Loosening blades when not in use

daveinjerseyApril 15, 2011

My dad always said I should loosen coping/hacksaw blades after use. Never seen this recommendation elsewhere. Anybody else do this/heard of it?

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Heard itm seldom do it. Even with bandsaw blades. But, I use Timberwolf bandsaw blades which are tensioned by the flutter methoid and are not under a lot of tension in the first place.

I think the point is to relieve the tension in the metal when not being used. That might have been a good thing years ago when steel was of lesser quality and teeth treatments could actually weaken a metal blade.

Not so much any more. I think I have broken two bandsaw blades in 10 years. And those were 1/8" or 1/4" sizes.

    Bookmark   April 16, 2011 at 10:56AM
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Bandsaw blades need to be loosened to prevent compression of the tires on the wheels.

It the tires get a compression set the blade tension will vary as the wheel rotates and cause poor cutting and wander.

Hacksaws and coping saws are fine either way since they are normally all metal affairs anyway.

    Bookmark   April 16, 2011 at 11:25AM
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Thanks to both.

    Bookmark   April 16, 2011 at 11:37AM
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I must not be using my bandsaw eouugh. I went to the manufacturers website and found this:

When you are done cutting for the day, take the tension off your blade. Band saw blades, when warmed up from cutting, always stretch; and upon cooling shrink by tens of thousandths of an inch each cooling period. Therefore, blades, when left on the saw over tension themselves and leave the memory of the two wheels in the steel of the band, which will cause cracking in the gullet. When you leave the band on your saw under tension, not only do you distort the crown and flatten out the tires (which makes them very hard), but you also place undue stress on your bearings and shafts. Believe it or not; you can, and will damage your wheel geometry sooner or later and considerably shorten bearing life. You are also crushing your tires or V-belts."

I bought new tires for my saw from them. The blades have been on the saw for over 8 years---never having been detensioned except for changing blades. And then retensioned using their recommended flutter technique.


    Bookmark   April 16, 2011 at 7:09PM
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The thermal expansion of steel is 6.45e-6 inch/(inch-F)

A 111 inch bandsaw blade expands 0.000716 inches/F.

Not a significant an mount compared to the compression available in the tire.

    Bookmark   April 17, 2011 at 9:43AM
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You really don't want your band saw wheels failing explosively, so this is probably excellent advice, and potentially lifesaving. I'm going to the basement now to loosen mine, which has been under constant tension for 25 years. Ugh.

    Bookmark   April 17, 2011 at 12:29PM
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Yeah, me, too, neither.

I have read for years of the detensioning advice. In fact, there are several detensioner attachments to more easily do that. Instead of loosening the adjusting wheel and vounting the turns.

I bought tires and blades from Suffolk---no detensioning and no problems.

    Bookmark   April 18, 2011 at 11:11AM
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