Loses the 0 point of the X axis  

Re: Loses the 0 point of the X axis

Have you got any help from the Prusa Support?
Looks to me like the printer detects crash all the time.
At 2:38 it tries to home and hits something. That's why the x-0 position is off. You can hear a click. Sounds to me like something mechanical is not right.

Re: Loses the 0 point of the X axis

Good evening nikolai
yes I spent hours with support by chat and email.
By Chat with three interlocutors, none has provided a solution. Marina made me reverse the connections of engines X and Y and told me that if the problems continued, she would send me a new engine X, "...It is no problem. the MMU, where it is, the X axis is defective and I can send you a replacement" but after having confirmed to him that the problem persists, no more news.
With others we checked the tension of the belts. the values ​​that are given to me are contradictory for X 240 or 280, then more news ...
Do you know how to update the belt tension values ​​after adjustment? Wisard? self test?
By mail [email protected] I was asked to check the motor resistance, then more news ...
Personally I do not hear a click when the printing of the Prusa logo stops. If I do a self home at this time, the stripper returns to 0 on Y but not on X.
I managed after mounting the Kit to print objects correctly ...
It is certain there is a problem but it is difficult to know which one and even less with the support for 12 days ...
That's why I'm asking for the forum.
I'm desperate...

Re: Loses the 0 point of the X axis

Try to turn the printer off and move the extruder in X- direction by hand the whole way through back and forth. There should be no big resistance. Everything need to run very smooth. Move the bed the whole way through up and down, so you get a feeling how it should run.
Maybe there is something wrong with the bearings or any assembly issue. But I can clearly hear a "clock" sound even in the second homing procedure.

You should also try to turn the crash detection off.

Re: Loses the 0 point of the X axis

I am surprised that Prusa has not simply replaced your printer as it is an assembled unit with full Warranty in your place I would push for replacement

Re: Loses the 0 point of the X axis

Try to turn the printer off and move the extruder in X- direction by hand the whole way through back and forth. There should be no big resistance. Everything need to run very smooth. Move the bed the whole way through up and down, so you get a feeling how it should run.
Maybe there is something wrong with the bearings or any assembly issue. But I can clearly hear a "clock" sound even in the second homing procedure.

You should also try to turn the crash detection off.

Hello Nikolai
And thank you for your suggestions.
Both axes move freely and without hard point.
I was very attentive editing (example [ https://photos.app.goo.gl/o11MwEq74vLPWWgW8 ) which seems to me confirmed by a perfect operation of the printer for 4 days. In addition the support excluded an error of assembly and parralelism to the extent that the wisard fisification of the MK3 specifies that the test of parralelism is ok.

On support advice, I disabled the crash detection but it does not change anything.
Really I do not understand what is happening and I am abandoned by the support PRUSA which is very disappointing of the brand.
Good day to you

Re: Loses the 0 point of the X axis

I am surprised that Prusa has not simply replaced your printer as it is an assembled unit with full Warranty in your place I would push for replacement

Hello
In fact it is a KIT that I assembled. Although the printer has worked perfectly for 4 days, there is a problem that the support does not identify, which seems understandable because it does not really try to understand it.
Have a good day

Re: Loses the 0 point of the X axis

I can't get your videos to play back, but from the still images I see the left x-end (motor mount) is badly fractured. The x-motor tensioning bolt has been advanced too far and cracked the mount. That part needs to be reprinted and replaced.

Re: Loses the 0 point of the X axis

I can't get your videos to play back, but from the still images I see the left x-end (motor mount) is badly fractured. The x-motor tensioning bolt has been advanced too far and cracked the mount. That part needs to be reprinted and replaced.

Hello Guy
Yes you are right.
It's my fault. However this case has occurred after the point loss problem on X appears. The support asked me to resize the X belt, which was worth 238, at 280 (another support interlocutor had told me that 240 was the right value and that 238 had to work).

I had downloaded the files for spare parts when needed. But for now I can not print anything ...

Have a good day

Re: Loses the 0 point of the X axis

Losing X is most likely stemming from two things sources.

1. Loose pulley grub screws on x-motor.
Make certain grub screw engages flat portion of shaft. Both should be tight, but not cutting into shaft.

2. Wrong belt tension (either too loose OR too tight)

Belt tension adjustment is unfortunately very limited in stock Mk3 design. You must get the belt teeth within one notch of correct in the x-carriage. The adjuster only has about one belt tooth range of adjustment. Also, one must remove the entire back of the carriage to adjust belt tooth position. That means undoing all the cables from back of extruder.

Loosen all the x-motor bolts
Back the x-motor tension bolt back to no longer making contact with the motor bolt.
Undo wire bundle at back of extruder. Yes this is a pain and why I would switch to an alternative x-back once you get the printer running.
Adjust belt tooth position so the belt is almost tight enough.
How tight is tight enough? It is very easy to pinch the belt top and bottom together, but definitely harder if you angle the motor outward.
Put the back of x-carriage and wiring bundle back together
Adjust x-motor tension and secure motor.

Ignore the support menu slackness figure. That can ges you into too much belt tension if you blindly target 240's. Just ignore it. Instead, set tension by pressing center of belt with a 10 cm long rod. As you begin pressing on belt, you feel it initially move with very little change in resistance. Press a bit further and you notice the resistance increase more dramatically. That is the start of the belt stretching. You want tension set so that change in resistance occurs at about 5 mm belt deflection.

Attempt xyz calibration.

Re: Loses the 0 point of the X axis

Losing X is most likely stemming from two things sources.

1. Loose pulley grub screws on x-motor.
Make certain grub screw engages flat portion of shaft. Both should be tight, but not cutting into shaft.

2. Wrong belt tension (either too loose OR too tight)

Belt tension adjustment is unfortunately very limited in stock Mk3 design. You must get the belt teeth within one notch of correct in the x-carriage. The adjuster only has about one belt tooth range of adjustment. Also, one must remove the entire back of the carriage to adjust belt tooth position. That means undoing all the cables from back of extruder.

Loosen all the x-motor bolts
Back the x-motor tension bolt back to no longer making contact with the motor bolt.
Undo wire bundle at back of extruder. Yes this is a pain and why I would switch to an alternative x-back once you get the printer running.
Adjust belt tooth position so the belt is almost tight enough.
How tight is tight enough? It is very easy to pinch the belt top and bottom together, but definitely harder if you angle the motor outward.
Put the back of x-carriage and wiring bundle back together
Adjust x-motor tension and secure motor.

Ignore the support menu slackness figure. That can ges you into too much belt tension if you blindly target 240's. Just ignore it. Instead, set tension by pressing center of belt with a 10 cm long rod. As you begin pressing on belt, you feel it initially move with very little change in resistance. Press a bit further and you notice the resistance increase more dramatically. That is the start of the belt stretching. You want tension set so that change in resistance occurs at about 5 mm belt deflection.

Attempt xyz calibration.

Thank you for your time GUY

1 - I am cetain to have well mounted the screws on the flat part of the axis of the engine.

2 - Tensing the X belt and as you could not see the video of google photo, I reloaded a video of the belt on youtube that I had made for the support last Saturday. Are you coming to watch it? What do you think?
I could adjust depending on your answer.

I agree with you on the menu support slackness figure. But it gives however a quantified information of tenssion. Do you know how this menu can update its measurements?

thank you so much

Re: Loses the 0 point of the X axis > ball bearing Fail

Hello
I thank you all for your answers

One of the answers (THTX to nikolai.r) suggested to check the correct displacement of the extruder on its axis.
In the state, mounted, nothing to report, it moved correctly without hard point.

However I took it apart to disconnect the belt and check more precisely. This is where I discovered a very hard point that completely blocked the extruder on the movement from right to left. It took me a long time to find out what was going on and finally figured out that by unscrew slightly the back plate of the extruder the blockage was no longer occurring. Finally it is the ball bearing that blocked the return to the left.
[Img] https://photos.app.goo.gl/WKmB4g2nGiZaEpv86 [/ img].

I totally disassembled the X axis, and found that the bearing was defective, it was missing 2 or 3 balls [img] https://photos.app.goo.gl/HPjthFAhj2FobEwh6 [/ img].

By testing it very scientifically: D [url] https://photos.app.goo.gl/NmKiTyF6UFPjA5AJ8 [/ url] I told myself that it could only be the cause of my problem.
And indeed, I inverted with a Z axis that has more power since moving is not the metal screws and not a belt. No more blocking worries than I had for a loss of bearings. So, I tested all my bearings and I have 2 which lacks balls.

However, I contacted the support again (at 1am) and they sent me 10 new bearings, I had UPS support the next morning 9am.
In short, I lost three weeks looking for a soft anomaly for a simple ride that could not do its job. I have long yell on the support that could not find an explanation, but in fact it was not obvious. At the same time they do not seem to be very confident with their supplier because for two balls bearings, they send me 10 to be sure I can find that work perfectly.

I tell myself that this experience can be useful to other MK3 kit assemblers.
Now I print and well.
Somehow I do not regret it, it allowed me to meet you.
Good day to you and thank you again for your time.

Re: Loses the 0 point of the X axis

Hello Emmanuel,

The ball bearings can also fall out during assembly or just be slightly damaged. It happened to me once but luckily I saw it and had couple replacements on hand. This is something you also sometimes realise during operation.
Anyway I'm glad you found the issue and printing again!

Happy Printing,
Nikolai