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Problem with x-Offest shift shortly after starting printing

ufodoctor3ufodoctor3 Posts: 60๐ŸŒŸ Super Member ๐ŸŒŸ
Dear Forum
In principle the JGaurora a5 works fine, but I observed servel times that the x-axis gets an Offset 3 to 5 mm shortly after printing at the height z of about 1mm. The model is well glued to the platform!
The glass-platform is well heated  and fixed firmly by clamps to the Alu-Platform
It seems that the x-axis step motor  losses the track by unknown reason

Do you know this Problem? Can you give me an advice?
Thanks
Peter


Comments

  • Samuel PinchesSamuel Pinches Posts: 2,840Administrator
    Hi Peter, there are a few possible causes for layer shifting. Please see the FAQ page on the wiki. 

    Https://jgaurorawiki.com/A5/FAQ
  • ufodoctor3ufodoctor3 Posts: 60๐ŸŒŸ Super Member ๐ŸŒŸ
    edited December 2018

    Dear Samuel

    Thank your advice! If the two horizontal guide axis are well lubricated by an oiling spray, the sledge moves fine and the often observed horizontal โ€œroubleโ€ with heavy vibrations appears less often which provokes later a permanent offset for the upper layers. Thus, I feel the problem here is a โ€œtiltingโ€ problem, because the three guiding bearings (two at the top, the third below) are too close together with not enough gap to the axis With enough gap between axis to bearings and good lubrication it works fine, but excessive gap would affect the positioning accuracy Thus I think a redesign is needed with better positioned of high quality bearings! Regards Peter
    Post edited by Samuel Pinches on
  • Samuel PinchesSamuel Pinches Posts: 2,840Administrator
    The quality of bearings that JGAurora uses ... could be better :expressionless: ...

    I organised a bearing set from a better quality manufacturer here: https://jgaurorawiki.com/essentials#great-upgrades

    I also suggest you check your stepper driver tuning. https://jgaurorawiki.com/a5/stepper-drivers


  • WerewolfWerewolf Posts: 27Member
    Hello, Samuel,
    I saw your video about comparation original bearings of A5 and similar bearings of brand supplier.
    Have you install these "brand" bearings in printer? Has it some effect for decreasing the woubling on X-Y axis?
  • Samuel PinchesSamuel Pinches Posts: 2,840Administrator
    @Werewolf - I noticed a big improvement in the noise on the y-axis. I do not have any major wobbling on my A5, since I replaced the bed springs with solid nylon spacers. I would recommend you investigate this as a source of wobbling. I am planning to eventually do a before after video with the stock and upgraded bearings, but due to lack of time, I can make no promises about when that will be done, sorry.
    Thanked by 1aestrems
  • aestremsaestrems Posts: 33๐ŸŒŸ Super Member ๐ŸŒŸ
    @Samuel Pinches +1 for this before/ after video with this ubgraded bearings, let's us know when is online, take your time 
  • WerewolfWerewolf Posts: 27Member
    Yes, Samuel, your video will be very expected. And please more detail about "solid nylon spacers"  :)
  • ufodoctor3ufodoctor3 Posts: 60๐ŸŒŸ Super Member ๐ŸŒŸ
    Dear Samuel
    Thank your advice!
    You are right, the bearings are suboptimal and because the 3 bearings are too close together, a slight tilt provokes a stick. But if the axis are carefully cleaned and lubricated,it works fine now without rattle!
    Please look at the following operation instructions and tell me how it can be improved for beginners as I am! Thank you
    Regards Peter

    3D Printing Instructions for JGaurora 5

    PAN, Dec 12th, 2018


    Introduction

    The JGaurora 5 is great, but needs some care!

    Here my tips after many successful and also sometimes failed experiments.


    1. Lift the extruder about 200 mm with the โ€žMove zโ€œ command so that you have full view to the extruder nozzle.

    2. Clean the horizontal guiding axis with isopropylene using a Kleenex paper. When dry again, lubricate the axis with an oil or Teflon spray. My printer rattled heavily after some few printing, provoked an offset at z= 2 mm!

    3. Preheat the extruder to the temperature which was used for the last session, e.g. 270 deg for ABS. Clean the nozzle with isopropylene using a Kleenex paper. The nozzle should be completely freed from any old particles! Check the cleaning process with a small mirror, as used by dentists.

    4. Start the printer, but stop just at the moment then the temperature for bed and extruder is accomplished.

    5. Check if the the platform (Glass or CCFREE layer) is clean.

    6. Start the leveling with 2 sheets of paper (2x0.12mm). Check if the papers shows a slight resistance when pulling out. Make a second leveling test with only one sheet of paper, should be free when pulling out!

    7. Start the printing command and observe the printing of the very first layer. The hot filament should glue perfectly onto the platform, without additional threads or knots! If the first layer looks poor, stop printing and repeat point 3!

    8. After successful printing wait about 10 minutes for cooling down. Remove the printed object with a sharp scraper and a 0.2 mm steel leaf. DO NOT hammer onto the scraper when the object cannot be removed, the xy mechanism is delicate!Remove the building platform from the printer at handle it on a clean work bench. Sometimes a preheating of the platform to 80 Deg helps!

    9. Measure the height dimensions of the printed item. A tolerance of +/- 0.1 mm is OK for objects <10 mm.



  • Samuel PinchesSamuel Pinches Posts: 2,840Administrator
    2. For printer lubrication, there are a range of substances that are suitable. I suggest considering some others too:
    https://jgaurorawiki.com/lubrication

    3. I do not recommend heating the nozzle above 250C. The PTFE insulation will break down, producing toxic vapours. Please research this for your safety.

    6. For getting the prints to stick, I have written a guide which has been successful for me and others. You may note, I only use one sheet of regular copy/printer (75-85gsm) paper.
    http://jgaurorawiki.com/a5/bed-adhesion

    Otherwise, I think the rest is sensible :-) 
  • ufodoctor3ufodoctor3 Posts: 60๐ŸŒŸ Super Member ๐ŸŒŸ
    edited December 2018
    Dear Samuel

    Thank you very much for your professional advice! I am still a beginner in 3D printing technology!

    With trial and error, using the materials ABS, PLA and TPU, I got sometimes acceptable results, but with poor repeatability!

    After perfect cleaning of the nozzle the gluing of the first layer onto the bed (I am using the CCtree from GearBest) is still a problem.

    A printerbed temperature for PLA and TPU of 50 Deg (You say 67 Deg), and for ABS of 80 Deg seems to be optimal.

    Only ONE sheet of regular paper (0.12mm) for levelling is sometimes ok

    You mentioned that the first layer should be printed with slow speed about 10 mm/sec. How to program this in Cura for the first layers, but 30 mm/sec for the following layers?

    Thank you and best regards
    Peter
    Post edited by Samuel Pinches on
  • Samuel PinchesSamuel Pinches Posts: 2,840Administrator
    edited December 2018
    Hi Peter,

    First, you need to show all the settings. Then you can find the first layer speed as a separate option:



    Post edited by Samuel Pinches on
  • ufodoctor3ufodoctor3 Posts: 60๐ŸŒŸ Super Member ๐ŸŒŸ
    edited December 2018
    Dear Samuel
    Thank you very much for correcting my amateur tips!

    The JGauroa print now TPU, PLA and ABS quite well!

    I have now a collection of samples with documentation about the settings: Temperature Extruder/Bed, Layer thickness, Skirt or Brims at the bottom to get fixed onto the platform, Number of papers for levelling (1x 0.12 and 2x 0.12)

    For experimental purpose I print small object, cylinder diameter 20 x 5 with some gaps and holes.

    TPU an PLA works fine, but ABS objects are not well glued together: The final cold object gets separated by little applied lateral force at z=1mm or higher.
    There is a solid lower base layer of 1 mm and a solid upper layer of 4 mm, but not connected firmly  connected!

    Settings for ABS:
    Extruder: 240
    Bed: 100
    Layer: 0.1 (0.05 is a little bit better!)
    Levelling: 2 Papers = 0.2
    Support: Skirt and also Brim

    Please give me advice, Thank you
    Peter
    Post edited by Samuel Pinches on
  • Samuel PinchesSamuel Pinches Posts: 2,840Administrator
    edited December 2018
    Hi Peter,

    For ABS I would suggest trying 250C, that will make the filament hotter, so that it can cause the previous layer to be heated sufficiently for good inter-layer welding. Also, I would suggest to turn the fan off. ABS is generally best to print in an enclosure, so that the ambient air temperature can be increased, and that convective cooling can be reduced. Tip: Many people make DIY enclosures from the IKEA Lack tables.

    Cheers, 
    Sam
    Post edited by Samuel Pinches on
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