Bandsaw blade question.......

Discussion in 'Woodturning Discussion Forum' started by odie, Dec 10, 2012.

  1. Ron Rutter

    Ron Rutter

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    Odie. Your main problem is probably being to aggressive with a dull blade. If you do mainly dry wood, blades take a beating. A quick touch on the back of a blade will take out any imperfection at the weld. If you hear a blade ticking it is going to soon break.
    Do you ever tune up the saw? Adjust the guides & bearings. Set the tension correct.
    Too aggressive a blade can be a problem just like on a radial arm saw but slowing down usually solves that problem. Cheers. Ron.
     
  2. MichaelMouse

    MichaelMouse

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    Couple thoughts. WD40 and a paper towel. Turn off the saw, rotate the blade backward through a dampened area if you oil the blade before use. Always do it after use. Wet wood makes corrosion, corrosion dulls a blade. While you're at it, wipe down the iron, too. Especially after nasty, acid woods like oak. Water Displacement, right? Doesn't get oil where it's not needed, and cheaper than aerosol.

    Set in the teeth is a good thing when cutting wet wood. Wood heats and swells, and can grab in the kerf on its own, or with tilt help if you're trying to hand-hold on a less-than-flat surface.

    I won't accept a bad weld. If it's mail order, RMA. A misaligned weld is a sign of carelessness that can also mean an incomplete one. I don't like blades to break.
     
  3. odie

    odie

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    MM......

    Bad welds.......you would be surprised how many blades I've had over the years that wobbled because of a misaligned blade while it was being welded. It's such a simple thing to get right.......I guess some people just don't care about the quality they produce.....

    ......Ho, ho......it's off to work I go!.......:D

    ooc
     
  4. john lucas

    john lucas

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    Odie My blades come from a local supplier who builds them for me for $6 each. They are 1/2" 3TPI and I guess I'll call them alternate set since every other tooth is set opposite. I have had great luck with these and when they get dull I just toss them for that price. They do occasionally have a weld that ticks but that's never stopped them from working just fine. I tried rounding the back of the blades. I can't tell it makes any difference. Maybe it has to do with the set of the teeth. A fairly large kerf may negate any affect dressing the rear of the blade has.
     
  5. dbonertz

    dbonertz

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    Does the size of band saw have anything to do with how long the blade will last. I am looking to purchase a new band saw and was recently told that a 14" saw will go through blades faster than say a 21" saw - assuming all is equal in what is being sawed. The argument was the tighter radius around the upper and lower wheels put more tension on the blades thus more wear quickly. Also smaller band saws typically run on a slower FRPM (foot rotation per minute) than larger saws (2 speed 1700 to 3600 on small saws) and (4600 on larger saws). Any thoughts or comments on this information that was given to me.

    Thanks,

    Dale
     
  6. Greg Thomas

    Greg Thomas

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    blade sharpening

    Odie, I gave you the wrong Raffan book. The sharpening tip is in Bowl Turning on page 39.
     
  7. Edward Weber

    Edward Weber

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    Odie, I'm not going to recommend a particular brand of blade, but a alternate tooth raker design would be better for your cutting habits. This design is not quite as aggressive as the positive hook or claw type but usually will result in a cleaner cut. The reason you are having the blade catch in the blank is most likely a dull blade.
    What happens is this, the point of the tooth enters the wood and tries to pull itself through the blank, but if the gullet of the tooth is dull it can't take that big of a bite and either stalls the machine or throws the blade. This is common with low tooth count blades as they become dull and the problem becomes compounded especially on underpowered machines.
    You might want to stay away from 3 tpi blades and slow the feed rate, don't let the blade pull the wood into it.
     
  8. Wayne Spence

    Wayne Spence

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    Bandsaw blade sharpening

    Odie There are some threads on this subject ,look them up. Rob Wallace has a method I have used for about two years now and can get two sharpenings per blade. You probably know this but on cutting wet wood in particular make sure the piece you are cutting has no movement when passing through the blade. Either have it on a piece on plywood or a flat surface on the wood to eliminate movement.

    I got a piece of exotic wood from a woodcraft store this summer. Unnamed it is the hardest wood I have ever encountered. Couldn't do a straight cut without burning.
     
  9. DOCworks

    DOCworks

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    Odie,
    I use an online company www.carbide.com you can order by specifications. I have a 16" bandsaw and the local stores don't carry that size. They use Lenox blades in carbon steel, bi-metal and carbide tipped. I use the carbon steel, the price is good they are easy to sharpen, although when I mess one up or it gets dull, they usually get cut up and forged into carving blades. I don't know what size saw you have but a 3/8 by 93 1/4 inch blade (14" band saw) with lenox set or alternate set is $12.84 plus shipping. I've been very happy with them.
     
  10. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Dale, if the blade wears out from being dulled then they last approximately the same length of time whether on a large or small saw. However, the blade can also fail from fatigue caused by alternately wrapping around the wheel radius and going back straight several times per second. And, no, a smaller size wheel does not cause higher blade tension. Generally speaking larger bandsaws are set up to have slightly higher tension because of increased likelihood of flutter due to the longer distance from wheel to guide. The other thing that is the main cause of higher dynamic tension in larger bandsaws is the speed of the blade. Large saws generally run at about 3500 to 4000 FPM while smaller 14 inch saws run at about 2400 to 2700 FPM. Bench top bandsaws run even slower. Avoid getting a three wheeler as they are likely to cause a blade to break from work hardening fatigue well before the teeth get dull.

    Also, after about five years it would not hurt to check the tires occasionally. A rubber tire reacts with ozone a becomes hard and brittle. Under bright light you can see small hairline cracks that run from side to side and the tire may also appear glazed. A worn out will slightly flatten the set of the teeth on one side of the blade. I don't know what sort of useful life the urethane tires have.
     
  11. robo hippy

    robo hippy

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    In the battle between carbon steel and bimetal, it is like the battle between standard matrix grinding wheels and CBN grinding wheels. A bit more spendy, but a way better value considering change out time and how long they cut. Carbide blades are for cutting veneers, and not really for resawing. Almost no set to the teeth. I know, I tried one out.

    robo hippy
     
  12. odie

    odie

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    Thanks for this information, Bill......

    I believe you are correct that what I need is an alternate set blade, and the trouble I've been experiencing is using a blade designed primarily for KD wood (positive claw), when much of the wood I cut on the bandsaw has a higher MC.

    I'm thinking the alternate set won't be as aggressive as the positive claw when sawing KD wood, but shouldn't have any problems cutting it at a little slower feed rate......therefore, it should be a good blade to cover all the bases!

    I believe I'll order a couple carbon steel 111", 3/8 wide, 3tpi, alternate set blades from the outfit Docworks suggested......carbide.com. At $14.28 each, I'm not going to bother with resharpening them. We'll see, but if one of these blades lasts me 6mo, I'll be satisfied. (I don't throw old bandsaw blades away, so the option of resharpening some of these is available to me somewhere down the road at a later time.......)

    I also looked over the rules for blade tensioning......that will help me to get the tension correct.....thanks.

    Note to Robo Hippy: I might have gone for the bi-metal, but it wasn't available in the configuration I'm interested in. The bi-metal appears to be about double the cost of the carbon steel.......not sure how that would have effected the purchase, but it would have been part of the equation.

    ooc
     
    Last edited: Dec 11, 2012
  13. Ron Rutter

    Ron Rutter

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    Odie. An alternate set will turn corners better as well! For those interested I use a 7/32" cylindrical stone meant for sharpening chain saw blades, in my Dremel to sharpen BS blades. There are probably 5/32" available as well.
    A hook tooth will probably cut KD lumber much better than string wet stuff.
     
  14. Richard Jones

    Richard Jones

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    The strike-through is when I put a blade on. The new date is when I put on a new blade. Several hundred green bowl blanks (guessing about 400): walnut, cherry, hackberry, maple, beech, Bradford Pear, sycamore, oak, etc. Plus resawing green and KD. Plus countless box blanks. Plus beaucoup shaker blanks and pepper mill blanks. Hundreds of maple angel blanks. Hundreds of maple light bulb blanks. Even some aluminum. Maybe 200 KD blanks for spin tops. A hundred or so crosses that we sell at the store. A hundred or so cedar vases. I'm sure I'm leaving something out.

    I've been really hard on it this time. It still cut fairly well, but I was having to push a bit to feed, and I value my fingers more than the blade.

    You will be hard pressed convincing me to buy anything other than the Lenox bimetal.

    Rich
     

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  15. Bill Boehme

    Bill Boehme Administrator Staff Member

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    John, the purpose of rounding the back of the blade is primarily for making tight turns where the back of the blade is riding on one side of the kerf. Typical bandsaw blades have a fairly sharp corner at the back and it can hang on the wood and have a tendency to pull the teeth away from the cut. When the back of the blade is rounded and polished this tendency is reduced considerably. You can tell if this is happening by examining the kerf on tight radius cuts. If you see vertical ridges with light burn marks, that is most likely from the back edge of the blade cutting a tiny groove and hanging.
     
  16. MichaelMouse

    MichaelMouse

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    Bill's close with the smaller wheel controversy. The phenomenon is known as "work hardening," and is like cold-working metal with rollers or hammering. It make them harder, which, as usual, makes them more brittle. Cracks develop at the bottom of the gullets where the stress from the tooth hitting work meets the main blade. They can spread to failure.

    Don't believe tension is a player except that it might complete the work stress started when increased.
     
  17. john lucas

    john lucas

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    Well this is extremely unscientific but I started with a 3 wheel Delta bandsaw. It sucked by the way but it wasn't because of blade breakage. I bought it for resawing and general bandsaw work and then eventually tried to use it for green bowl cutting. The blade wandered everywhere. I don't ever remember breaking a blade. I bent a few and ruined them that way.
    I stepped up to a 14" saw. Off brand at first and then a Delta that I own now. I do break a blade occasionally but they are cheap blades welded up buy my local saw sharpening guy. I don't think I break any more than my closest friend who has a 20" bandsaw. He buys his blades from my same guy. We've discussed blade breakage which is really pretty infrequent for both of us and he turns at least as much as I do. We both use our saws for Resawing and other chores as well.
    For recreational use such as most of us put our saws through I'm not sure the wheel radius is a factor in blade breakage but like I said this is just an opinion based on owning and working with other saws.
     
  18. robo hippy

    robo hippy

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    Odie,
    Like Richard said, you really get so much more with the bimetal blades.

    The main problem I have had with blade breakage is from not lowering the upper blade guide down to the work level, and maybe from feeding faster than I should. I have lost several blades to cracks forming on the back of the blade. Think of pushing on a stick. It will bow away from the pressure. This puts stress on the back of the blade. Usually if there is one crack, there are many. Time to scrap it. If you are running your blade, and it is moving front to back, this is why.

    Oh, yea, the dull tool saga: when it gets dull, sharpen or throw it away. I have a couple of knuckle scars from making 'one last cut'. Learned that one by peeing on the electric fence. Never again. Lucky it was only a flesh wound.

    robo hippy
     
  19. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Sounds like what Lil Abner's Fearless Fosdick used to say.

    There is a downside to having a bandsaw with a really big motor. I have a 16" Minimax with a 3.5 HP motor and had just installed a new 1" blade to cut some mesquite into turning blanks. As I recall, I was a bit careless and put a large piece on the table that was slightly rounded on the down facing side. Of course, it rolled and since the block was about a foot thick, the blade stuck and the next thing that I remember was something that sounded like a rifle shot as that new one-inch blade snapped. After a trip to change clothes, I examined the blade and saw that there was no point in re-welding it because it had likely exceeded the elastic limit in tension and was necked down slightly near the break. The break was not at the weld.

    John, small thin blades are fine on a three wheel bandsaw. It is the wider and thicker blades that are likely to fail.
     
  20. john lucas

    john lucas

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    Bill Yes, and the wider thicker blades could not be tensioned enough to cut any straighter than the narrow blades. I did all my resawing and bowls with a 1/4" blade because the larger blades bowed worse. That saw was a dog for what I wanted to use it for. It was pretty good for just sawing curves in flat work and with the 16" it was pretty handy. Of course it only had about 5" depth of cut.
     

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