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Advice needed - Too many issues to list them all  

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DoubleX
(@doublex)
Active Member
Advice needed - Too many issues to list them all

Hello,

Let's get to it straight.

The issues:

- Y axis belt is loose despites numbers being high. Also motor is pretty noisy. (Tension number: 255-260)

Support answer: Flash to another firmware... But I got an MK3S+ so I got only one other possibility, and the numbers were pretty identical on the previous version.

- X axis belt is tight when the extruder is in the middle, but looks pretty loose otherwise. (Tension number: 245-250)

- Bed Visualizer using the numbers from the SuperPINDA reports a tilted horizontal flat plane, but using a paper folded twice it's pretty much leveled within +/- 0.08mm or so.

From left to right, the difference is 0.7-0.8mm, but how am I supposed to interpret these numbers? How comes the PINDA report it's off by 0.6mm on the right side? There isn't 0.6mm of space between it and the steel bed.

- The Live Adjust Z will lose itself upon powering off the printer

Might be related to bad bearings, see my note about it below.

- The X axis tends to bind at the very last end of it, opposite of the motor, it already removed a tiny tiny small patch of the coating (can feel it with the nail or see it when looking very closely).

I was suspecting a bent smooth rods, but rolling on a flat surface looks alright, one is maybe a littl' less round than the other maybe. But then I suspect more the printed parts to actually cause the bind. 

I ended up dissasembling the X axis and the extruder along with it, and taking the opportunity to pack the bearings with lithium grease.

Turns out, there are two bad bearings on the Z axis, trying to slide the smooth rods by hand is actually pretty hard despites the bearing freshly packed and the bearings won't slide by themselves at all.

Moreover one of the bad bearing is actually doing something funny: When pushing it a bit to the top it goes back down a bit, just like if it has backlash, or maybe is that actually the famous backlash?

Now it's been 2 months since I had the printer and couldn't really print much because of the bed flatness issue.

The last part I replaced was the Y carriage, and in the meantime I took the opportunity to reduce the rocking of the frame from approx 0.3mm to 0.1mm (can't do better). I didn't try to print anything with it after that.

As I then started to look at the belts issue, the motors were so noisy and highly pitched I had to look at that, printing would have been unbearable.

Not trying to bash Prusa support here, I think it's awesome they already sent me two times replacement pieces. I'm also pretty confident in them that they will once again when I can provide them the reason to do so.

If I wasn't short on funds, I would be buying a second so at least I'd have something else to do while waiting for replacement parts.

I'm asking for some suggestions here to look about so I can properly diagnose and fix what needs to be fixed to get it right.

Thanks.

Posted : 31/01/2021 2:45 pm
Dan Rogers
(@dan-rogers)
Noble Member
RE: Advice needed - Too many issues to list them all

Long list, here's some practical easy ones

If you can still print PETG, do print the pattern for the belt tightness gauge.  

For motor noise - assuming it's normal noise, try a squash ball feet upgrade.  Some folks might recommend stepper dampers - but to me that's a trade-off in accuracy, hard to say.

Posted : 02/02/2021 7:23 pm
DoubleX
(@doublex)
Active Member
Topic starter answered:
RE: Advice needed - Too many issues to list them all

Oh interesting. I can print it since it's a pretty small part.

Motor noise isn't really a problem, I mean I can bear with it but that's what I meant, it's probably not right and translating what I'd call a sticky axis since the X axis is pretty hard to move due to the out of parallelism printed parts.

Anyway the third RMA is on the way, I'm being sent off a new magnetic bed along with a new SuperPINDA, new X axis printed parts and new bearings. Kudos to the support for that.

It's a huge list, I was pretty unlucky on this kit since I had no less than 5 bad bearings or so, considering they are Misumi too...

Posted : 02/02/2021 7:30 pm
This_Dude_Jay
(@this_dude_jay)
Active Member
RE: Advice needed - Too many issues to list them all

Is the difference of 0,7-0,8mm from left to right consistent for front, center and rear row alike or just the max. distance for instance between front left and rear right point?

And with Live Adjust Z losing itself you mean the value is deleted or the value isn't correct anymore for the perfect first layer?

Posted : 02/02/2021 8:12 pm
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