bandsaw tension guidelines

[Mike Kees]

I just got a blade tension gauge,so now I am trying to figure out what the tension should be for different blade widths.1/4'',3/8'' both.025 thick and 3/4 '' ,.032 thick blades. Just looking for general tension ranges,( my blade stock is lenox if that makes a difference). Thanks for any help, Mike.

[David Kumm]

You will find what works the best for each blade and your saw. I run 25-30,000 on most blades from 3/16-1". My old saws will handle that tension but not all will. Too much can cause tracking problems and bottoming out the spring can lead to breakage. Be sure that you load the gauge and also be sure you go past your tension point and release back down to insure the spring is not fully compressed. Dave

[Ben Rivel]

Shouldnt that information be listed on the blade manufacturers website?

[Chris Hachet]

There will also be a little bit of trail and error in finding a sweet spot with any blade/saw combo in my experience. You will know from the cut what needs to be done to tune the saw.

[Mike Kees]

Ben, I looked on lenox's website and could not find the tension info, hence my post ,Mike.

[Ben Rivel]

Ben, I looked on lenox's website and could not find the tension info, hence my post ,Mike.Well that sucks. Guess Im sitting in the same boat then as I just bought a Starrett 682EMZ and was hoping to use Lenox's recommended settings to get the proper values.

[John K Jordan]

In his bandsaw book Lonnie Bird recommends 15,000-20,000 psi for carbon steel blades and 25,000-30,000 for bimetal blades. This FWW article explains about tension and why higher tension is sometimes useful:
http://www.finewoodworking.com/2012/11/09/setting-bandsaw-blade-tension

I generally tension between 15,000 and 25,000 on my 18" Rikon saw. The tension meter measures the linear stretch of the blade so thick, thin, narrow, wide blades made of steel all stretch the same. However, the actual pulling force for larger blades can be MUCH higher for the same tension, the reason properly tensioning wide blades on smaller saws can over-stress a smaller or less robust saw. Tension is pounds per square inch and a larger blade has a larger cross sectional area. At least this is the way I understand it to work.

From the article link above: "All blades, regardless of width, require the same amount of tension for maximum beam strength. The variable factor is the amount of pulling force needed. For example, it takes approximately 200 lb. of force pulling on a 1/4-in.-wide by 0.025-in.-thick blade to create 25,000 psi of tension. Conversely, a 3/4-in.-wide by 0.032-in.-thick blade will require approximately 800 lb. of force to create the same 25,000 psi of tension."

Years ago I bent the tensioning bracket in my 14" Delta bandsaw by tensioning blades that were too big and had to replace it (I got a stronger one from Iturra Design).

JKJ

[Mike Kees]

John thank you for taking the time to post this reply. I read the article from FWW,that was the kind of info I was looking for. Thanks again,Mike.

[John K Jordan]

John thank you for taking the time to post this reply. I read the article from FWW,that was the kind of info I was looking for. Thanks again,Mike.

I'm glad it was useful. I like Lonnie's bandsaw book a bit more than even Duginski's, although both are good.

Since you have a bandsaw tension gauge you are one step past many bandsaw users with the guessing, trial-and-error, plucking and fluttering, methods I used before I sprung for the gauge. I've been using a gauge (Starrett) for years. I don't always use the exact recommended tension but with the gauge I can at least measure what I have found works and get consistency between blades.

I use my Rikon mostly for green and dry wood processing for turning - often up to the 12" thick capacity of my saw. I also used the gauge to check my Woodmizer and metal-cutting bandsaws. The Woodmizer uses a BIG blade - it takes almost all I've got to tension it.

JKJ

[lowell holmes]

How to set tension on a band saw keeps coming up.

I used to worry about tension gauges and such, but I've been using the "flutter" method.

Google "flutter method bandsaw". Try the method as instructed in one of the sites, it works!

[Van Huskey]

How to set tension on a band saw keeps coming up.

I used to worry about tension gauges and such, but I've been using the "flutter" method.

Google "flutter method bandsaw". Try the method as instructed in one of the sites, it works!

The two major issues with the flutter method is it is not very repeatable and it (the way most people apply it) leaves the blade significantly under tensioned compared to the manufacturer's recommendations and yes, like a passenger car tire inflated to 20psi it will likely get you from point A to point B but it will not be operating at peak efficiency.

I have grown weary of recommending proper bandsaw blade tension, I have come to the conclusion that most people use a bandsaw as a blunt instrument, more a reciprocating saw than a circular saw and thus the quality of cut is not of primary concern.



General recommendations are carbon and spring steel (like the Woodslicer) need 15k-17k to operate correctly, much more than 20k psi and they start to go wonky, you can get away with 8-10k psi on 14" cast saws since thats about all they can muster on a 1/2" blade.

Bi-metal and carbide toothed blades like between 25k and 32k psi, the Lenox Tri-master and Woodmaster CT seem to like right at 30K and the Laguna Resaw King works its best in the 26k-27k range. They all start acting weird above 35k psi but not a lot of saws will get this high on resaw width blades.

I think much of the lack of attention to tension is a result of the fact that (significant numbers of) hobbyists owning saws that have significant tension capabilities is a relatively new development.

[Robert Engel]

I've heard blades can be set by using a tuner. Anyone ever done that?

[lowell holmes]

[QUOTE=Van Huskey;2658730]The two major issues with the flutter method is it is not very repeatable and it (the way most people apply it) leaves the blade significantly under tensioned compared to the manufacturer's recommendations and yes, like a passenger car tire inflated to 20psi it will likely get you from point A to point B but it will not be operating at peak efficiency.

I have grown weary of recommending proper bandsaw blade tension, I have come to the conclusion that most people use a bandsaw as a blunt instrument, more a reciprocating saw than a circular saw and thus the quality of cut is not of primary concern."


I will likely pass a jointer hand plane over any rip cut I make, whether the cut was made on a band saw or a table saw. My table saw has a 10" Forrest blade, so you know I get good cuts.
I don't have a band saw tension issue.

Like the old saying "Different strokes for different folks.":)

[Van Huskey]

I've heard blades can be set by using a tuner. Anyone ever done that?

It has been discussed BUT in order to know what "pitch" to tension the blade to you need a base line for your saw and a particular blade, if you have a accurate baseline measurement just note where the tension indicator on your saw is and record it for that blade. If your saw does not have a tension indicator you could use it once a baseline is determined but the precision and repeatability will hinge on the accuracy of the instrument (ear) you use.

[Van Huskey]

I don't have a band saw tension issue.

[/QUOTE]

While it does not concern you it is very likely your bandsaw is not working in a way that gives you the best cut for the money you have invested in it, if that is OK for you then fine. I think it is important in a tension discussion to point out the flutter method is both low on repeatability and precision and is a poor way to produce accurate and repeatable results. If you not concerned about getting the best cut or the most life out of a blade then accurate tension is unnecessary.

[Edwin Santos]

The two major issues with the flutter method is it is not very repeatable and it (the way most people apply it) leaves the blade significantly under tensioned compared to the manufacturer's recommendations and yes, like a passenger car tire inflated to 20psi it will likely get you from point A to point B but it will not be operating at peak efficiency.

I have grown weary of recommending proper bandsaw blade tension, I have come to the conclusion that most people use a bandsaw as a blunt instrument, more a reciprocating saw than a circular saw and thus the quality of cut is not of primary concern.



General recommendations are carbon and spring steel (like the Woodslicer) need 15k-17k to operate correctly, much more than 20k psi and they start to go wonky, you can get away with 8-10k psi on 14" cast saws since thats about all they can muster on a 1/2" blade.

Bi-metal and carbide toothed blades like between 25k and 32k psi, the Lenox Tri-master and Woodmaster CT seem to like right at 30K and the Laguna Resaw King works its best in the 26k-27k range. They all start acting weird above 35k psi but not a lot of saws will get this high on resaw width blades.

I think much of the lack of attention to tension is a result of the fact that (significant numbers of) hobbyists owning saws that have significant tension capabilities is a relatively new development.

I respect your deep well of bandsaw knowledge. If I might tack on to your excellent comments - part of the challenge here is that a bandsaw operating at optimal peak performance relies on a whole series of set up factors. I feel blade tension and brand of blade seem to always grab the spotlight, but it really should be shared with guide setup, thrust bearing setup, elimination of drift through proper table/fence setup, appropriate choice of blade for the cutting job at hand, technique and feed rate. Some of the tuning can actually be quite personal (think of a musician who uses a particular guitar tuning)

I feel it is challenging for the blade manufacturers to state one single ideal blade tension that ignores the many variables like those above plus the model of saw and it's unique characteristics. Add to this the common "more is better" attitude we have in American society which makes some think more tension is always better. In reality, I was taught that tension need not be any more than it takes for you to get the cut you desire and, with all the other tuning variables appropriately in place, excess tension is not helpful to the machine or the cut. This said, I tend to use a higher tension for the tri-master blade than I do for the carbon blades I used 80% of the time but I don't think I nearly hit the tension levels they recommend because in my particular case I have not found it necessary.

When the bandsaw is well tuned and set up, it can be a very fine instrument. However, if one has not experienced working on a well tuned bandsaw setup, it is hard to explain.

[John TenEyck]

I'm always amazed that people have no issues using a dial gage to set up their table saw but don't treat their bandsaw with the same level of precision, yet then are frustrated by the poor performance they experience. We all know tension is important. Anything short of measuring it leaves you in the dark. I and others have written several times how it easily can be measured with a pair of 6" verniers and two little C-clamps, which don't cost much.

John

[Ben Rivel]

I'm always amazed that people have no issues using a dial gage to set up their table saw but don't treat their bandsaw with the same level of precision, yet then are frustrated by the poor performance they experience. We all know tension is important. Anything short of measuring it leaves you in the dark. I and others have written several times how it easily can be measured with a pair of 6" verniers and two little C-clamps, which don't cost much.

JohnExactly. I think its a cost thing. A dial gauge in a homemade holder to calibrate a table saw is MUCH cheaper than a tension gauge to properly setup a bandsaw. Since there arent nearly as many cheap options for a bandsaw tension gauge and those that are available arent well known, it makes them a lot more uncommon.

[lowell holmes]

When the bandsaw is well tuned and set up, it can be a very fine instrument. However, if one has not experienced working on a well tuned bandsaw setup, it is hard to explain.

Hey guys my saws work great and have been for the past 20 years. I know from experience when the saw is set properly. For you to assume that because some one doesn't use gadgets to set up their saw, well . . . .

You might want to view Alex Snodgrass and Mark Duginske. I might be wrong, but I don't recall either mentioning tension gages.
Google "flutter method bandsaw" and see what pops up.

[Frank Pratt]

There was a thread a while ago, it might be on SMC, about using a digital caliper clamped to the blade with the jaws 5" apart. The blade tension is just enough to hold the blade straight & then the caliper is zeroed out. The tension is then increased until the blade is stretched the correct amount. I can't remember the details & I can't find that thread now. Anyway, I set mine to .003 stretch, which seems really tight, but with a 5/8" blade I'm getting cuts that are pretty much perfectly straight with no drift whatsoever. The saw is a Rikon 10-325.

If I understand correctly, for a given PSI, all sizes of blades will stretch the same amount. The author of the post used Young's modulus & some math to come up with the right amount of stretch.

Found the thread:
http://www.sawmillcreek.org/showthread.php?22144-bandsaw-tension-gauge-crazy-idea&p=198533#post198533

[lowell holmes]

And that article did mention the Timberwolf flutter method. Just saying . . . . . . .:)

[David Kumm]

Generally Snodgras and Duginske are not working with big saws and carbide blades. The $300 blade mistakes can add up. My less scientific method with a carbide blade would be to tension close and test. If the blade spins the back bearing when under load, I'd tighten until it doesn't. I seldom spin the back bearing on a 1" Trimaster. I broke several prematurely when I used to guess at tension and relied on the bearing. When I quit using the bearing, I quit breaking blades. Don't know if the heat created shortened their life, I just know what works for me.354003 Dave

[Sam Blasco]

I know I don't often reply to many threads, but here is one I may be able to add something useful to. I own three bandsaws currently (two MM24s and an old Delta 14 that was my grandfather's) and have had or worked on many others over the past 30 years I've been playing with wood seriously. And, as many of you know, I have helped quite a few folks get their Minimax bandsaws in the last 12 or so years. One of the things I send to my customers when they get a new bandsaw through me is my take on some of the basics, and blade tension gets its few paragraphs. Some of this will be Minimax specific, particularly when I talk about the on board gauge, but I believe it applies to any bandsaw. Here they are (and please keep in mind I don't believe any of this is set in stone, let alone wood):

First and foremost -- Tension is subjective. I think there are decent guidelines out there, but no hard, fast rules to live by. I have experienced good cutting with the same blade at different tensions. The only reason I say this is to free you up to experiment a little and realize you can’t do much damage by picking the “wrong” tension, since both “right” and “wrong” don’t really exist, only variations that approach optimal. You will find the simple on board gauges on most bandsaws are quite, respectably useful and repeatable, and the MM gauge is no exception. I’ll mention more on that later, but first I would like to discuss tension meters, since they and the numbers they provide are much talked about here and other forums, then go into my personal “feel” method. Regardless of width of blade I tension each blade about the same. Obviously, narrower blades require less spring to get to that “same” tension.

There are four tension gauges I have played with: Starrett, Lenox, Iturra and Hakansson. They are all built similarly and use a dial indicator to determine the psi. I ended up owning the Hakansson gauge as it was a gift. There are many other gauges out there, both homemade and mass produced, but these are the four I have experience with. And when it comes to tension there are so many opinions out there about what proper tension should be that I wouldn't know where to start if I didn't trust my own opinion. Ha. I tension by feel, mostly, and that is even more subjective than using meters. According the above gauges (which guys have brought to my classes over the years) I average about 21,000 psi for all my blades, regardless of type. That is the mean based on equal tests with all four systems, following the manufacturers instructions, as the numbers from one gauge to the next varied considerably (about a 3,000 psi range between the high reading and the low reading. 21,000 psi is fairly moderate tension compared to some of the large numbers that many professed experts have claimed are necessary and have debated about for years (15,000 – 20,000 for carbon steel and 20,000-30,000 psi for bimetal, which would include most carbide tipped blades). Does that mean I am debating now? All tests were done to my pencil line drawn on my on board gauge that I have used reliably for years to tension my blades. Each tension gauge agreed with itself, at least, when tested three times - within 1,000 psi). What does this tell us? I don’t know, but it leads me back to my method...

Come 6" down from the upper wheel, where the blade is about to enter the tire. Tension enough so that there is less than 1/4" deflection with moderate pressure (no body weight behind your finger). Track the blade where you want it. Close the doors and turn on the machine with no guides set and no zero clearance dust block. Check the blade to make sure it is not fluttering side to side. If it is, add a little more or less tension while the saw is running until the blade stops fluttering. Make a test cut on a 6" resaw. Does it cut easy? straight? no wander? If so, you have found a good starting point for tension. Draw a pencil line on your saw's gauge and you can return to that setting reliably for that blade again and again. A 1" blade will require the same tension as a 1/4" blade, but will use much less spring to get there. I have three pencil lines on my saws... 1", 1/2" and 1/4". Typically, for a 1" Carbide Tipped blade, the pointer will be about 1/4" above the last line on the saw’s gauge, or 5/8s of the way up from the bottom of the window. The picture below of my on board gauge is just to give you an example of about where the pointer goes, your own results may vary. The 21,000 psi is between those two upper lines and if I add enough tension to get the pointer just above the top line I'm at 26,000 psi, according to those gauges I mentioned above. The saw cuts very well at both of those points, so I like to err on the side of less tension (this goes for drive belts too). The results confirm my theory that a blade will cut well at many different tensions, and go in and out of "flutter" at many different tensions, too, so beware of the "flutter" test as a sole means of tensioning a saw. Harmonics is an interesting subject. I like to run my blades at the lowest tension they cut well at, since I believe there is no point in over-stressing a system. Would you run your car at the RPM red line all the time because the engine is capable of that? Why over stress a system if you don’t have to. If you feel you ever need more tension for a particularly hard task you know you have some in reserve, right? As for the pointer, itself, you can actually adjust it to point wherever you want it to when you reach a tension you like. Unscrew it from the frame and access the spring and its set screw from the backside. Personally I find it easier to make a pencil line.

354011

[David Kumm]

Good stuff from Sam. I'm not surprised that the sweet spot on his saws is lower than what I consider it to me on my old cast iron frame saws. The characteristics of steel vs cast iron will be different and I should have included that I run Oliver 116 and 217 and a Yates Y20. They also don't have built in scales that are very consistant - or exist at all. Dave

[William Shelley]

Hi all, first post here on SMC.

I've been working on-and-off on a shop-made 19" bandsaw with wood wheels and frame. I decided to go with pneumatic cylinders for tensioning. Pneumatics are really the best way that I found to apply force to the blade. A 4" bore cylinder can apply 1759lbs of force at 140 PSI, divided by two (force applied to wheel is divided over both parts of the blade) gives you 879.5lbs which is good for a 3/4" bi-metal blade.

In a test by Matthias Wandel, he found that the spring tensioning mechanism is hardly able to apply more than about 65 pounds of force, barely enough to tension a basic 1/4" blade.

My saw was designed from scratch to use a pneumatic tensioner but you may be able to retrofit it into an existing commercially-made saw. The great thing is, you can dial the air pressure way down, for example at 10 PSI, the same 4" bore cylinder puts out 125lbs of force, or about 62.5 pounds applied to the cross section of the blade.

[John K Jordan]

Hi all, first post here on SMC.

I've been working on-and-off on a shop-made 19" bandsaw with wood wheels and frame. I decided to go with pneumatic cylinders for tensioning.

That is interesting. Do you have any pictures of your saw and/or the tensioner?

How in the world do you keep the pressure constant? Do you think a small hydraulic cylinder would work?

JKJ

[John TenEyck]

Wendell's spring mechanism must have been sized for a really small blade - or maybe he just got it wrong. Springs can put out all the force a bandsaw needs if it's sized correctly, which is easily proven with a tension gage. An air cylinder would be great, to be sure, however.

John

[William Shelley]

That is interesting. Do you have any pictures of your saw and/or the tensioner?

How in the world do you keep the pressure constant? Do you think a small hydraulic cylinder would work?

JKJ

Here's an old link to my project. It looks a bit different now, and the wheels shrunk to 19" because I didn't oversize them enough when assembling.



The wheel mounting assembly has been tweaked a bit as well.

The really nice part about a pneumatic cylinder is that a cheap regulator is all that's needed to keep the pressure constant. Hydraulics would work as well, we have a really large vertical bandsaw for cutting steel beams at my workplace (it will cut a 24" x 6" x 1/2" I-beam like butter), which uses a hydraulic tensioner. I prefer the pneumatic for my bandsaw because the air can act as a shock absorber.

[John K Jordan]

Wow, you gotta applaud a guy who builds a bandsaw from scratch!

JKJ

[Myk Rian]

While it does not concern you it is very likely your bandsaw is not working in a way that gives you the best cut for the money you have invested in it, if that is OK for you then fine. I think it is important in a tension discussion to point out the flutter method is both low on repeatability and precision and is a poor way to produce accurate and repeatable results. If you not concerned about getting the best cut or the most life out of a blade then accurate tension is unnecessary.

Sounds condescending to me.
I've used the flutter method since forever. Always works, and is repeatable.
I can set my Delta 14" w/riser up in a couple minutes and resaw 12" planks.

[Mike Kees]

I originally asked the question that started this thread,and received the answers that I needed to effectively use my tension gauge.I do not consider myself an expert on bandsaw use and setup yet. As such I have read every thread on SMC on bandsaws for the last few years. I very much appreciate Van huskey's knowledge and his willingness to share it. I think that a bandsaw is one of the most rewarding tools to use when everything works well,and one of the most frustrating when one is trying to get it figured out. I now have far less questions and more answers about my saw,thanks to SMC. Mike.

[Edwin Santos]

I originally asked the question that started this thread,and received the answers that I needed to effectively use my tension gauge.I do not consider myself an expert on bandsaw use and setup yet. As such I have read every thread on SMC on bandsaws for the last few years. I very much appreciate Van huskey's knowledge and his willingness to share it. I think that a bandsaw is one of the most rewarding tools to use when everything works well,and one of the most frustrating when one is trying to get it figured out. I now have far less questions and more answers about my saw,thanks to SMC. Mike.

Hello Mike,
For whatever assistance it might provide, here is a link to a FWW video featuring your fellow countryman Michael Fortune that talks about bandsaw setup. Michael is a frequent contributor to FWW and has earned his own reputation in the woodworking world. I had the opportunity to take a one day bandsaw class with him and while he went into much greater depth than a video will allow, what he shows in the video is what he showed in person. Where the controversy arises is that he is in a different camp of theory than many of the other authorities on bandsaws, especially on the subject of the need for high tension.

I'm not sure its so much a matter of one being right and one being wrong as such, but I came back to my shop and decided to try what Michael advocated and see what happened, and the results have been excellent, so now I'm a believer. In fact, I was considering "upgrading" my 18 year old bandsaw until Michael's class, and now I've dropped that idea completely because I'm no longer sure what I'd gain.

Also, from a standpoint of technique, his instruction on curve cutting with accuracy was a big game changer for me. Perhaps you will find it helpful. If you ever get a chance to take a class with Michael, it would be worth every penny. He's also a master of devising very inventive jigs for use with the bandsaw.

Here is the link: http://www.finewoodworking.com/2011/04/07/how-to-set-up-a-bandsaw