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I have a new Tevo Tornado, which I have completed two good prints with, a 20x20 test cube from the supplied SD and the spool holder also from the SD. I say this to note that the printer was capable of producing a good print.

Print 3 was a design I created in Fusion and it printed badly, very disappointing holes missing. Stringing gaps between material just rubbish. I downloaded a simple print from Thingiverse just to see if it was my poor design skills or the printer and that came out just as poorly: lots of strings between details. Both of these were sliced in Cura. As that doesn't have a tornado driver, I downloaded one from the support group and the prints have not even started properly, see pictures for example.

I might be going down rabbit holes here but this is what I have found and tried:

  • 1 relieved bed - done to ridiculous degree of accuracy, cold gross levelling then bed and nozzle at PLA working temp using feeler gauges. I have done 0.1 mm, 0.15 mm, 0.2 mm

Now I have added to the suspicion the z axis coupler see images below:

z axis flexible coupling#1z axis flexible coupling#2

z axis flexible coupling#3

YouTube videos, that I have seen, show couplers that are not a spring - any thoughts? I would certainly appreciate the time anyone has to impart their knowledge.

EDIT 1: (Additional information posted as comment, now moved to question)

The print bed is brand new from Tevo the unit has only done a few prints most aborted, and I also thought perhaps a residue from the feeler gauges had contaminated the bed, but I have cleaned it with alcohol wipes and also tried putting prints on to unused parts of the bed. You are right the g-code from the test print was from an unknown slicer, no doubt tuned by the manufacturer the part I designed in Fusion was sliced by cura. I have since tried the original test piece and it fouls the extruder nozzle almost straight away.

The main differences and there are not many between the set up parts, are that the Cura code does a G92 E0 G1 F1500 E-3.5 before starting layer 0 (both set z0,3). The test piece just does a G92 E0 G1 F7200 the feed rates are different the cura print sets M204 S500 and the test sample sets no acceleration. I assume there is a default in the Marlin firmware.. there is no doubt some globs of PLA stick like in dots between the strings, but the extrusion between direction changes do not kind of like join the dots where dots stick and joins don't.

I am going to change the coupler because, well, I don't know what else to do. Replacing it with a better one can't help. Other things I have thought about - PLA temps - I have gone up the whole range according to the manufacturers bandwidth in 5 degree increments no difference I have also done some bed changes but neither hotter nor colder (it's 30°C and humid at the moment, so maybe a materials property issue, but then again no difference in conditions between a successful first test and all the messes). I am storing the PLA in a gel bead box to reduce humidity. still basically stumped!

EDIT 2: (Additional information posted as comment, now moved to question)

Thanks for your observation, it's a new bed and I clean down with alcohol wipes ( isopropyl) I don't think I have ever put a finger on the bed - very aware of that. While I don't know what I am talking about on the one hand I am semi convinced it is not the bed, anyway I am going to get a glass bed in part to deal with the protruding screw head issue.

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  • $\begingroup$ The images that you refer to showing your print are missing, and two of the images (1st and 3rd) showing the coupling are the same. Please add the images of the print (using the add image button in the editor). $\endgroup$
    – Greenonline ♦
    Commented Jul 24, 2018 at 20:49
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    $\begingroup$ Maybe related 3dprinting.stackexchange.com/questions/4755 but the question is incomplete without a photo of the problem $\endgroup$
    – Sean Houlihane
    Commented Jul 25, 2018 at 15:53
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    $\begingroup$ Hi ventis! We are aware that you cannot comment on either your question or answers generated by the community, but you cannot use someones answer to add your information, instead you should use that information to make an even better question so that people can change their answer and others can add new answers, all to help you fix the problem. By doing this we record your problem and the solution for eternity, that is what sets SE sites from regular forums. I copied your reply into your question, I'll leave it up to you to redefine and restructure the question. $\endgroup$
    – 0scar ♦
    Commented Jul 25, 2018 at 19:37
  • $\begingroup$ Ventis, as 0scar says, please add comments to the answers provided (or, better still, update and refine your question), instead of editing the answers and adding a comment there. It is way too confusing. Even though you have less than 50 reputation points you are still able to comment on your own question and other answers to your question. See Why do I need 50 reputation to comment? What can I do instead? $\endgroup$
    – Greenonline ♦
    Commented Jul 25, 2018 at 22:01
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    $\begingroup$ There is still no photo of the actual failure. This question is very hard to answer as it stands. $\endgroup$
    – Sean Houlihane
    Commented Jul 25, 2018 at 22:28

4 Answers 4

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The "springs" connected to the stepper motors aren't a problem. They are special shaft couplers which allow some relief if the motor mounts are not strictly perpendicular to the lead screws. They are very rotationally stiff and allow just a little bit of misalignment between the shafts.

The first two prints were from the SD card. You didn't talk about slicing from an STL file, so it is possible that they were pre-sliced for this machine. Every G-code file has introductory code that initializes some aspects of the operation. Check the "preamble" code at the front of the files you have sliced. Are there commands that look different? Is the Z parameter for the first layer different from the pre-sliced files? Are there G-codes missing from the files you sliced?

If you are trying to understand what the G-codes do, this resource may be helpful. Some possible commands could be commands to limit acceleration, jerk, speed, or introduce offsets. Also check that the temperatures are being set correctly in the G-code you generated.

If you had sliced the files on the SD card, then double check that the parameters were the same. Try re-slicing the object and comparing the G-code that is generated.

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  • $\begingroup$ Slicing can only have limited impact on layer 1, but these are all good things to check. $\endgroup$
    – Sean Houlihane
    Commented Jul 26, 2018 at 10:52
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Based only on your title, and not on the content of the question, I would guess that maybe your print bed is not clean any more, and this is causing bad adhesion.

There are lots of bed surface material options - I guess you have some specially engineered high stick surface on this printer so you should check the manufacturer's specific direction regarding the print material since there is a risk (eg with PETG) of excessive bond strength requiring the use of a release agent in some cases.

I use kapton tape on my bed, and always wipe over with acetone or isopropyl alcohol before printing. Soap/water might also be effective - the problem which you're maybe facing is the oils deposited from touching the bed with fingers.

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Update and close

I have changed the coupler on the z axis and levelled the bed put a print on to test, skirt and first layer look good so I think we can call this one closed and thank you very much for your comments.

so over the weekend I have run a couple of prints, one very successful the other a complete fail, I would however judge the layer 1 adhesion issue to be largely solved by the replacement of the coupler, which was slightly fiddly. What I did notice was in purchasing a new coupler the design used by Tevo has to sets of perpendicular grub screws one for the lead screw and on to locate in the stepper motor shaft. The stepper motor only has in flat face so picking up on this is important and the factory had not - sloppy ! Secondly the lead screw has no faces so I dremeled two peep faces 😀

Once the lead screw was dressed the locking down of the coupler was simple and secure. Took about 30 minutes to fix after days of misguided bed levelling and slicer tweaking.

Old and new coupler new one bought as a pair from amazon £6 could have for them cheaper but I wanted next day not to wait.

Old and new coupler

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  • $\begingroup$ Hi ventis, great that you solved your problem. Could you please update the answer, the current answer you have is rather terse. Please expand which couplers you used an preferably add a picture. We cannot close questions, SE sites operate different than normal forums. We store questions and complete answers so that other people may benefit from them. I encourage you to expand the answer, you can accept it after 48 hours (there is a tick mark near the counter on the left) and people will then vote for the complete answer. Thanks! $\endgroup$
    – 0scar ♦
    Commented Jul 27, 2018 at 18:47
  • $\begingroup$ OK hello, so iver the weekend I have run a couple of prints, one very successful the other a complete fail, I would however judge the layer 1 adhesion issue to be largely solved by the replacement of the coupler, which was slightly fiddly. What I did notice was in purchasing a new coupler the design used by Tevo has to sets of perpendicular grub screws one for the lead screw and on to locat in the stepper motor shaft. The stepper motor only has in flat face so picking up on this is important and the factory had not - sloppy ! Secondly the lead screw has no faces so I dremeled two peep faces 😀 $\endgroup$
    – ventis
    Commented Jul 30, 2018 at 9:11
  • $\begingroup$ Once the lead screw was dressed the locking down of the coupler was simple and secure. Took about 30 minutes to fix after days of misguided bed levelling and sliicer tweaking. $\endgroup$
    – ventis
    Commented Jul 30, 2018 at 9:13
  • $\begingroup$ Such information should be inserted into the answer to conserve for the future! Also the answer is very terse. This is not a forum where you have to comment on other people, instead you update your answer. Please read the help section, accessible through the button with the question mark at the top right menu. Please take the tour and also have a look at the questions and answer to understand how SE works. $\endgroup$
    – 0scar ♦
    Commented Jul 30, 2018 at 9:14
  • $\begingroup$ Hi again Ventis, thanks for the updates. :-) You are able to edit your posts using the edit link just below the post. $\endgroup$
    – Greenonline ♦
    Commented Jul 30, 2018 at 10:03
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What it may useful to improve your prints, are the following elements, according to my personal experience with the Tevo Tornado: 1) level the bed when it's warm. 2) print a cylinder that should measure 100 mm, afterwards measure it with a caliper: regulate the steps per mm according to the difference (many guides for calibration are available, for example: https://youtu.be/Wk3qYOB4E9I) 3) print this object to be installed on the z axis and regulated with an M5 screw and nut: https://www.thingiverse.com/thing:2827664 4) Print a test for temperatures, like this: https://www.thingiverse.com/thing:2131069 I hope it helps. Happy printing.

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