Bandsaw Blade Breakage

Hi Erroll My suspicion is first 3/8 wide blades are probably to narrow for what you are sawing, I would also set my back of the blade closer to the guide, like just from not rubbing to just touching, however I doubt that that is the mayor cause of breaking, pushing and twisting a to narrow blade is what I would suspect as the mayor reason. Do you have blades with a extra wide set, assuming you are sawing wet wood also, because a wider set blade would have less friction and heat build up and the kerf being wider would also help in less twisting of the blade when maneuvering the wood around. Just my look at it, there might be some other thought on this.

Have fun and take care Leo Van Der Loo

Errol, I have the same saw. I use it for resawing, and cutting out bowl blanks. I do the radius cuts on my smaller saw with a 1/2 inch blade. On the Laguna, I have been running an 1 1/4 blade. I did have one that broke, but it didn't break on the weld. I keep the tension up high. I agree that the 3/8 blade may be too light duty for the saw, and there are several thicknesses of blades available. I wouldn't attempt to cut

16 inches high with that small of a blade. robo hippy

Of course, 3/8 is _not_ to small for the saw, and it's absolutely necessary for smaller work anyway, so I wouldn't worry much about that. Apply appropriate tension and it will do fine.

On the subject of tension, too loose can be as bad as too tight at breaking welds. The blade might be compressing as it decelerates into the wood , putting bending stress on the weld. I go with the manufacturer on tension suggestions, but a little more is better than a little less. Make sure the blade's supported close to the top of the piece.

Now on to feed rate and thrust bearings. You set them close, and feed at a rate that barely deflects the blade in to them? Low tension can be your enemy here, as well. Think Duginskie calls it "beam strength" in his excellent book. Here's where wider blades make a difference - feed rate.

Closely related to feed rate is feed stability. If you don't have the blank stable and supported below, it can wobble on you. This puts stress on the blade, of which the weld is still the weakest part, the same way low tension and high friction can. Get a flat surface to bear against with your scrub and block planes. A circle-cutting jig is great insurance as well, assuring that side loads are minimized. Make one, try it, and you'll see how it makes what they told you about sawing - you have to feed as you turn, not feed then turn - a cinch.

There's also a difference in blades beyond TPI, where yours sound fine for small rough work and 6" blank cutting. I prefer set to skip in the teeth, especially for wet woods. Keeps the blade from binding by making a wider kerf. Your 3/8 will bind less than a wider blade at the rear, and binding is what exacerbates low tension problems and heats the band, so you're probably in a tradeoff there.

One last thing that is perhaps just a fetish at my house is corrosion. If I'm cutting acid woods I always try and back the blade up manually through a WD40-soaked paper towel to clean it. The pits that acid can form not only ruin the sharpness, which of course means it feeds harder which means you have to push harder and the blade binds in the cut and ... it eats the weld as well. Maybe even more, because the area is rough from being ground flush anyway. At the least, you'll get some more good cuts by keeping the blade clean, so I figure it's worth it.

Errol, looks like you have some good advice from others but i would like to add some thoughts. Blades do break! How much usage are you getting from a blade?

3 different sources of blades doesn't tell us if it was 3 different manufacturers. I am not familiar with your saw so have to ask is the motor Laguna supplied or was it bought separately. If not a Laguna motor is it the right speed (RPM). Before you install a new blade run your fingers over the weld and check for any roughness or bumps. Remove with a Dremel or a slip stone before installing. Try changing the ceramic guides with cool blocks. Make sure the guides are set behind the tooth gullet when the blade is at maximum deflection. Use Pam as a lubricant when the blade is in the wood. Lastly get Mark Duginske's book.

Peter, I am curious as to why you would recomend the cool blocks over the ceramic blade guides. They both run cool, and I would think that the creamic would outlast the cool blocks. robo hippy

Thanks for the replies. I will try to add more tension and see if that makes a difference.

I am not familiar with any of the brands you mention except Starret We use these at work on a 20" General and they take all sorts of abuse and never break. This saw is used by 10 different people of varying skill levels and none of them even think of changing a blade or even matching a blade to the sort of work they are doing. Materials cut range from aluminum to plexiglass, plywood, maple and pine. Sometimes the harder guides like ceramic tend to case harden the blade especially if there is unevenness in the weld or they are set too close. As the case hardening occurs it causes the area around the weld to become brittle and the constant bending around the wheels causes failure. 3 wheel machines also tend to break welds because of the smaller radii of the wheels. If you take a coarse sharpening stone and gently round the back edge of the blade with the saw running it helps when cutting tight radii. Lee Valley sells a special stone for this. I think the low tension is a factor and you should always bring the top guides down to be almost in contact with the wood. Also do not forget to correctly adjust the bottom guides when you change blades. Don't laugh I see it all the time! Good luck!

See my second posting to Errol. I have a Rockwell 14" BS and tried ceramic and roller bearing guides and noticed more broken blades. Went back to cool blocks and no breakages. Also I now recycle the Starret blades from work. I cut and silver solder them to fit my Rockwell and then sharpen with a high speed rotary tool. Good enough for blank cutting and general work. I also tuned the BS with Mark Duginske's help and can re-saw veneers with a freshly sharpened recycled 1/2"blade.

The ceramics are so frictionless that there isn't a chance to build heat. Unless someone's been roughening yours, and it'll take some real abrasive, not going to be the problem.

Not to mention, they don't wear as the blade tries to wander out from the center of the circle you're cutting. Wear on softer cool blocks in these circumstances can allow twisting of the blade, with premature consequences of breakage.

In Errol's original posting he mentioned a tick tick tick sound from the blade before it broke. This suggests to me that the welds were rough and in fact the ceramics are behaving like hammers and that sets up a hardening effect that makes the weld more brittle and it breaks. I would not personally go back to ceramics. I had breakages when I used them and really don't know why. So I went back to cool blocks because they worked better for me. The General at work has mild steel guides that get really badly scored but the blades don't break they get retired!

I talked to my bandsaw blade maker, and asked him about the breaking of my blade. He said to make sure the thrust guides were set properly, perfectly in line with the blade, and to make sure that you had the top guides down close to the wood. If either or both of these conditions exist, it will put stresses on the blade that can cause it to break.

When my blade broke, it was also making a ticking sound, but I figured that was because the 1 1/4 inch blade was moving about 1/4 inch foreward each time the blade came around to the broken spot. He found several other breaks in the blade, so it was trashed. The ticking sound only started when the blade began to break. There is no sound when it runs now. robo hippy

So breakage obviously has nothing to do with guide heat buildup, as the steel guides are the worst offenders in that department. Not to mention the wood itself!

He did say that he paid strict attention to only one of the setup criteria, that of clearance on the guides. It's the low tension and poor support that's getting him.