Anycubic kossel extruding in the air

Hi I printed a benchy perfect first time, but went to print another item and the printer is extruding about 2-3cm from the bed then randomly the nozzle will go further down and up from a few cm to scratching the bed, i have the auto levelling module and relevelled the bed, remeasured the z pos and input a new z offset but afterwards it still prints mid air and goes up and down by a few mm when its printing. The z offset seems weird as previously it was around -16.4 but now its around -1.7. Please help I've been trying to fix this for a while and I'm fairly new to printing so tell me if I'm being stupid!!!
Thanks so much Frazer.

Edited 1 time(s). Last edit at 02/23/2018 12:36PM by frazercampbell.

1) Check belt tensions and puleys + tight the screws on the motors
2) At next, try to find out at which axes it is loosing steps
3) FInd aprropriate stepper driver and turn its resistor trimmer just a little counterclockwise (just about 1/8 - 1/4 of turn) Be gentle!!! - it can be easily broken by the screwdriver. This should put more power on that stepper motor
3) If this doesn't work, swap that stepper driver with the 5th one. If your printer kit is the same as mine (there was many changes made by the manufacturer) the 5th stepper driver is there left as spare.
4) At least try to swap motor cable if it's not broken.

If you'll be lucky enought, you'll not have the same problem as me. Right now I have the same symptoms on my Anycubic Kossel Linear Plus.

My printer worked just fine for about first 8 prints. Now it prints ok at first 2-3 layers and after that one motor starts to skipping steps / failing every second or so and printing goes totaly wrong.
I've already tried all these steps, but it looks like motor is failing or overheating. New stepper motors set is on its way, but it's a little more expensive than the new stepper driver or motor cable

Good luck!

So it could be a stepper driver problem, you say? I have an Anycubic Linear Plus, and the effector thinks that my bed is higher on the towers than towards the center, and not even calibration will fix it!

I did everything from upgrading to RADDS 32-bit hardware, the Duet3D Smart Effector PCB, to Magnetic Effector Rods, and through all of that, I kept the old A4988 steppers. I'll buy some TMCs, and I swear to god if it ends up working I'm going to go suck start a shotgun out of a perfect mixture of rage and frustration.

And here I thought I built the machine poorly. Maybe, I'll redo that too.

Edited 3 time(s). Last edit at 03/05/2018 03:12AM by Lobotomy.

If there is only problem with center height against outer radius, see this video:
[www.youtube.com]

...and calibrate your printer's DELTA_SMOOTH_ROD_OFFSET


This is what I have in config (for Anycubic Kossel Linear Plus):

  #define DELTA_HEIGHT 284.9 // get this value from auto calibrate <- ONLY ALU-HOTBED with sticker - NO GLASS PLATE

  #define DELTA_ENDSTOP_ADJ { 0.0, 0.0, 0.0 } // get these from auto calibrate

  // Center-to-center distance of the holes in the diagonal push rods.
  #define DELTA_DIAGONAL_ROD 268.0 // mm

  // Horizontal offset from middle of printer to smooth rod center.
  #define DELTA_SMOOTH_ROD_OFFSET 186.0 // mm

  // Horizontal offset of the universal joints on the end effector.
  #define DELTA_EFFECTOR_OFFSET 31.0 // mm

  // Horizontal offset of the universal joints on the carriages.
  #define DELTA_CARRIAGE_OFFSET 20.6 // mm

  // Horizontal distance bridged by diagonal push rods when effector is centered.
  #define DELTA_RADIUS (DELTA_SMOOTH_ROD_OFFSET-(DELTA_EFFECTOR_OFFSET)-(DELTA_CARRIAGE_OFFSET)) //mm  Get this value from auto calibrate

But use these values only as a refference and don't think that all chinesse parts have the same dimensions

Good luck

I have a Anycubic Kossel too. And I have this exact problem once. I think.

In my case, after auto homing, the effector would go up to the top most position, and my Z position on the LCD would be something like 295.xx.

Everything was fine for a period of time, until one time I turned on the printer and did the auto homing, the Z position mysteriously became 270.

I did not realize it then and started printing, and of course my nozzle is printing in the air because of the wrong Z position.

I have to redo the "Measure Z Pos" and the whole Auto Bed Leveling process to fix my problem.

I am using stock firmware and I do not know why this happened.

Hope this would help.

Interesting,
but it sounds like bad values in EEPROM it can be fixed with M502, M500, M503 G-codes to return hardcoded values to EEPROM.
With EEPROM I had so many strange problems before I start using this g-code sequence to erase it

Edited 3 time(s). Last edit at 07/13/2018 02:52AM by kubik256.