bandsaw blade question

[terry mccammon]

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Background:

All I ever use my bandsaw for is either cutting up logs for turning stock (soaking wet, up to 14" cuts), cutting up dried stock, or cutting out carving blanks. I have about a 1/2 clue what I am doing as far as blade tension, etc. I use the so called flutter method, which seems pretty sketchy to me, but what do I know. Too lazy to measure the stretch and apply Young's modulus. I am not ever buying a tension gauge and don't have the sort of musical ear that I can pluck a saw blade to determine proper tension. The tension gauge on the saw does not work. I have a Laguna 14 SUV, which due to the 3 HP motor I really enjoy. I am careful about the blade setup so far as balance on the tires and blade guides go. I have never stalled a blade. I always release tension on the blade at the end of a session. I am not a mechanical engineer but I wonder if the application and removal of tension stresses the blade, but I am worried about the tires as I cannot imagine what replacement of a tire would be.

I always simply bought the cheapest blade I could find as cut quality, etc. were meaningless in my use. I always buy a 1/2", 3 tpi, hook. Last Spring I popped for a Lenox bimetal Diemaster 2, 1/2, 3tpi, hook blade as I had read about long life and all that. I will say that I noticed an immediate difference, in cut speed and general utility. At around twice to three times the price.

It broke yesterday after around 5 months of use. Not particularly heavy use as I have not processed all that many logs, or not all that many so far as I am concerned. I have no way to quantify this. It broke cleanly, clearly fractured and not at the weld. When it broke it was cutting as nicely as ever. Nor was it a particularly thick cut, about 4 or 5 inches in soaking wet crab apple. The blade was not dull. This is less than the life I got out of cheaper blades, which I always run until they break. I do not recall ever throwing a "dull" blade away.

So my question is am I ahead? Is that the life I should expect, am I doing something wrong that I shortened the blade's life or is it the case that the better cut and utility is what I was paying for and I need to decide if that is worth the difference?

Thank you for responses.

[Bob Bouis]

14" wheels are too small and will eventually destroy any blade from metal fatigue, bigger/thicker ones faster than smaller ones. That being said, the blade makers usually spec a much higher tension than you'd get from the "flutter method." Honestly, there's no substitute for a tension gauge. There's a guy on ebay that sells nicely machined aluminum ones (sans dial indicator) for ~$100. Does that give you a longer life? Maybe. I haven't had one long enough to know for sure.

[Dan Forman]

I use that same blade in a 14" saw, used mostly for green wood, bark and all. No problem with breakage, stays sharp longer than carbon blades. Bi-metal blades are supposed to be tensioned higher than carbon, perhaps that is the problem. If you are just using the flutter method, you are probably not getting enough tension.

When you say the tension guide on your saw doesn't work, do mean doesn't work at all, or is not accurate? Perhaps a call to Laguna would b in order. see what guidance they can give you.

Here is a youtube video on bandsaw setup that a lot of people here like, featuring a guy representing Carter products for bandsaws. Five minutes in he talks about how to set blade tension without a gauge. This would be a good place to start, but then add a little more because it's bimetal. Remember too that the thickness of that blade is .035, which is thicker than a normal 1/2" blade, so requires more tension.

'Band Saw Clinic with Alex Snodgrass - YouTube (https://www.youtube.com/watch?v=wGbZqWac0jU)

I dont think I've heard any other complaints about the Diemaster 2, lots of folks swear by them (not at them :) )

Dan

[Bob Bouis]

I can't find a direct link to it, but the Lenox bandsaw blade sizing guide apparently looks something like this. Obviously it's overly conservative but it's what the maker says.







WHEEL DIAMETER
RECOMMENDED
BLADE THICKNESS


4-6 inches
6-8 inches
8-11 inches
11-18 inches
18-24 inches
24-30 inches
30 inches and over
.014"
.018"
.020"
.025"
.032"
.035"
.042", .050", .063"

[Reed Gray]

Look to see if there are any other fractures in the blade. Most of the time they will be on the back side of the blade. You may need a good light and bend the blade a bit, but some times you can just feel them. If so, then there can be a couple of reasons for it failing like this. Most common one is if do not have the thrust bearings (ones on the back side of the blade) lined up properly so the blade flexes front to back as you cut. This type of break also comes from having the top bearings too high above the cut. If you are cutting 6 inches high, you want the top bearings at no more than about 7 inches high. This also makes the blade flex front to back too much which is what causes that type of crack. If the blade was wiggling front to back just before the break, then that is also a sign that the blade is going. Lennox does have a guide of some sort, paper issue, that I got a long time ago talking about things that make the blade go bad.

That set up clip from Carter is excellent.

robo hippy

[david privett]

there was a video on making a tension gauge on you tube, I made one and it was not bad to make all you need is a few small bolts wing nuts and a dial indicator and some scrap hardwood, I think I used maple. There was something like .001 of a inch stretched tension equals 5000 psi. (Not sure I remember that right) different blade widths change the psi value.

[John K Jordan]

Yikes, I can say in 15 years of using a 14" saw with a riser block and now an 18" saw I have not ONCE broken a blade. I also mostly cut turning stock, soaking wet logs or hard, dead dry wood, up to 12" thick. The blades have always worn out and I sharpen each several times by hand before I toss it and mount a new one. I've used both cheap and expensive blades, almost always 1/2" 3-tpi. Could your tension be TOO high? Something is apparently stressing the blade. The smaller diameter wheels are hard on blades but again, I went through a bunch of blades on my 14" Delta without breaking one.

I too would examine closely for stress cracks - metal almost always fails at tiny cracks. Unfortunately, such cracks are often invisible until the metal suddenly separates. As a former inspector for nuclear piping and structural components I can tell you of a simple method we used to detect surface cracks on certain things - dye penetrant. Sometimes called red check or spot check it consists of three things - a cleaner, a red dye applied to the surface then wiped away, and a white power in a spray can that goes on dry. Any invisible cracks will soak up the dye which then bleeds out into the white powder layer - instantly highlighted. I don't know where to get this cheaply these days (I've had the same cans for decades). It would certainly show stress cracks in a bandsaw blade.

You might ask around and see if someone local has a tension gauge you could borrow, just once, to check your tensioning technique. If you lived near here I'd come over and do it - I have 5 bandsaws including a Woodmizer so buying a tension gauge made sense to me. (I have a Starrett) Except for using it to check my tensioning method for each saw or for a new kind of blade the gauge stays in the drawer but without it I'd never be sure and I hate that.

Since you have broken more than one blade, it might be time to break down and at least use the digital caliper method and a calculator to check the tension - just one time as a sanity check. I have the method saved in my notes if you want it.

JKJ

[Brian Deakin]

I have this odd thought for long time, my son has a guitar headstock tuner would it be possible to use it to set the tension of a bandsaw blade

https://www.amazon.com/Crafter-TG200H-Headstock-Tuner/dp/B002TQ9G7G/ref=sr_1_1?ie=UTF8&qid=1503911931&sr=8-1&keywords=crafter+tuner

[Curt Harms]

Soaking wet? Have you considered a band made for that purpose? Here's one, I'm sure there are others. I think the key is low tooth count and lots of set.

http://www.highlandwoodworking.com/woodturners-bandsawblade.aspx

[John K Jordan]

I have this odd thought for long time, my son has a guitar headstock tuner would it be possible to use it to set the tension of a bandsaw blade


I found this but I didn't check the math: http://www.instructables.com/id/Adjust-Bandsaw-Tension-With-a-Guitar-Tuner/

If it is reasonable, I would still want to use a tension gauge the first time to check.

JKJ

[Dennis Ford]

I too use my band saw almost exclusively for cutting up turning blanks. I am not musical at all and don't have a tension gauge. I do not release the tension until the blade is dull and needs replacing. I tried the Diemaster II blades and really like them but am currently using less expensive Lennox carbon steel blades because I have cut through too many nails (and misc hardware) to risk the more expensive blades.
I suspect that 14" wheels are marginally too small for the 0.032" thick Diemaster II blades and your breakage was caused by fatigue. Possibly the "flutter" of your blades added to the fatigue caused by bending around the wheels.

[terry mccammon]

All:

Thanks for all the good input. I need to quit being so lazy and actually measure the tension. It is not a big deal to do. I am lazy. I very strongly suspect that I am over tensioning, as I do the flutter thing and then crank on the tension wheel, a lot. If a little is good more is better, right? Plus I too question if the saw can even properly tension a 0.5" wide blade. As to tension scale being broken, I mean that the indicator pointer has slipped down and does not move. Yes I need to call Laguna and get that resolved. It happened once before and they walked me through the put it back procedure. That said, when it was working, the indication for a given blade was clearly really light. I also just realized that the DiMaster was a .35 thickness and I absolutely agree that this is too thick for my saw.

So what I did just do was buy a couple of lenox, flexible back, 0.5", 3 tpi, hook that with shipping are just under half the price of the DiMaster. I am going to bother to measure. I am not sure about this but I am under the impression that the tension gauges sold for the purpose are meant to be used with the specific blade they are sold for. I will do the jig thing and be done.

I want to say that I appreciate the assistance and advice. Best regards to all.

[terry mccammon]

I actually purchased one of these and had about the same results. I am buying more or less the same thing for about half the cost.