Linear rails on the entire XY assembly?

Discussion in 'Guides, Mods, and Upgrades' started by GrodanB, Dec 8, 2017.

  1. GrodanB

    GrodanB Well-Known Member

    Joined:
    Feb 3, 2016
    Messages:
    205
    Likes Received:
    26
    Hi

    The one part I do not feel is the best on the bigbox is the XY assembly. Mine sags quite a lot. So much in fact I do not think the IDEX with the bed level sensor on the bed support will work.

    So... Is there anyone looking into changing the Y assembly to linear rails??

    Is there anyone updating the Hybrid with linear rails? Or anything for us that is not ready for the IDEX plunge?

    I do not have the CAD skills to fix this myself so I kind of just checking whats out here...

    I'll probably end up with a expansion board for my duet and IDEX... But just looking for a cheaper option and I think I'm not alone in not having the CAD skills to do this and hoping for this... but I'm willing to help and learn...

    This looks like the hole assembly sags:
    [​IMG]
     
    #1 GrodanB, Dec 8, 2017
    Last edited: Dec 8, 2017
  2. GrodanB

    GrodanB Well-Known Member

    Joined:
    Feb 3, 2016
    Messages:
    205
    Likes Received:
    26
    Any comments?

    Bad idea? Not worth the effort?

    All already migrated to IDEX and the rest has sold or scraped there Bigbox?
     
  3. jfb

    jfb Well-Known Member

    Joined:
    Mar 30, 2016
    Messages:
    124
    Likes Received:
    24
    I suspect that most people who are into modifying their bigbox will have already done so. What you're suggesting sounds feasible certainly - I don't see any reason it shouldn't work. The problem of course is that someone will need to do the CAD work.

    As to whether it's worth the effort - I'd say that if you're having that much of a sag issue, then 'probably' :)

    Not much help, I know, but if you can do the CAD or find someone who can/will, then I would say go for it (I've gone another route).
     
  4. GrodanB

    GrodanB Well-Known Member

    Joined:
    Feb 3, 2016
    Messages:
    205
    Likes Received:
    26
    Yes suspected that...

    Just grasping at straws I suspect... My major concern for the IDEX conversion (skipping the obvious money issue) is that the bed leveling is assuming that the bed is flat (Greg's placement below the bed). But looking above I would not called that flat (using a strait edge the bed seems quite flat)

    Looking at the height map above I think that a sagging X/Y assembly explains the maximum in the middle where both X and Y sag is both adding to the problem and corners has the least sag. And upgrading to IDEX only solves the X sag not the Y... I have to assume this is a problem only I have... wonder why?

    well well... owning a bigbox means either live with the old ways or upgrade in the for front... would have liked a middle road for the more slow of us...
     
  5. Mark Curry

    Mark Curry Well-Known Member

    Joined:
    Jan 17, 2016
    Messages:
    98
    Likes Received:
    15
    The autobed levelling on the Duet makes sag a non-issue frankly... I went linear aero as it is much simpler and fairly elegant in comparison to some of the other IDEX designs, and I got bored with the original design. As bigbix becomes more splintered in user spectrum, sooner or later its likely to get done.
     
  6. Mark Curry

    Mark Curry Well-Known Member

    Joined:
    Jan 17, 2016
    Messages:
    98
    Likes Received:
    15
  7. Falc.be

    Falc.be Well-Known Member

    Joined:
    Sep 4, 2015
    Messages:
    262
    Likes Received:
    40
    The only real issue I see is mounting, you will need to drill holes in the frame (or have new sidepanels ladercut) and it needs to be perfect
     
  8. GrodanB

    GrodanB Well-Known Member

    Joined:
    Feb 3, 2016
    Messages:
    205
    Likes Received:
    26
    I do not fully understand the benefit of this remix.

    Björn is making one without loss of build space there I see the remix change but this one used MGN15? or was that just the Block?

    and the benefit is?
     
  9. GrodanB

    GrodanB Well-Known Member

    Joined:
    Feb 3, 2016
    Messages:
    205
    Likes Received:
    26
    For the Y assembly I guess you mean. An setup as today do not work? I was thinking that the Y rails would use modified holder that has the same footprint as the existing ones. But that is maybe impossible.
     
  10. GrodanB

    GrodanB Well-Known Member

    Joined:
    Feb 3, 2016
    Messages:
    205
    Likes Received:
    26
    Since there was a size question and that I yesterday mounted my duex I was thinking about the possibility to have 2 smaller steppers on the y mounted on that backside of the BB. This makes no major difference to the printer since the filament spool already use that space.

    Also one could copy the X axis and have the belt mounted 90 degrees that should also make some space available... And simplify the moving parts. Belt tension can be handled like X axis... Or move the stepper.

    And Marlin duett users could use the z-axis method to run the steppers in parallel.

    Assumption that some holes in the frame is needed to be made anyway.
     
  11. Spoon Unit

    Spoon Unit Well-Known Member

    Joined:
    Sep 6, 2015
    Messages:
    1,142
    Likes Received:
    339
    What specific issue do you hope to solve by "fixing" (or perhaps reducing; gravity is still going to be there) the sag? The only reason to expend effort for me would be for duplicate or mirror printing. I don't have an IDEX myself, but have suspected for a while that a raft might be a good way to compensate for lack of perfect levelling when duplicating or mirroring, but sometimes the intuitive solution is not right and that's not clear until your mind is wrapped around the IDEX way of thinking.
     
  12. GrodanB

    GrodanB Well-Known Member

    Joined:
    Feb 3, 2016
    Messages:
    205
    Likes Received:
    26
    Yes, I do not like the sag. I'd like to really be able to trust in the assumption that the bed is flat and all that is needed is a simple end stop...

    Less work for the printer to compensate less problem more good output... that is my goal.
     
  13. W1EBR.Gene

    W1EBR.Gene Well-Known Member

    Joined:
    Apr 10, 2016
    Messages:
    202
    Likes Received:
    30
    I don't think that you have to implement the design as an IDEX, just eliminate the parts associated with the second carriage.

    I implemented the IDEX bowden design with a modification for Zesty extruders. This design was available before the linear rail design. I also have a BLtouch mounted on the left carriage and use z-axis compensation in the Marlin firmware, which is working for me.

    FWIW, I updated the drivers on the Rumba board to TMC drivers and the fans are louder than the printer now :). I do wonder whether the Rumba CPU is being maxed out, however, the Duet is a step which I am not sure would buy me much and cost me about $320 USD (Duet WiFi, Duex5, display panel)
     
    #13 W1EBR.Gene, Jan 13, 2018
    Last edited: Jan 13, 2018
  14. GrodanB

    GrodanB Well-Known Member

    Joined:
    Feb 3, 2016
    Messages:
    205
    Likes Received:
    26
    The new design for the tool change system is more or less exactly what I tried to explain here...
    Except for I did not look for a tool change CoreXY system :)

    Mounting the linear bearing in the top part (acrylic might need a metal strip running parallel to the bearing on top to act as a protecting part)
    Maybe stand-offs to get the height right...

    And the drive belts below instead of above.

    Then put the Idex gantry on that...

    Oh how I wish I was one with my CAD kung fu...

    That would have been a BB1.5 and I guess that all enthusiast will be in the queue for the new frame... so there is little drive in upgrading...
     
  15. Miasmictruth

    Miasmictruth Well-Known Member

    Joined:
    Sep 4, 2015
    Messages:
    784
    Likes Received:
    117
    Download Fusion 360 its free for a hobbyist, Fusion put out many videos on how to draw up parts, and there are many user videos too. Also if you get stuck they have a good active forum.

    You may not be good now, but its not hard to learn the basics, I have been having a lot of fun learning and now I regularly design jigs for my laser cutter.

    Once you get the foundation down just try to make some of those designs you want, maybe you fail the first few times, but eventually you will get there.
     

Share This Page