15

I have an older Craftsman band saw that is very difficult to get the blade back in place and it tends to toss the blade often. It makes it annoying to use the tool. I'm wondering if there is a common set of causes for this behavior that I might be able to use as a diagnostic checklist.

  • When that happens to me, it's generally because the wheels are tipped to one side or the other. To check that they're centered, I run the blade through by hand to make sure they stay in the center. Have you tried that? Generally there's an adjustment that can be made that tips the wheels one way or the other. – dfife Mar 17 '15 at 15:47
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    Sometimes even the tension can cause this problem. – BrownRedHawk Mar 17 '15 at 15:54
  • Would too much tension cause this too? I try to make the blades pretty tight with 3/8" blades and less tight with the 1/8" blade. – Peter Grace Mar 17 '15 at 16:02
  • Are you adjusting your thrust bearings correctly? They should barely touch the band when you spin the wheels by hand, with the blade centered on both tire crowns. Also... are the bearings for your upper wheel tight and in good condition? If they've gotten loose, the upper wheel can wobble and toss the blade. – TDHofstetter Sep 7 '15 at 3:36
15

Your saw may be poorly adjusted.

A properly tuned band-saw has the wheel axles exactly parallel and the wheels in the same plane. The axles can be adjusted using the tilt screw on the upper wheel.

If that doesn't help than it may be the crown of the wheels is too flat. Put a ruler on the wheel and see if there is enough of a crown left. If not then you will need to replace the tire or wheel.

http://woodgears.ca/bandsaw/bandsaw_crown.jpg
image source

  • Actually, no, if the wheels are perfectly parallel / coplanar, then they're not set properly. You want the wheels in slight opposition to each other- that 'holds' the blade in place. – TX Turner Apr 16 '15 at 14:24
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    @TX Turner, I think they're designed so the crown will keep the blade tracking correctly. The wheels should be coplanar. – lars Apr 16 '15 at 16:38
  • Talk to a band saw manufacturer. If they're coplanar, pressure from cutting a material will push the blade off (because there's no resistance to side to side movement other than tension.) Tracking works by controlling the amount of non-coplanarness (non-coplanarity?) Basically you've got two wheels that form the front edge (top wheel) and the back edge (bottom wheel) of a V groove. Any lateral force (from say cutting something and pushing against the blade) is counteracted by the blade 'climbing' the 'V'. – TX Turner Apr 16 '15 at 17:06
  • youtube.com/watch?v=wGbZqWac0jU 6:30 or so in. – TX Turner Apr 16 '15 at 17:11
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    @TXTurner You check the article the image in the post comes from. or check this video – ratchet freak Apr 16 '15 at 17:40
3

Not in any particular order:

  1. Not enough blade tension
  2. Blade alignment incorrect - adjust the wheel angle with the provided knob. The teeth gullets should be in the center of the tire of the adjusting wheel.
  3. Blade thrust guide not adjusted properly allowing the blade to be pushed off the wheel. Less than 1/16".
  4. Very worn tires
2

A dull bandsaw blade will tend to move to the side as well. I've never had it move to the point of falling off but that may be something to look at too.

0

Recently had the problem of the blade sipping off and taking the tire with it' Finally found the set screw on the drive wheel loose and the wheels out of alignment.

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