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

Z Axis - precision and accuracy

Discussion in 'Mods and Upgrades' started by Ziggy, Mar 25, 2014.

Page 9 of 12
  1. Peter

    Peter Member

    Joined:
    Jun 20, 2013
    Messages:
    81
    Likes Received:
    40
    I want an advanced twiddling mechanism. 2 controllers for the z motors and some two way toggle switches so i can raise or lower either rod more accurately during the 'panic layer' in say 0.05mm increments without touching the rods.....
     
    #161 Peter, Jun 8, 2014
  2. Mike Kelly

    Mike Kelly Volunteer

    Joined:
    Mar 11, 2013
    Messages:
    6,967
    Likes Received:
    2,276
    Not really possible with the ramps since the Z's share the same line. You'd need a board that has separate drivers for each Z stepper
     
    #162 Mike Kelly, Jun 8, 2014
  3. donhuevo

    donhuevo Active Member

    Joined:
    Mar 29, 2014
    Messages:
    138
    Likes Received:
    100
    I like reaching in there and turning them by hand. It's quick, it's simple, there's no looking away to put the cursor on something. It makes it feel more like art.

    And talking about dubious build quality... dubious is a very nice way to put it. Out of the box, my z smooth rod brackets were broken. The Z end-stop switch was on backwards. My Y-stepper's geared pulley set screw was loose. This was my first foray into the world of 3d printing. I didn't even know I had a set screw down there. So there I was trying to print and wondering what I was doing wrong. Trying different settings in Slic3r. Reading thread after thread after thread. Should I try and do something with that weird ceramic screwdriver??? I know, I'll buy some different filament. Oooooh, maybe the E3D will solve all my printing problems. Nope. Let's try another hobbed bolt.

    I know this sounds like a bitchfest, but here's the thing... I'm really glad the printer showed up this way and not working perfectly out of the box. It forced me to learn the thing inside and out. In my search for answers, I learned a lot more.
     
    #163 donhuevo, Jun 8, 2014
    JoshYourITGuy, Datum, Galaxius and 4 others like this.
  4. Ziggy

    Ziggy Moderator
    Staff Member

    Joined:
    Feb 20, 2013
    Messages:
    707
    Likes Received:
    530
    I am pretty confident that I have found a cure for the Z Ribbing. I've attached a photo of one test print from my Robo which shows the Z Ribbing has completely gone.

    To be more confident that the fix works on other Robos, I've contacted a few forum members to help check they get the same good results. I've also contacted Robo Tech support.

    I really want to avoid everyone trying to replicate the solution I have come up until there is more proof that it works. While I am confident it is a solid solution, I don't want to see lots of people wasting their time (and a little money) if the worst happens and the solution is not completely successful. I hope everyone agrees that's the right thing to do.

    In the meantime I will be writing up the how and why of the fix as there are a number of straightforward changes which need to be made to the Robo coupler configuration and threaded rods, one extra part (readily available) and one firmware change.

    Once we have checked the results, I will make the info available on the forum.

    Mark Tomlinson has been great help answering questions about how and why his Robo does not have the Z Ribbing problem.

    EDIT:Attached a before/after shot of a small hex gear print test. The "before" was printed about 2 months ago.
     

    Attached Files:

    #164 Ziggy, Jun 8, 2014
    10 people like this.
  5. savior2064

    savior2064 Member

    Joined:
    Mar 7, 2014
    Messages:
    47
    Likes Received:
    17
    Thanks Ziggy cant wait to get rid of this ribbing for good.
     
    #165 savior2064, Jun 9, 2014
  6. Paul Yeh

    Paul Yeh Active Member

    Joined:
    Mar 17, 2014
    Messages:
    170
    Likes Received:
    58
    Just want to share the result of my current prints.

    I recently upgraded my Robo3D R1 with the following upgrades, metric M8 x 1.25mm threaded rod, Y axis bed with smooth rod based on Leon's design, and non-flexible Z-axis couplers from Labtek. The results showed big improvements over previous prints before the upgrades.

    On the 20mm calibration cubes, the bottom cube was printed before the above upgrades. The top cube and the right cylinder were printed after the upgrade.

    The z ribbing or z wobbling seemed to be greatly reduced. My guess would be the non-flexible coupler would be the largest contributor to this big improvement.

    The above is not meant to be conclusions of anything.

    I also look forward to Ziggy's findings.
     

    Attached Files:

    #166 Paul Yeh, Jun 9, 2014
  7. Bob64

    Bob64 Member

    Joined:
    Mar 18, 2013
    Messages:
    104
    Likes Received:
    23
    Paul, just checking, but did you change the firmware to keep the z steppers energized? Perhaps that's the last piece of your puzzle...
     
    #167 Bob64, Jun 9, 2014
  8. Paul Yeh

    Paul Yeh Active Member

    Joined:
    Mar 17, 2014
    Messages:
    170
    Likes Received:
    58

    No, I only updated the firmware with the z motor steps of 2560. I did not change the power to the motor to keep it always on.
     
    #168 Paul Yeh, Jun 9, 2014
  9. Ziggy

    Ziggy Moderator
    Staff Member

    Joined:
    Feb 20, 2013
    Messages:
    707
    Likes Received:
    530
    Minimising height variation in the couplers is one part of the solution to Z Ribbing. And these one piece solid couplers will do that of course.

    But a "non flexible" coupler means that something else has to move to accommodate the inevitable misalignment between the motor shaft/rod and the X Carriage.

    It appears that you probably have been fortunate that the misalignment is small on your Robo. Otherwise the Z Axis smooth rods or the stepper motor would be moving to accommodate the misalignment.
     
    #169 Ziggy, Jun 10, 2014
  10. Paul Yeh

    Paul Yeh Active Member

    Joined:
    Mar 17, 2014
    Messages:
    170
    Likes Received:
    58

    Ziggy, you're right. My Robo was not too bad from the beginning.

    After the upgrades, the z-axis threaded rods still wobble a bit, just much less than before. Not sure if this little wobble would be enough to accommodate little misalignment or not.

    I haven't done any large print yet, so misalignment may give me problem later on when I do larger prints. So far, it's looking good.
     
    #170 Paul Yeh, Jun 10, 2014
  11. Peter

    Peter Member

    Joined:
    Jun 20, 2013
    Messages:
    81
    Likes Received:
    40
    #171 Peter, Jun 11, 2014
  12. Bob64

    Bob64 Member

    Joined:
    Mar 18, 2013
    Messages:
    104
    Likes Received:
    23
    I wouldn't drool too hard for those, they'd probably won't fit the x-carriage or the couplers...
     
    #172 Bob64, Jun 11, 2014
  13. Paul Yeh

    Paul Yeh Active Member

    Joined:
    Mar 17, 2014
    Messages:
    170
    Likes Received:
    58
    #173 Paul Yeh, Jun 11, 2014
  14. Peter

    Peter Member

    Joined:
    Jun 20, 2013
    Messages:
    81
    Likes Received:
    40
    Bob64, you are right, not without extensive modification.

    Paul, promising, any proper lead screw is likely to be at least as good as acme style threads. Would also require extensive mods though
     
    #174 Peter, Jun 11, 2014
  15. Mike Kelly

    Mike Kelly Volunteer

    Joined:
    Mar 11, 2013
    Messages:
    6,967
    Likes Received:
    2,276
    I'm just not convinced acme threaded lead screws on the Z axis are necessary.
     
    #175 Mike Kelly, Jun 11, 2014
  16. Peter

    Peter Member

    Joined:
    Jun 20, 2013
    Messages:
    81
    Likes Received:
    40
    #176 Peter, Jun 11, 2014
  17. savior2064

    savior2064 Member

    Joined:
    Mar 7, 2014
    Messages:
    47
    Likes Received:
    17
    Ziggy any news from the others testing out your z ribbing solution. Looking forward to your write up on it.
     
    #177 savior2064, Jun 12, 2014
  18. Ziggy

    Ziggy Moderator
    Staff Member

    Joined:
    Feb 20, 2013
    Messages:
    707
    Likes Received:
    530
    Very promising news.

    A couple of other users have now done the Z Ribbing fixes (one close to where I live) and getting very good results One sent me a pic (below) of a print with a comment (and I quote)

    "I printed the bottom of the part at FULL scale and hot damn, holy hell, dip my nuts in whisky and set 'em on fire, I think my ribbing issue is gone."

    So I am feeling more confident now the Z Ribbing fixes are effective on other machines. But I am being cautious and will wait for some more confirmation before I tidy up my write up a little and put it up on the User Forum.

    If anyone is desperate to try the fixes, just PM me.
     

    Attached Files:

    #178 Ziggy, Jun 12, 2014
    3 people like this.
  19. Mike Kelly

    Mike Kelly Volunteer

    Joined:
    Mar 11, 2013
    Messages:
    6,967
    Likes Received:
    2,276
    Gonna run to ace after work and pick up a couple bearings
     
    #179 Mike Kelly, Jun 12, 2014
  20. Ziggy

    Ziggy Moderator
    Staff Member

    Joined:
    Feb 20, 2013
    Messages:
    707
    Likes Received:
    530
    Any bike shop has them.
     
    #180 Ziggy, Jun 12, 2014
Page 9 of 12

Share This Page