit less hook to it.
@@matthiaswandel Any thoughts on tensioning the blade... increasing it on the chatty blade?
@@matthiaswandel I mean the rigidity of your bandsaw frame.
@@beefchicken I think it is just as rigid as a cast iron frame. Didn't he check that out? It looks pretty rigid to me. Anything C shaped with a 26" span will have some small amount of flex. But I think Matthias showed previously that wood built up to an appropriate thickness can be just as rigid as cast iron. Anyway I trust Matthias to correctly diagnose what is going on.
I use butcher's bandsaw blades. 6tpi, very little hook. Nice clean cut. Well able for hard ash.
Have you tried cutting without the table and going directly off the frame? Wondering if the table has some bounce or weird modal response since it's bigger than your other saws. 0:46 trying to find nodes in the sawdust like a chladni plate. Since the table has a long slot for the blade, it's basically a big tuning fork.
Matthais, it may be something you never do, but I find that a high set blade is very useful when cutting round work in green wood (bowl blanks for instance) this seems to stop the blade jamming (most of the time !)
That blade does not appear to “lunge forward’ but rather, seems to come back to vertical, where is your rear guide in relation to the blade at rest ?
I have never dressed the tips in that way, interesting, I always take the arrises off the back of a blade,I think it makes turning the blade in the cut easier.
A glance through the comments and I didn't see one like this. I've had saw chatter but never seen a blade pulled forward until this video... and then again just a few days ago on my Delta knock off bandsaw. I'm planning some resawing - quite a lot for me so I purchased and Olson 3/4" 3TPI blade. It behaved much like Matthias's blades. It pulled the blade away from the back bearing and towards the metal insert on the table which was a bit alarming.
My solution was to re-adjust the tracking with a bit more force back towards the back bearing so the blade made more constant contact. YMMV.
I'm not entirely sure if this was just a new observation or if it was a new phenomenon. I sure don't get those kind of lovely smooth cuts on my saw but resawing ends up in a thickness planer anyway.
I guess you need to resharpen those blades with less hook. Also, passing the blade through 2 side by side large diameter bearings, mounted on a stiff base (metal), will force the teeth to a lower set in a faster way, and making the distance between bearings adjustable, allows testing for the best results.
Great analysis as always. I'll put a new blade on my bandsaw next week!
A lot of people don't build\use hobby CNC because they are practical or sensible, but because there is a certain joy in the process. I mean, who would ever build a bandsaw when it only takes 15 min to order one! :D
I personally would enjoy a Wandel twist applied to a CNC machine of some sort. At the VERY least, it'd be good for content.
Matthias, what does the weld area look like? Is it welded square and was the weld ground smooth. Just wondering if that could be the cause of some of the chatter and jumping.
Is the blade running too slow? the top wheel is the largest of all your bandsaws, its like the big chainring on a bike, the blade is moving more slowly. Can you get some type of variable speed drive for the AC motor that would enable you to run the motor faster? Can you test the blade on a smaller bandsaw?
Well done, great toys for you😀👍👋
I would suggest using smooth faces on the vise along with a calibrated torque gauge on the jaw handle, in order to perfectly align the set of the blade's teeth along with a preheating process in combination with a laser actuated temperature gauge in order to avoid getting the blade too soft. In this manner, one might conceivably set the blade's teeth to within 1000th per inch accuracy, along with a timed, progressive feed into the jaws of the vice, consistent to the 100th of a second. This might be done by very meticulous elves who have experience in these matters.
Otherwise you could simply file the teeth down in just the manner that is shown in this video.
Thanks for the content.
Keep up the good work. בס״ד
Could you build a whirligig...curious to see what you come up with
will the deep hook blades
become better as you wear them out?
Probably less chatter. And I figure after the first sharpening the chatter won't be as bad either.
You should give the wood slicer blade from Highland wood working a chance, They are great blades. very smooth cut
I would also expect blade tension to affect the chatter. Did you test that? I once started my bandsaw after I forgot to RE tension. Was surprised by the amount of chatter.
Yes, tried that. I figured if I ran it hard against the trust bearing, with the guide close to the blade, and more tension, that should help. But with a quick test I did, it made no difference.
Very crafty thinking in this video. Practical or not I would love to see a wooden CNC machine from the original wooden machine master himself.
I have worked in a saw shop in a modern sawmill for several years and i think that the most likely reason for the thin blade to move in the cut like it does it the back of the blade on is not straight. Put a long straight edge against the back of the blade near the weld and in several places along its length. I am sure you will find that most areas of the back are flush to the straight edge and near the weld it it bowed in or out. We had the same problem on our large 10"X38' band saws. I am not sure how to fix that on a blade that thin.
"I will fim it with 600fps with this camera .... but at really low resolution" ... xDDD
You really earned that subscription with this and some of your other vids, and your other channel. :)
"Cnc takes longer if you factor in the time to program it" Yep. For one off productions cnc is usually a waste of time. That being said there is some new scanners coming out, cheaply and therefore more common to find, that make part duplication via cnc actually quicker..which can also be a problem.
As for blades, a properly ground blade cuts very well for a long long time, there is also another factor to bandsawing. Dust. If the blade speed is too slow on your bandsaw the dust collects intermittently jamming the blade. Ive noticed this as it sounds like the blade is broken or hitting something. Very noticeable when I cut green wood.
Nice
i have a question about tooth shape
most of my jigsaw blades slopes inward, and you draw bandsaw blade tooth sloping outward and being well full thickness of the blade not pointy from either side
so how does a bandsaw blade cut? does it carves, slices or scrapes the material? because we have possybility to sharpen it as either one as a row of basically knives, chisels or hooks/scrapers
Is it just not worth it to reduce the hook angle with a grinder or file or something?
Nice explanation , waiting for an automatic bandsaw sharpener with more wooden parts.
Do those blades chatter on a normal bandsaw? Maybe the saw itself is not stiff enough, flexing in the table and supports, etc. Just a thought. Great videos, thanks !
If the shape of the tooth hooks into the wood and grabs the blade, would increasing the speed help ? If the tooth moves so fast that it cuts on it's way without having the time to actually hook to anything ? What happens if you increase the size of the pulley on the motor to increase the speed ?
Very interesting. I'm enjoying your sleuthing on The Case of the Chattering Bandsaw.
Two things I wonder about are how blade tension affects the chattering issue, and how the blade width and thickness affects the chattering issue.
I'm thinking at the instant the blade begins its aggression into the workpiece, the blade is still suspended in nearly the same 'track' on the wheel. It must be bending toward the workpiece. How do the width and thickness of the blade play against this bending?
What's the process for setting blade tension? Is it the same for all 3 blades, wide, 3/8, 1/4? What if your tensioning process unwittingly favors the blade that seems to chatter least?
The blade's aggression into the workpiece reminds me of how chainsaw chains are designed. Each tooth has a very aggressive cutting attitude, but each tooth also has a depth gauge that limits the material removal rate of each tooth and prevents this aggressive diving in that you're experiencing.
What if you consider a blade that causes you this chatter problem due to this aggression, get blade that's exactly the same except twice as many teeth per inch. On that double TPI blade effectively disable every other tooth from cutting. Those disabled teeth would be like depth gauges on a chainsaw chain.
I just rewatched you building the wheels for this bandsaw. Since the wheels are 26" diameter, there is a good 80" of blade in contact with the wheels continuously. The stiffness of the wheel and its parts are going to contribute quite a bit to rigidity. With such a large percentage of the blade in contact with the wheel, what seems like a lot of blade tension is divided along a lot of wheel surface. So the inner tube rubber isn't really being compressed much. This makes me think it's got more to give and may contribute to instability when made to work hard enough. The wider blade covers more rubber so its pressure per square inch is further reduced allowing for more sponginess. The narrow blades may better compress the rubber, but it looks like you didn't glue the rubber down, so maybe the blade and rubber are slipping or walking? Maybe consider a harder thinner rubber tire material and glue it down? Perhaps you did glue it off camera? Anyway, just some thoughts 🤷
One question. Will the bandsaw wheels fill up with sawdust because you didn't make a groove for the inner tubes?
Is it possible the motor isn't fast enough. 3450 rpm
Where did u get the old camera that records at 600 fps?
So, when you will build your first CNC machine?
CNC wastes too much material. Maybe he shouldn't have said "imitation CNC", it's the other way around. CNC, in his use, would be an imitation bandsaw.
Hi Matthias, I’m curious about the tooth geometry of those blades. Larger blades with less tpi generally have rip teeth, smaller blades with more tpi generally have cross cut teeth. Cross cutting with a rip tooth profile will be jumpy.
Have you examined the tooth profile?
Rip teeth are more like a chisel at 10 degrees, crosscut teeth are more slicey at 35 degrees.
Thought he mentioned a lil tikes height gage instead of low tech. I now want a lil tikes set of measurement tools.
Is spring tension on the upper wheel another variable that should be factored in?
what would happen if you inverse the leading edge to make a v instead of a point? in total the cut would look more like a M shape looking down on it. having a more angles leading edge might cause it to cut easier under low feed(low pressure) but let it cut more under high feed.
I really wonder how a variable pitch blade would do.
When you grind the sides of the teeth, it makes the blade sort of like a hollow-ground blade, no?
How much do you pay for blades? I got two made for mine 1/4 or 6mm 6tpi for €22 why sharpen at that price ?
Mine cost more, but mine are possibly almost twice as long as yours.
Fair point mine are considerably shorter (2560mm). it's been a brilliant build very enjoyable👍
@@matthiaswandel There's something to make. A CNC blade sharpener.
No chatter with smaller bandsaws and similar tooth? Maybe the lighter wheels on this one may have some thing to do with that...I guess there is a way to find out.
Will the speed of the blade change how it cuts? like if you made the motor spin faster or slower (if that's even possible, I'm just curious lol)
Would be interesting with a comparison with a metal bandsaw and see how much the chattering is due to the frequency/softness of the wood that the bandsaw is made of.
Exactly what I was imagining, the wood has a harmonic frequency that sets up a sympathetic vibration with the walls of the structure, which also could effect the stability to the extent that the blade's chattering has caused the wood to chip out whenever that type of wood is being used. Theoretically, this harmonious vibration could cause Matthias's spectacles to crack - but they are most likely plastic, not glass, so we should not have any worry of this.
Putting the blades in backwards was a very barbaric choice, however.
Maybe I missed you talking about it, but what's your blade speed? Is that effecting the cut quality?
This is a bit long, so if you think it's inappropriate feel free to delete it.
Watch your slowed down high speed footage and pay attention to the close up after the blade exits the sapwood and starts into the heartwood. Walnut is semi-ring porous or semi diffuse porous wood. Either name is correct. Notice also that the chatter is not consistent in singing tone. Now note that the forward bound occurs when the blade clears the dense ring and is rapidly pulled by hook to advance into the porous ring. Keep watching and notice how the rate of bounding forward will change as the angle of the dense and porous wood change as you cross the board from quarter cut to rift cut to flat cut.
WRT to the narrowest blade being the most problematic with its hook tooth, the ratio of the tooth set to width of blade is quite high (as far saw blades go). Just as this fact lets you cut a tighter radius, it also subjects the blade to being pulled to the side by an aggressively hooked tooth. With coarse TPI the blade will tend sing as it oscillates, but finer TPI with its proportionally smaller tooth will be pulled less before its counterpart pulls back the other way.
Before setting a tooth has neutral edge with respect to the depth, front to back, and with respect to the length of the body. The machine "stamped" set of a fresh new bandsaw blade is now not optimal. As a tooth is set, the cutting edge of the face of the tooth is now in a negative rake as your expanded diagram illustrates. This property of the tooth, properly called the "fleam" has to be corrected as with a handsaw. The leading edge of the tooth sideways and forward must be the most prominent point, and must have a slight positive rake. This can be done very easily and quickly with a Dremel tool and a diamond disc. The right fleam will cure these oscillation and bouncing problems. However, ripping blades should have a neutral fleam and not negative.
Less oscillation results in a smoother cut. If this oscillation didn't take place we would have bandsaw cuts as smooth as table saw cuts!
Do you get the same chatter when cutting with the grain rather than against it?
Hi Mathias, Leo from Tally Ho had wood saw into boat lumber, see : Milling live lak in th deep south, the man who owns the Mill tells a lot about saw blades, greetings from Amsterdam
I think you meant "milling Live Oak in the deep south"
Isn’t it the hook angle of the tooth not the set that makes it lurch forward into the wood. The aggressive set would certainly cause it to leave a rough cut surface. How did those blades cut with the grain? I bet they would be great for ripping on a very small scale sawmill per say.…
Is the blade guide too weak or springy somehow ? Or maybe one of the guide bearings has too much clearance.
Oh, now i see what "hook" means. That seems to be more of a problem because it's pulling the blade forward into the wood.
It's a bit like drilling brass - you just don't want to much "hook" on the cutting edge.
Very interesting, Matthias. Do you think there is any flex in the large table that could contribute to this chatter issue?
I had a double-take on the video photo - what is Matthias doing with all the tongue depressors?
I'm not sure what TPI is and at this point I'm too afraid to ask
Teeth Per Inch
What about the sparks that go down into your sawdust drawer?
Excellent.
Its the weirdest thing. At 1:18 I didn't see the blades lying on white paper, I thought I was seeing a mocked up blade profile constructed with white paper. I thought M was going to give an object lesson as he had done in the past with props. It wasn't until 1:37 I realized it was actual blades lying on a white background. (I really was wondering why the white blades had rounded teeth..lol).
I think for such long band its safe to say that bldes you use are far to elastic, and something intended for sawmills would serve better in this long span
One of the ways to get a backsaw to cut straight is stoning one side of the saw, so why not for a bandsaw?
What will happen if you increase the Speed of the Blade
Another excellent video!
CNC is great for production and precision but for one-off parts, it's usually not worth it unless precision is required. Still fun to play with though, as a hobby.
I would expect that the narrow width of the grabby blade to be a important variable. Narrow width equals more flex at the cut. Same with the length of the blade, more length equals more flex. Wouldn't a shorter and/or wider blade with the exact same tooth profile grab less and cut cleaner?
Makes perfect sense to me. The blade guides can't stop forward movement, so the more distance between wheel centers, the more the blade can move in the forward direction, regardless of how low you place the blade guide. I also wonder if the wheel curvature is a factor. These wheels were made to be able to take really big blades, but maybe that leaves them a bit flat in the middle, for running thin blades. If the wheels are wide and flat, the blade can walk forward without as much bias to stay where it normally tracks.
FWIW, I only tried a hook blade once. And it happened to be a 1/4" width, 25 thous thickness, at 4 TPI. I loved it, compared to the 6 TPI blades I had used until then. I don't remember it chattering like this. But it became the first and only blade I ruined by jamming, when it grabbed and flipped a small piece I was cutting out of my fingers and into the blade. I been using low TPI blades ever since, but without the hook.
Any clue what your surface feet per minute is?
Thanks for sharing those tips!
Isn't the problem related to slow speed and blade tension?
When I run 6-8tpi blades I always manage to wreck them before they go dull. At least it fixes the sharpening problem...
Where do you get quality bandsaw blade in Canada. Where I ordre my I always have problem at the soldered joint.
I buy from sawlutions.ca, but as you say, sometimes the weld isn't great. Sometimes it is though...
I have lightly touched my diamond hones to the my bandsaw blades a wee bit, gives smoother cuts.
Great information as usual
Vem pra o Brasil da aula de carpimtaria.
Cnc blade sharpener?
Thanks.
maybe you're running the 4 tpi blades too slow? and thats why they chatter?
very interesting.
Does the hook on the blade cause the same issues on your smaller bandsaws? If not, it would be interesting to know why this problem arose on the larger saw? Perhaps you've reached the rigidity limits that a wooden frame can provide?
I don't have one of those blades for my smaller bandsaws
@@matthiaswandel Thanks for replying! It's just that these blades looked fairly normal to me. Did you compare the hook profile of these blades to the blades on the smaller saws?
Woodworking and topology in one episode!
Where i can get this kind of saws
I was naive enough to assume that manufacturers had studied the science and engineered their product to a point where any blade you purchased would not have this problem. A cheap blade may not stay sharp as long as a higher end one but it seems that the blade design should be sufficiently similar that they both give satisfactory results, at least while new/sharp. Let’s hear from viewers if they have observed this problem with their bandsaw blades. 😎👍👀