Hiccup every 3 rotations on x-as and y-as  

RE: Hiccup every 3 rotations on x-as and y-as

Its hardly visible without something attached to the shaft.

Also, are there any noticeable obstructions if trying to spin it manually ( when motors are disabled in the menu)?

RE: Hiccup every 3 rotations on x-as and y-as

No, there are no noticeable obstructions.

I put the printer together again and now yo can hear the sound it makes. 

My Movie 2-360p30 My Movie 1-360p30

When I rotate the stepper motor before calibration the sound you are hearing is on an other location on the slide

I also found out that the 3 rotations hiccups are on all stepper motors including y-as and extruder.

RE: Hiccup every 3 rotations on x-as and y-as

Factory reset?

RE: Hiccup every 3 rotations on x-as and y-as

Yes, First I tried a factory reset and that changed nothing after that I upgraded the firmware to the latest version and that also changed nothing.

I have no clue what to do next, because all stepper motors have that strange behaviour the next logical step will be the controller board but for some reason I can't imagine that it is a hardware failure because between the hiccups (mis steps) he is working very smootly.

RE: Hiccup every 3 rotations on x-as and y-as

I suspect (wild guess) issue with:

- generic electromagnetic interferences - from other electronics etc, or cables being too close to each other

- damaged electronics in the board (servo controllers)

- unstable power supply

Either way it may be good idea to talk to Prus Chat for help.

RE: Hiccup every 3 rotations on x-as and y-as

Thanks for all the help.

I ruled out this interference the rest I can't

I hope the Prus chat can help me out 🙂

RE: Hiccup every 3 rotations on x-as and y-as

I found out that the knocking sound of the stepper motor was in sync with the screen flashing.

I just disconnected the LCD screen and use the web-link to print my stuff, Now the printer really works fine, no knocking sound and a great printing result, and it is printing much faster.

It's only painful while (un)loading the filament. I need to connect the lcd screen for that.

I tried the Prusa chat to help me out, but they always force me to connect the screen and then try to help me with solving the knocking sound as if it's a mechanical problem.

I'm at a point that I just want to buy a new lcd screen because I'm not able to convince Prusa that it is no mechanical problem. But I'm not really 100% sure that the LCD screen is the causing the problem.

What do you all think?

RE: Hiccup every 3 rotations on x-as and y-as

I would start with the inspection of the lcd cable, maybe there is some damage to it ( though sometimes bit visible), and then moved to another lcd display if the cable is ok.

RE: Hiccup every 3 rotations on x-as and y-as

Thanks,

There was no damage visible on the flat-cable, but when I flatten it up the flashing was suddenly gone. 

When I was assembling the mini the instructions showed that you need to round up the flat cable in push it a bit in the aluminum profile on the bottom side.

At that point we found that a bad idea, but we just followed the instructions, I think at that point I damaged the cable.

 I will replace it with a new one. Thanks for all the help.

RE: Hiccup every 3 rotations on x-as and y-as

Well, you cable may be damaged... or not. Maybe the cable was too close to aluminium profile or adjacent cables were too close to each other, thus getting interference.

Try to run it with flat cable and just use a duct tape to attach it to the aluminium profile, or print special brackets for it and see how it goes over time. 
If the issues comes back maybe then buy a new cable?