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Thread: rails vs rods?

  1. #1

    rails vs rods?

    Hi guys
    firstly, this is my first post here, so Hi, and sorry if I've managed to stick this in the wrong place or its been discussed to death already :/

    so here we go...
    I'm building a coreXY printer. Basically, my current I3 clone isnt up to par with what I want to do... That'll teach me for getting the cheapest printer I could lay my hands on

    Anyway, I'm skimping on the aesthetics (I'm using a flipping Ikea lack table, with added supports, as a frame) so that I can focus on the bits that really matter, and make it a better printer.
    So, I've come across a number of arguments for the use (or not) of linear rails rather than the standard rods. anyone got experience with these? Any thoughts\feeling\advice?

    thanks

    Dan

  2. #2
    Staff Engineer
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    In general, square-section profile rails with bearing trucks will work better than rods and round sleeve bearings. They are more rigid and have less slop. But they need to be mounted to something extremely flat, and they have to be exactly parallel, or they'll jam up. I'm not sure your Ikea table qualifies as a mounting surface; you might find the rods more forgiving.

  3. #3
    Quote Originally Posted by awerby View Post
    I'm not sure your Ikea table qualifies as a mounting surface
    my 5 ikea table (its the cheapest table they make)

    Technically, if assembled correctly, it should be perfectly straight legs parallel ect... but that relies on so much more than just my building ability...

    Youre probably right. Now, I can get the rails perfectly level no problem, but I'd be relying on the table legs being parallel to to keep the rails parallel...
    I was considering getting some 2020 extrusion to make the frame work, but that seems to cost more... but might save me some heart ache in the long run

  4. #4
    Staff Engineer Davo's Avatar
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    If you're going for increased precision, don't cheap out on the frame. 80/20 (assembled with a machinist's square) and linear bearings are the way to go (from the options you've listed).

  5. #5
    I think it has more to do with the stiffness of the Rail over a Rod than adding or derogation anything to the model. Rail catches may have Buy Cheap Essay Online marginally littler effect on HPR models than tube type carries.

  6. #6
    Davo. Its not that I'm skimping on the frame. The base of the frame is the table, but I'm building up the frame to be a lot stronger and sturdy than just the table... Take a look on instructables at printtable you'll see the design i'm using as inspiration. Just as a coreXY system.

    I'll have a think about the 80/20... I might just use that too.

    Thanks

    Dan

  7. #7
    Super Moderator curious aardvark's Avatar
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    how big a print volume does that have ?

    Looks bloody complicated too !
    I'm definitely sticking to deltas :-)

  8. #8
    I've backed off from the printtable, after i broke a leg trying to attach a linear rail...
    So after a bit of time modding my I3 to improve it, I've come back to the idea of a coreXY printer. And basically, I'm making a large version of Tech2C's hypercube

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