1. Got a question or need help troubleshooting? Post to the troubleshooting forum or Search the forums!

Tapered z coupler

Discussion in 'Projects' started by 1d1, Jul 16, 2014.

  1. 1d1

    1d1 Active Member

    Joined:
    Feb 21, 2013
    Messages:
    418
    Likes Received:
    216
    Here is a pic of 5mm to 8mm tapered, self-centering rod couplers that I printed in Polymax PLA. When I (finally) receive my bed upgrade, I intend on replacing the stock ROBO couplers and see how well these work. The will fit any 5mm stepper motor shaft and either 8mm or 5/16ths threaded rods. The tapered nuts over the tapered threads both center and firmly attach the z rods to the motors. Please disregard the quality of the print as that ribbing is just what the couplers are designed to minimize. If anyone is interested, I will post the .stl files for both parts. It was originally designed by "loco" and posted on Thingiverse as a 5mm coupler on either end. I just modified it to fit our ROBO z rods. It seems to hold really well in testing but I will probably either glue or tap a set screw for the actual fitting. Tapered coupler 5-8mm.jpg
     
    2 people like this.
  2. 1d1

    1d1 Active Member

    Joined:
    Feb 21, 2013
    Messages:
    418
    Likes Received:
    216
    Bump
     
    2 people like this.
  3. Ziggy

    Ziggy Moderator
    Staff Member

    Joined:
    Feb 20, 2013
    Messages:
    707
    Likes Received:
    530
    Curious to see how you go.

    But TBH the helical couplers modded with a thrust ball bearing work very well and will definitely help cure your Z ribbing problem. See the thread Z Axis - known issues and fixes.
     
  4. 1d1

    1d1 Active Member

    Joined:
    Feb 21, 2013
    Messages:
    418
    Likes Received:
    216
    I'm well aware of the ball bearing mod but I also like the self-centering of the printed coupler. They aren't very "sexy" compared to machined helical ones, but worth a shot. The ribbing on my current set up is only problematic @.2 resolutions (as pictured). Smaller or larger things go well enough not to mod at all... but then it wouldn't be a ROBO, would it? Still waiting on the bed upgrade and getting a bit impatient with that whole mess. I ordered the day I received the e-mail announcing its imminent release and, months later, still waiting with no word from headquarters - except having my credit card charged right away. I wish ROBO would get its CS act together. I would have thought they would learn from the past, but it certainly isn't yet evident.
     
  5. SteveC

    SteveC Well-Known Member

    Joined:
    Jun 12, 2013
    Messages:
    894
    Likes Received:
    316
    1d1,
    I also ordered the bed mod the day I got the email and have not heard anything.

    Nice coupler design. What software package did you use?
     
  6. 1d1

    1d1 Active Member

    Joined:
    Feb 21, 2013
    Messages:
    418
    Likes Received:
    216
    I used Tinkercad to modify the Thingiverse files of this design. So, I didn't design it at all, just made it to fit our ROBO setup.
     
  7. SteveC

    SteveC Well-Known Member

    Joined:
    Jun 12, 2013
    Messages:
    894
    Likes Received:
    316
    Thanks,
    I was interested in the threaded parts. I have modifed them but have never created them from scratch. I've been using Sketchup and 123D Design. I use Tinkercad for a class I teach, it's pretty good for a free cloud based tool.
     
  8. 1d1

    1d1 Active Member

    Joined:
    Feb 21, 2013
    Messages:
    418
    Likes Received:
    216
    There are scalable thread files on Thingiverse (among other sites) and it would be possible to implement a tapered mod in 123D, I believe. That would be a fun class project. Tinkercad has been adequate for my needs though it isn't a high precision engineering tool. I enjoy getting myself to think about how to implement primitives to do what I want. It is actually quite a powerful program and has been greatly improved since its inception. I am printing a new design right now; I should post it when finished because it is an interesting object. Anyway. Hijacked my own thread...
     
  9. SteveC

    SteveC Well-Known Member

    Joined:
    Jun 12, 2013
    Messages:
    894
    Likes Received:
    316
    I never get concerned about minor thread hijacking like I just did. I'ts a way to get interesting discussions going that can start new threads.
     
  10. 1d1

    1d1 Active Member

    Joined:
    Feb 21, 2013
    Messages:
    418
    Likes Received:
    216
    OK. Installed these today and am liking how they work. The couplers fit snuggly and to the bottom of each shaft so it is essentially a rigid system - no ball bearing necessary. I hadn't removed the threaded z rods before and was surprised at how much play (once the set screw was loosened) there was in the helical coupler. With the printed couplers installed, both z screws stand straight and parallel. When just moving the carriage up and down, there is a very small amount of wobble at the top, but far far less than with the helical couplers. Right now I am printing 20 cable chain links at once and there is no evidence of wobble or ribbing at .3 resolution. I also cleaned the z screws, installed nylon nuts and dri-lubed everything. I'm pleased.
     
  11. 1d1

    1d1 Active Member

    Joined:
    Feb 21, 2013
    Messages:
    418
    Likes Received:
    216
    Finished a print of 20 individual chain links for a cable chain and they are very nice. Visibly better than what I had been printing with the helical couplers and honestly, I was already happy with my prints. Now I'm happier. I did not change my motors to constantly on (no auto level here) or any other hardware that would matter in this regard. I'm thinking that a stable, rigid connection (of any sort) between stepper motor and threaded rod (nope, no metric rods either) will improve results. Printing our own parts on our own machines - isn't that at least part of why we do this?
     
  12. Peter Krska

    Peter Krska Active Member

    Joined:
    Nov 30, 2013
    Messages:
    766
    Likes Received:
    229
    Pics?


    Sent from my iPhone using Tapatalk in Canada
     
  13. 1d1

    1d1 Active Member

    Joined:
    Feb 21, 2013
    Messages:
    418
    Likes Received:
    216
    Here you go, Peter. The Macro shots tend to highlight the defects. To my eyes, the differences are clear, but not quite so pronounced. The first piece is still completely functional in all regards, but the with the new couplers, it is functional and pretty... sort of, anyway. The overview of the printer shows how straight and parallel the rods are now. I was going to make a top piece for each side, but don't think it is necessary at this point. 20140904_155038.jpg 20140905_080100.jpg 20140905_080158.jpg
     

Share This Page