@ThantiK you are looking at the man who broke a spark plug tightening it in the engine 
So in my case if something is tightened it stays there. Plus, I have checked - the sharpie marks on shaft and pulley did not move against each other during the whole operation.
@Alan_Weber the motor is hot - with the latest driver adjustment - but not too hot. About 57C is the max I have measured on it, but mind you - I am not able to do long prints. It was skipping steps when it was much cooler though, and actually now that there is much more amps provided to it it skips less often - but does so nevertheless. And I canât say the skips match any particular position on the belt, like skipping in a predefined number of layers - not really. Last thing last night I tried to print was a tube cap, which managed to make it almost to 3/4 height - about 1 cm. So no relation to teeth of belt, nor to rod shape.
Try this, do a dry print. Either remove the âEâ extrude commands from your gcode, or disconnect the extruder motor. Then print, carefully watching to see if it skips. Alternatively you can set the extrusion multiplier really low, like 0.5 the idea here is that you may be over extruding, and the nozzle crashes or gets stuck in a print. Also make sure your travel speeds arenât too high.
I had to lower my acceleration to 300mm/s when I was using underpowered motors. And if the belt is rubbing against anything, that is a problem. My belt used to rub against the side wall next to the idler pulley, but only in one direction. Adding a guide glued onto the idler bearing fixed this.
The motor current should be set to where you bring it up, and then gradually lower it until the motor loses steps. Turn it up just a little past that until it moves again, the just a tiny bit more past that. Too much current is just as bad as too little.
Try switching your X and Y axisâs (axises, axi, axis(s)?) and end stops. If it still skips on the X axis, it must be mechanical⊠if the Y axis starts skipping, itâs electricalâŠ
@Igor_Larine ⊠Your axis is âslippingâ either electricly or mechanically. As others have mentioned, current being too high/low can cause problems. Your jerk/acceleration settings can also cause problems.
Iâd say cut your jerk/accel numbers in half. If that stops the skipping you can probably bump your numbers up a little at a time until the problem returns.
You can also check for mechanical issues by marking a single line on the belt, pully and motor shaft in the home position. Run a small print and see what doesnât line up!
Good luck!
Hourray! It seems to have been vanquished! Separated the endstop and motor wiring - actually ran them along different walls to the motor. Wound as many coils as I could of the motor wiring around the ferrite ring - next to controller this time. Works for the moment! Even tuned voltage down a bit - from 1.3 to 0.85 - still works and does not miss steps! Now to more tuningâŠ
Thanks for your input everyone!
@Alan_Weber axes
@Igor_Larine I had a similar problem and it was heat related. The driver was too hot and it shuts down as a precaution. I put a piece of aluminium touching the heat sink and it stopped the misses. 44C is not high at all thoughâŠ
@Jose_Alcerreca
heat and driver problems were the start of it - I had a driver from sainsmart on that axis, and it started overheating like something unbelievable. And made the motor overheat as well⊠And missed steps. Then I installed another driver - from geeetech, and that one worked like it should. I also have radiators on all chips now, as a precaution.
@Matthew_Satterlee
electrical it was. Mechanical problems were the ones I eliminated almost entirely before posting here - but lack of experience did not allow me to believe such an insignificant detail like putting endstop (which, by the way, is an NO) wires together with motor wiresâŠ
@Stephanie_A no overextruding for me - got that part figured out a bit already Could well be underextruding in fact, have to run tests to see. Belt rubbing - now that I have the machine back in shabe I am thinking of an idler cover for GT2 (http://www.thingiverse.com/thing:82490) and maybe a larger pulley with more teeth and also some walls - if printed close to the width of the belt, sould keep it away from the wallsâŠ