I have recently assembled a vertex k8400, and managed to get several good prints out of it (new filament spool, bag clips, etc) all with good quality.
One day, the printer started making a “DDDDDD” type noise (the one the steppers make when they can’t complete a step?) and then the layers on the print would be shifted on the y-axis.
-No settings had been changed between the good prints and the shifted prints.
-The rods have been checked and are parallel/perpendicular to each other.
-The Y-Axis stepper has it’s belt pulley securely attached.
-The belts are not too tight (loosened them slightly, as they did feel a bit tight earlier, although this did not fix the problem).
-The belt clamps for the Y-Axis have been spaced out a bit more, as suggested by others on this forum.
(This fix fixed our first issue, which was the extruder carriage binding at the home position, the X-Axis was tight.).
I am now at a loss as to where/what to check now. Any tips would be appreciated!
I went thru these issues as well and it always was mechanical for me : pulleys (loose), belts (too tight) and axles (have to be parallel, oil required)
Also reseated a little bit the X & Y stepper motors, more relaxed
Hope this helps
Benoit
Having the same issues here, in x-axis direction. Have everything lubricated, nice but not too much tension on the belts, all is aligned and just now halfway through a 4.5 hour print it shifted. Print is worthess… The machine exists because of it’s acuracy. i sliced it on slow (in Repetier) condition and still it drifts off (don’t dare to think what it would do on fast…:S and there doesn’t seem to be a way to make it even slower). I secured all pulleys thoroughly again and again because it’s not the first time. I’m pretty sure it’s in the steppers. Not in the pulley’s etc. I also hear the DDDDDDD-noise as described. It’s certainly comming from the stepper. Also loosened and moved a pulley to the side to check for damage to the shaft. The setscrews would have left a mark around the shaft if they were not fastened well enough. There was no mark around the shaft so it has to be the steppers.
alright, playing Simply Red now, so calmed down a bit lol. Anyway, i disconnected the belts to see how the extruder moves. though the rods(350) are parallel because of the construction, the wagon gets resistance in the back when it moves over the y-axis. It moves smooth in the x-direction. So having more mysteries here instead of more insight in the problem. I measured the corners diagonally both ways to check if the frame was built perpendicular. Both ways i read about 499mm so thats good. If all is nice and straight and the rods are supposed to be parallel but aren’t, the only thing i fear to conclude is that something has to be bent. please let me know if my reasoning isn’t watertight here
going on that, i let it run left and right without the wagon attached to see if it wiggled (one of the 350 rods might be bent. even a slight deviation would show) but it didn’t.
Next, logically, move it over the y-axis. the 350-rod in the rear has a slight wobble. This is a discovery that might get me somewhere for 2 reasons:
i focussed on the rods being parallel but forgot about the z dimension. if the rear rod has a deviation of about .5mm (which is of course a guess, but i do dare to say it isn’t more than that) then the outer rods may be parallel in all ways, the middle rod (the 289 or the 298) is either going up or down due to the wobble in the rear rod. i checked this by putting the wagon on the outer left and see if it still has a certain resistance in the back end. it had, so there’s more going on:
The second reason finding out there’s a wobble in the rear rod is important is pretty simple: if something is bent, more can be bent. i checked all 4 350 rods as mentioned above and only the rear is bad meaning there’s only the 289 and 298 rods left to check. I’ll disassemble them and roll em on the table. If you’re still reading, i’ll keep you posted:) please let me know if i’m going about it all wrong.
okay, i fully disassembled the drivework of the printhead, and like i expected after last nights discoveries, some shafts were slightly bent, and because it is easter and everything is closed around here i took the onorthodox method and straightened em by hand. It worked out so well that now it runs like a clock. One more thing i gave attention to is the tention of the short belts (from the stepper to the rod) i think anyone who has ever changed an alternator-belt of a car that has not got a tensioning mechanism (which imho should be severly punishable) might have put them too tight. Of course it isn’t a v belt so that kind of tention is unnessecary.
During assembeling it all i took good care not to make it too tight. Like i said, it runs like a clock:) having the rest of this long weekend left to make some prints:)
For me the solution was to take all the rods out, check the distances between the rods, and adjust the position of the black sliding blocks on the printerhead. (Distance in the manual is not correct.) After that, reassemabled it, and found that i could slide my printerhead from one side to the other using only a bit of force on 1 finger. (ie: very smooth movement.) Then i aligned all the belts again, and retightened it. That solved the problem.
