Hi folks, I suspect that something is wrong with my x axis. When I print a wall, I see every 30 layers or so some kind of horizontal scares all long like if the filament was not extruded or aligned properly, then on next layer it is fine again. Watching the printing i see that the pulley is slightly wobbling, like if there would be some slight difference between the pulley steps and the gear that would make it struggle.
Also, when I move manually the carriage it feels like every full stepper rotor revolution, there is a resistance. I would really like to know if somebody ever had this? Is it the pulley? Trough time it got stretched? Or is it the stepper? I’m quite reluctant to replacing the stepper there. Looks like a difficult task to get everything back in place after it 
Thanks
PS: probably a coincidence because x axis quality issued existed before but I got my ffboard rev b replaced by a rev d which is running sailfish creator pro. I do not think it is any issue ( same schematics, just sturdier design on the pro) but I mention it just in case.
Follow-up. X axis pulley and gears completely dissasembled stepper tested, gears cleaned, and now everything is running very smooth, no wobbling, no resistance… But same artefacts. I guess I’ll try my Y axis then. But I noticed that the scares are forming a repetitive pattern. And that is All around the part, not just X axis. And on every next affected layer, the pattern is being repeated, only with 6 mm or so excentered to the left. and so on. I do not see why it would happen. But my focus is now moving to the extruder. That would underextrude every and so on a repetitive cycle. Mmmmmm… Maybe the spool???
Hi, check the spool first if is getting stuck. But if it is really repetitive it may not be the spool, then yo have to check your nozzle, if it has some blockage by printing a very flat thin object, about 3 layers, and check if pattern is showing, if it does you may have a blocked nozzle. The last to check are your pulleys and steppers. By the way what temp are you running your extruders at, and what material are you using?
What I noticed so far is that it is VERY repetitive, attached another picture showing how constant it is. It’s showing only one side of the part, but There are more scares around it so after I checked under another angle it appear that sometimes layers are all fine for a while, then sudenly, you would have some “morse” ripping one layer every few centimeters. It also looks like the interval between “healty” layers and one bad layer is quite (but not perfectly) regular.
I’m printing PLA at 230° (I know it is unnecessarily too high, S3D saved it like that despite setting it to PLA and I was too lazy to rebuild it. I thought that amongst all possible causes, temperature would not match these repetitions).
So. You think a nozzle can be the cause of a dual clocked weird pattern? I’m going to run cleaning filament in it, then print a flat test part as you said, that’s an excellent idea. Thanks!
You may want to check the drive wheel in the extruder. Plastic gets caught in the groves and it doesn’t feed even. Preheat the nozzle and push fililment though. Wipe the nozzle. Then level bed again. I go through little things like that all the time but I print a lot. Everything the other guy said is good also.
Hi @wesman732, hi @3dprintwiz,
Well, As much as I think that the drive wheel is a very good lead, and as much as I also thought that wesman732 test suggestion to check if it is extrusion related was also an excellent idea, I am ashamed but I’ll have to declare 2 thinks:
1) Problem is solved;
2) I do not know why the problem is solved.
Even before I had the time to do the test, when I went down to the basement to check on the last print I launched while I was writing my previous post in this very topic, the printed part was perfect! No scares no more. Not even any residual shadow of the previous existence of that “bug”. I mean: previous part: all buggy. Next one, perfect. And next ones, perfect too. Go figure.
I do promess that if that thing happens again, I’ll do your suggestions and post what solved it.
Anyway, thank you for helping me and other readers facing similar issues! 
Laurent
