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  1. #21
    Geia sou, Vageli.

    I found this thread after googling for 1605 runout. I happen to have 3 lengths of 750~800mm 1605s that show up to 1.3mm (!) of runout.

    I put them on v-blocks and tried to apply force in the middle. I can bend them both by hand or by using a clamp (with a v groove on its plastic end). However, no matter how long I hold this position once I release them they spring back to their original shape.

    I am leaving the clamp on one overnight to see if this helps. I am pushing down 0.8m (i.e. 0.15mm further down from the middle 0.65mm position).

    I was wondering what did you eventually do with yours.

    Cheer,
    Elias

  2. #22
    After finding this topic, I thought to give it a go.

    As numerous people with Chinese rolled 1605-C7 ballscrews, I have to somehow deal with bends ...or live with them. In my case, we are talking about 3 items of 720~780mm lengths and 0.54~1.32mm runout (the latter can be seen with naked eye). This is how I am trying to deal with it.

    Click image for larger version. 

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    After finding the high spot, I have tried several variations:
    - v blocks at ends, quarters, 100mm and 50mm from high spot
    - bending down by 0.5*runout, 0.6*runout, 1*runout, 2*runout
    - applying force for 1m, 2m, 10m, 1h, 10h

    Of course I have not tried all the combinations of the above and I have lost track of what combinations I have actually tried so far. I am trying to deal with the worse runout of 1.32mm and after a couple of days I am down to 1.21mm. I would not call this a progress.

    Therefore my question to people that have had (some) success in the past is whether they remember what recipe (v block spacing, amount of bend, time of bend) started showing results.

  3. #23
    I think you just need to bend them further, to not spring back. You are probably not applying enough stress to go past the material's elastic limit.
    Old router build log here. New router build log here. Lathe build log here.
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  4. #24
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 3 Hours Ago Has been a member for 9-10 years. Has a total post count of 1,791. Received thanks 189 times, giving thanks to others 5 times.
    Quote Originally Posted by Jonathan View Post
    I think you just need to bend them further, to not spring back. You are probably not applying enough stress to go past the material's elastic limit.
    This.
    If you don't bend past the elastic limit, then they will just spring back, regardless of how long you leave the clamp on. Position of support blocks, and pressure application point depends on the bend. How much pressure is very much trial and error. Apply pressure, release pressure, check to see how much things spring back, then repeat with more pressure if needed.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  5. #25
    Quote Originally Posted by auhopu View Post
    I put them on v-blocks and tried to apply force in the middle.
    For straightening you ideally need to apply a precise displacement then measure to see if you have achieved a permanent change, then keep increasing the displacement applied until you get the required change.
    Measuring force is an imprecise way of straightening things, a press with a dial gauge is your friend ;-)

    - Nick
    You think that's too expensive? You're not a Model Engineer are you? :D

  6. #26
    This video has some insight on how it is done:

    www.emvioeng.com
    Machine tools and 3D printing supplies. Expanding constantly.

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