Idea: Carbon fiber rods for gantry

Discussion in 'Guides, Mods, and Upgrades' started by mhe, Jan 1, 2018.

  1. mhe

    mhe Well-Known Member

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    Hi folks, just stumbled across a vid of somebody testing ripple and backlash with different kinds of rods for the gantry at the same accelerations. Reducing moving mass on the gantry should lead to more precision and less backlash.



    Has anyone of you tried this on a Bigbox? How strong would a carbon rod need to be for this to be a good thing? How about abrasion done to it by the bearings, would it work with IGUS self lubricating bushings?
     
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  2. JvdP

    JvdP Well-Known Member

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    I've seen his videos before and I really like the idea. BigBox has a really, really heavy Y-gantry and thus you need to keep printing speeds low. In addition to this, on the dual it has a whopping 3 stepper motors on the Y-axis, even more on IDEX configurations. How can we reduce this weight?

    If you want to know more about the carbon fiber X-axis tubes, including updates on abrasion, he has more videos.

    More detailed info on Carbon Fiber Tubes:


    Update regarding Abrasion:


    In case you're still worried about abrasion, it might be of comfort that the tubes are very inexpensive. If only the X-axis was easy to swap...
     
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  3. mhe

    mhe Well-Known Member

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    I already saw that the rods are pretty damn cheap, way cheaper than the steel rods. How about sagging? I am in the process of an IDEX conversion, might as well do that with carbon rods to get the weight down as much as I can. The conversion from the 1.0 dual with the heavy extruder steppers to titans should already shave off almost a full kilogram from the Y axis. I'll give it a shot, my steel rods won't go anywhere in case I want to go back, so why not!
     
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  4. eca

    eca Well-Known Member

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    Any news about this? Would we need to use 10mm CF tubes, or would 8mm also work so we don't have to swap over half of the gantry?
     
  5. eca

    eca Well-Known Member

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    After reading some, I decided to go ahead and order some 8mm carbon fiber pultrusion rods, not tubes. They are supposed to be stiffer to bend than the woven CF tubes of the same diameter. Also, they would be hopefully a direct swap with the steel rods that I have in now.
    I can't just leave the printer alone...
    At least if it doesn't make a difference I won't be printing out a whole new gantry.
     
  6. JvdP

    JvdP Well-Known Member

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    What's the weight difference between rods and tubes? 8mm sounds a little thin but maybe 8mm rods are just as stiff (or stiffer) than 10mm tubes.

    What bearings are you considering?
     
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  7. eca

    eca Well-Known Member

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    Yeah, the talk about tubes being stronger than rods is true when they weigh the same amount. Otherwise, the rods are stronger, 10mm rods would be stiffer than a 10mm tube.
    I have Igus on my machine right now and would try them on this as well.
    I received them yesterday and they are exactly 8mm. I need to polish them a little (didn't notice that they were "partially finished"), so there are little carbon fiber strands all over the surface. Just checking how the Igus bearing slid on it (which was smooth) created little showers of carbon fiber dust to come off. But after polishing the loose fibers off it will be fine.
     
  8. eca

    eca Well-Known Member

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    Not sure the weight difference, but the 500mm rods are supposed to be about 40 grams. And the pultruted CF is supposed to be stiffer than weaved CF.
     
  9. moshen

    moshen Well-Known Member

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    I was thinking of doing this, let me know how it turns out!
     
  10. eca

    eca Well-Known Member

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    Sorry, I am on vacation and won't be able to finish this for another two weeks. But I will post here when I am finished.
     
  11. Thomas.

    Thomas. New Member

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    I should have posted about this months ago, I have already tried swapping my rods with CF tubes.
    Yes, sagging is a massive problem, the bigbox has relatively long axis rods and when the both carriages were in the center I saw almost 4mm of sagging. I did that testing with the super heavy OG dual hybrid carriage, so it might work out better with some of the new lighter designs.

    Also, if you're trying to get the tubes sourced from china, you are going to have trouble with sizing. Almost all of the "8mm" rods I bought were closer to 7.8mm and had tons of slop using the normal bearings
     
  12. MyMakibox

    MyMakibox Well-Known Member

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    I'm going to give this a go too. I have some 50mm-lomg 8mm rods which seem to be a consistent diameter, but with a slightly rough surface. I'll try polishing them to reduce friction.

    Are bearings usable with carbon fiber rods? Wouldn't the steel wear down the rods? I've printed a bunch of bushings in PLA as an alternative.
     

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