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Can't pass calibration very sad....  

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McShannon
(@mcshannon)
New Member
Can't pass calibration very sad....

I got the printer and got it assembled before Christmas, but could not pass calibration. I got busy and let it sit. Trying again it is doing the same thing I have made some videos and posted them to YouTube. I have tried adjusting the senor height and that has not helped yet.  It is checking the 4 points it does all 4 then fails. I think early before some tweaking it did not make it past the first or second.

 

I have also posted on FB group. Help would be great. Willing to do more videos if anyone in the Dallas area ( I am in Greenville TX)  willing to pack it up and meet up. 

 

 

 

Posted : 15/05/2021 2:59 pm
ssill2
(@ssill2)
Prominent Member
RE: Can't pass calibration very sad....

yeah this is the reason I bought both my printers assembled lol.   I was afraid I'd run into similar issues.  I'm sure someone on here can help you get sorted though.

Posted : 15/05/2021 5:44 pm
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(@)
Illustrious Member
RE: Can't pass calibration very sad....
Posted by: @mcshannon

I got the printer and got it assembled before Christmas,

Was the nozzle actually in contact with the bed heater when you placed the cable tie under it? 

Posted : 15/05/2021 6:07 pm
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(@)
Illustrious Member
RE: Can't pass calibration very sad....

https://help.prusa3d.com/en/article/xyz-calibration-mk3-and-mk3s_112351

and

https://help.prusa3d.com/en/article/xyz-calibration-error-messages-mk3-mk3s-mk3s_112340

Hint at the PINDA height being the problem. Not all PINDA's are created equally - some are simply less sensitive than others and need to be installed lower than the instructions call for. So if the nozzle was in contact with the bed when you set the PINDA height, try lowering it a half mm.

Another check I'd do is when it fails the cal, manually run the extruder around the bed to check the PINDA-bed spacing remains the same at the center and four corners. If for whatever reason the bed is warped and cal points are physically lower than expected, you'll also get a fail. 

Posted : 15/05/2021 6:21 pm
McShannon
(@mcshannon)
New Member
Topic starter answered:
RE: Can't pass calibration very sad....

Meeting someone at 3pm to look at it with me. Hopefully with suggestions and his help will get it going.

Posted : 15/05/2021 6:45 pm
ssill2
(@ssill2)
Prominent Member
RE: Can't pass calibration very sad....

nice.  that's super nice of them.  Hope it works out!

Posted : 15/05/2021 8:07 pm
McShannon
(@mcshannon)
New Member
Topic starter answered:
RE: Can't pass calibration very sad....

Update not done but think we made progress

 

He ran some of the other calibrations, and there was an issue with one belt and fixed that by tightening. 

He ran a test that checked the 9 points and the first time it failed on the 4th, then we adjusted the Pinda height and it was able to pass that test. While running that test we observed that the bed is not level, it got a lot closer on the right side before stopping than on the left.

 

We think right now the failure is that the bed is higher on the right side than the left, and that is the next thing going to work on.

Posted : 15/05/2021 10:52 pm
ssill2
(@ssill2)
Prominent Member
RE: Can't pass calibration very sad....

@mcshannon

Nice!  Progress

Posted : 15/05/2021 11:00 pm
blauzahn
(@blauzahn)
Estimable Member
RE: Can't pass calibration very sad....

@mcshannon

you are on the right track.

 

Please be aware that after moving the printer it is recommended to redo the calibration. The frame is not infinitely strong. It is also recommended to carry the printer only at the middle of the upper frame plate (the one with the large "prusa" engraving). If you transport the printer in a car, please put sth. soft beneath it.

 

https://help.prusa3d.com/en/guide/2-y-axis-assembly_165795
step 10 y-axis: geometry check

 

How well did that work out? Especially the front right side comes up easily when you (over-)tighten the screws. The meshbed leveling can compensate for an uneven bed quite well but can do this understandably only for a limited height range.

 

It is therefore helpful, when the frame is assembled, to do that on the most even plane you can get. Eg. a ceran plate of a kitchen stove might be feasible for that. If you even can get access to a straightening plate in a machine shop, go for it. If the printer is already assembled, please take care of the cables. Maybe using some feather-keys as quite precise distance pieces. I stripped my working printer completely down and reassembled it over Christmas in order to have it even better leveled and perpendicular in z versus xy.

 

Do you have some measuring tools available (calliper, feeler gauge, straight edge, steel square for toolmakers, dial gauge, spirit etc.) or can you borrow them? A mason's spirit might not be up to the job.

 

The x-axis gets its level (left versus right) by ramming both z-axis into the upper ends during XYZ-Calibration. This determines the distances to the bed when  traversing from left to right. The frame plate is machined quite precisely and its outer and inner shape can serve as references. x-axis rods and bed should be parallel to it. For the bed that means that the two rods of the y-axis have to be at the same height, level and parallel. If the printer sits on a good assembly plane you can measure the height of each rod at each end e.g. with a calliper. Since there is hardly any height adjustment available on the y-rod holders, a well assembled frame is important.

 

Apart from passing the calibration, a well assembled printer helps a lot to get the all essential first layer of every print right. So, putting some effort into the assembly will pay off. Take your time for that.

 

Make sure that all axes have correctly aligned linear bearings and can be moved by hand smoothly and as easily as possible. Please be aware, that the bearings come only with anti corrosion oil and definitely have to be cleaned and greased well but not overly. The small tube that came  with the printer indicates what amount is considered enough for the whole printer. I grease my bearings very carefully with a tooth pick.

 

You are probably aware of this prusa site:

https://help.prusa3d.com/en/article/mesh-bed-leveling_112163

 

If your XYZ-Calibration works right now, leave the PINDA position as it is.  In case you want to readjust it and have somebody who can print something for you, you might use this distance tool for the PINDA adjustment instead of a zip tie:

https://www.prusaprinters.org/prints/57049-lehre-fur-pindaspinda
(if possible, to be printed with 0.1mm layer height)

 

For the Pinda of the MK3S, the nominal distance between nozzle and PINDA is 0.8mm. The nozzle has to be put in contact with the lower surface,  the PINDA onto the one marked 0.8. The topmost surface is for the larger distance of 1.5mm for the newer Super-PINDA. But as far as I have seen in your videos, you have an MK3S with the PINDA, right? The tool gives you a good initial height. As Tim already stated, if necessary, lower it a bit.

 

Once your meshbed leveling is working, you might want to inspect the measured bed heights. This can be done via USB with an old fashioned serial terminal program via a laptop or PC. Many use Pronterface/Printrun for that. After connecting to the printer, you already should see it sending messages back onto the console. The meshbed leveling can be started by entering the G-Code G80. The results are written out when issuing the G-Code G81. Another way to do so is by using a popular Raspberry Pi mini computer using Octopi and a plugin for the meshbed levling.

 

Again, if somebody can print something for you, this gauge might be helpful as well in order to verify the belt tension:

https://www.prusaprinters.org/prints/46639-tension-meter-for-the-gt2-belts-of-i3-mk3s-or-prus

 

Please be patient. Do not give up.

 

Have a nice day

 

Greetings from Germany.

Posted : 16/05/2021 6:16 am
McShannon
(@mcshannon)
New Member
Topic starter answered:
RE: Can't pass calibration very sad....

@tim-2

dealing with bed uneven/warped is what we are working on now

Posted : 16/05/2021 3:09 pm
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(@)
Illustrious Member
RE: Can't pass calibration very sad....

@mcshannon

There really isn't anything to do to adjust bed level. That's like chasing rainbows.

If bed level is off enough it corrupts the XYZ calibration, you need to take the bed apart, and work on leveling the frame -- and that is the only way to fix the rods being uneven. And it's uneven rods that cause the bed to be askew.

Posted : 16/05/2021 4:31 pm
Dan Rogers
(@dan-rogers)
Prominent Member
RE: Can't pass calibration very sad....

Does sound like a bed assembly issue.  The manual has steps to make sure the frame is square - that is where I'd suggest you start.  Use a square as you cannot eyeball squareness.  Needs to be square in all 3 dimensions before you start messing with anything else.  Once square, see if that corrected the issue - and if not, on to the rails that hold the bed.  Are the holders mounted properly.   Using a level, you should make sure your frame (now that it is square) is level.  If it is not, level the surface you have it sitting on.  Be sure to check level in both X and Y and plumb in Z.

 

 

 

 

Posted : 17/05/2021 3:59 pm
cwbullet
(@cwbullet)
Illustrious Member
RE: Can't pass calibration very sad....

@mcshannon

Beds are usually level enough if they were assembled correctly.  

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Chuck H
3D Printer Review Blog...
Posted : 17/05/2021 6:52 pm
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