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Thread: Why release the tension?

  1. #61
    Join Date
    Dec 2008
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    Northern Michigan
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    Never! No problems.

    Did you ever buy that Lamello thingy? Bought my ex out of my house instead but is still on my radar when the $$ balance is back up.

  2. #62
    For years I worked for a family run mill work business....not my family. Some of them were detensioners and some were fogetabouters.
    All I can tell you is they never broke the machine.

  3. #63
    Join Date
    Feb 2016
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    NE Iowa
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    Yep. For a time I thought I'd be good and detension when done with the saw. All it ever accomplished was to cause me trouble when I next needed the saw and forgot - despite all the clues I left myself - to retension. I quit after a couple of those episodes, and ten years on the same saw have never seen any ill effect from leaving tension on.

  4. #64
    Join Date
    Jan 2008
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    Western Nebraska
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    4,680
    Quote Originally Posted by Larry Edgerton View Post
    Never! No problems.

    Did you ever buy that Lamello thingy? Bought my ex out of my house instead but is still on my radar when the $$ balance is back up.
    I didn't yet, I was hoping you'd buy it first and give it a good test so I'd know if it was a good idea! Sounds like you are probably spending wisely though. Was actually just thinking about it yesterday. It would make this current job easier to install, ought to just do it. I really don't like the domino, lamello might be the better mousetrap.

  5. #65
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    Oct 2007
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    I have two bandsaws. The 20 year old craftsman has never had the tension released and seems to yuan fine on the original bearings and tires. The newer rikon is rigged with a micro switch that turns two led task lights on when it’s under tension. That means when I leave the room and turn out the lights, the bandsaw nags me. In truth, I think the Craftsman runs smoother.

  6. #66
    Join Date
    Feb 2003
    Location
    San Antonio, TX
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    530
    Some of the question of detension or not to detension comes down to the saw and the materials used in the critical parts.
    I just replaced the hinge for the upper wheel on my JET JWBS-14CS. This spent probably a decade where I just left it under tension. The upper hinge assembly is made from some cheap pot metal and distorted over time, to where the hinge was interfering with the shroud (I though I had a picture of that from before). This would interfere on adjustment and tensioning.
    old bandsaw hinge rotated.jpg
    This is the original hinge compared to an engineer's square. The hinge arm is bent, so that it interferes with the sheet metal shroud. The part where the arrow is pointing is where it would interfere.

    new bandsaw hinge installed rotated.jpg
    This is the replacement hinge with an iron pivot arm. (item 153303814248 from wmprice on ebay) I tried to email to make sure I got the correct assembly, but no response. Since the dimensions seemed correct I went ahead and ordered.
    The two arrows show where I had to use a file to trim the pot metal back a bit. If you do this have a file card around since the pot metal will clog up the file.

    When I first started to look into repairing this a couple of years ago, I tried emailing with Iturra but had issues with him responding. (I think I got a response to my first email, that my vintage saw could not have that problem, and then no response to my followup email. While by reputation the Iturra parts are probably better, I went with where I could deal with an online order (even though the email responsiveness was about the same))

    John

  7. #67
    Quote Originally Posted by John Stankus View Post
    ... the materials used in the critical parts. ...
    I de-tension a RIKON because it's easy, I don't have to even think about creep in the materials, and I swapped a mechanical for a tension-interlocked mag starter. Now even I can't mess it up.

  8. #68
    Join Date
    Nov 2016
    Location
    Atlanta
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    18
    Quote Originally Posted by John Stankus View Post
    Some of the question of detension or not to detension comes down to the saw and the materials used in the critical parts.
    I agree that this is the key issue.

    Specifically if zinc parts are used as in the example given by John. Zinc alloys are very susceptible to creep. For the technically inclined here is a link to some details:

    https://www.dynacast.com/en/knowledg...als/zinc-creep

    Note in particular some of the graphs are creep rate in % per 10,000 hours which is a little more than a year. So the takeaway for me is a less robustly designed part could be moving quite significantly over the expected lifetime of a machine.

    So in that case detensioning would be a good thing to do to prevent premature failure of the zinc part.

    Of course your mileage may vary.

    Tim Orr

  9. #69
    Join Date
    Apr 2018
    Location
    Cambridge Vermont
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    I don't think you'll see a black and white difference. Most of the "I don't" people seem to not do it because they don't want to take the time to do it or because they will forget to tension it. I'd be in that group except for my Grizzly has a lever so it's quick and a key to turn on the power that gets hung on a magnet next to the lever when detensioned. In the long run I think it's better to remove the tension. It's just not easy to see any results. Most people would never notice if their BS has slightly more vibrations than when new. Most likely the bearings, while could be damaged, will still work just fine. In fact most would feel that if they got 25 years out of a bearing to be good. Yet that same bearing might have gone twice that, you'll never know.

    One thing is for certain. Very little, if anything, is under the same tension as a BS. Belts are the most common thing and the level of tension they see is a tiny fraction of what a BS is set up to.

  10. #70
    Join Date
    Dec 2006
    Location
    Toronto Ontario
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    11,248
    Actually the tension on a bandsaw is very slight.

    I have a 90 year old motorcycle, I never detension the valve springs, they're doing just fine.

    Same for all the springs in dampers, Reeves drives etc.

    I guess if you have a "bandsaw shaped object" as opposed to a bandsaw it could be an issue, however with over 40 years in industry I have never seen a saw detensioned and many are 40 or 50 years old......Regards, Rod.

  11. #71
    I don't think the metallurgy or creep properties of the tensioning springs is in question (same for a motorcycle). It is the other parts of the system that give me pause.

    (A motor's valve spring is much more likely to break due to fatigue imposed by the high cyclic rate of load changes. I'd have to be really quick on the lever of a Rikon to replicate it.)

  12. #72
    Join Date
    Feb 2008
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    E TN, near Knoxville
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    Quote Originally Posted by Malcolm McLeod View Post
    I don't think the metallurgy or creep properties of the tensioning springs is in question (same for a motorcycle). It is the other parts of the system that give me pause.
    (A motor's valve spring is much more likely to break due to fatigue imposed by the high cyclic rate of load changes. I'd have to be really quick on the lever of a Rikon to replicate it.)
    The tension spring was prone to "weaken" in the common older 14" Delta and Jet saws with cast iron frames. This happened to the one in my old Delta after about 10 years. I bought a replacement spring from Iturra and it was a better quality spring.

    Other tensioning parts of the system on the Delta did distort and had to be replaced, but the spring did too.

    I also fixed an old Jet with the same problem that John Stankus mentioned. The cheap metal had deformed. I was asked to stop by the community training organization and adjust the tension of the saw but didn't bring tools. Fortunately they found a file somewhere so I made it work.

    JKJ

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