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:
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.