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Belt Tension Question

Discussion in 'Grinders' started by ToddR, Jan 3, 2017.

  1. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    Hi all. I'm revisiting this question because i've been having more problems with this lately. It's not that it bogs down so much but if i'm really grinding hard on some steel, the belt wants to move on me. Sometimes it "pops" off to one side of the drive wheel's bump even. It's not yet flown right off but it does like to move around. I use a gas shock from a car hatchback for tension but it's only rated at about 30 lbs. Do i need something stronger? Or am I just pushing things too hard. I don't really have a feel for how much tension the belt should be under.
     
  2. John Noon

    John Noon Well-Known Member

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    Every time my belt needs to get some exercise it is because it is to loose and when putting pressure on the belt it becomes very noticeable
     
  3. dancom

    dancom Dust Maker Best Shop Tool

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    30 lb spring has always worked well for me. The gas springs suffer from temperature issues. Is it colder in the shop than usual? My back door on my van won't even stay up at -25 with two gas springs. They suck in the cold.

    I have also noticed some J flex belts want to go wonky when I work them hard on the platen. I think they are not the best belts. Never had an issue with heavier belts.


    Dan
     
  4. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    Ah yes... the cold. Didn't even consider that. I just bought a 4.5" spring that should fit inside the tube. I will put it in place this weekend as I owe my brother a kitchen knife.
    Thanks Dan
     
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  5. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    Hi Dan. I pulled the gas shock out and put the spring in. With the blocks I use with the shock out, I lucked out and needed no other mods. It works well and, for sure, really holds the belt steady. But, I'm worried it's too much tension. I can almost strum the edge of the belt and get a "twang". It seems to work better than ever but am I wrecking belts or worse?
     
  6. dancom

    dancom Dust Maker Best Shop Tool

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    Todd,

    The belt seams are usually made pretty well, but obviously too much tension and belts will be failing prematurely.

    What spring do you have in there? I used a bathroom scale and pressed down on the spring. It took about 30 lbs to compress it inch. You'll be okay with anything up to 40 lbs. I read in a Klingspor guide http://www.skookumtools.com/uploads/Belt_Polishing_Speeds_Metal_and_TS.pdf to determine the tension requirements when making my grinder.

    Hope this helps,

    Dan
     
  7. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    Thanks for that doc. Good info. I thought I had read that it was a 30 something lb. spring. But, that may have been only for an inch of travel. I have to use a lot more force to compress it and I have to move it 2-3" now. I think I need to measure it. I ordered a similar spring with thinner "wire" material and longer. I will cut a section from the middle and use it. Between cutting off the boxed end of the spring and the thinner coils, Im guesstimate I will be in range.
    To be honest, it tracks perfect right now. I just don't want to stretch my scotchbrite belts or put too much load on the motor.

    Thanks again
     

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