Problems with upper layers on first prints - What am I doing wrong?
 
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aomiles
(@aomiles)
Active Member
Problems with upper layers on first prints - What am I doing wrong?

I just put together my Prusa MK3s. It passed all the calibration tests, belt tests (readings for both are between 240 and 250) and I've adjusted the Z axis. I set it up to do the 7x7 mesh test as well. I also went and confirmed that all screws are tight.

I'm printing PLA on 215/60.

I started printing the prusa logo and had large glops of PLA on the top layer. I slowed the flow to 90 and lowered my Z axis from -.860 to -.910. This took care of the glops, but the top layer fill on the "S" and"U" doesn't meet the outline at the very bottom. Picture is attached.

Then I printed a Benchy and it seemed to be working fine until the last 30 minutes when I looked over and I had spaghetti everywhere and the boat had moved off to the side. I'm not sure whether it slipped off the mat and then spaghetti'd or if the spaghetti pushed it away. It was solidly in place for the first 90 minutes.

I'm guessing that I can fix the fill issue on the logo with some setting. But what is going on with the Benchy? Is that because of the flow, not sticking to the mat, or the Z axis being too high? Any help would be appreciated.

Thanks.

Best Answer by Peter M:

Check the whole printer on loose bolts , screws, grub screws.

Check extruder is not to loose.

Pull the power on the printer, move all axis by hand, check if you feel bad spots wen moving.

Clean all rods, and put oil on them.

Check belts if they are not hitting the side, move x-axis left to right, and check if belt is hitting the side.

Make a movie wen print fails.

This topic was modified 1 year ago by aomiles
Posted : 02/09/2020 11:35 pm
aomiles
(@aomiles)
Active Member
Topic starter answered:
RE: Problems with upper layers on first prints - What am I doing wrong?

Also, I am cleaning the powder coated steel with 91% IPA before every print. I also let it cool before cleaning. 

Posted : 02/09/2020 11:49 pm
jsw
 jsw
(@jsw)
Noble Member
RE: Problems with upper layers on first prints - What am I doing wrong?

What does your Z calibration print (either the internal one or one of those 3x3 test prints or something) look like?

Posted : 03/09/2020 5:50 am
aomiles
(@aomiles)
Active Member
Topic starter answered:
RE: Problems with upper layers on first prints - What am I doing wrong?

so I found a really helpful post about using the 3x3 square for the z axis calibration. It turns out I was way to high (about .15 off). That seems to have solved the spaghetti issue. But my latest one (pic attached) now has a weird defect that might be layer shifting? My belts are both about 247 so they should be fine. I also checked all the screws. Or is this something else? It looks like it just went to an angle for a few minutes and then snapped back.

 

 

Posted : 03/09/2020 5:55 am
jsw
 jsw
(@jsw)
Noble Member
RE: Problems with upper layers on first prints - What am I doing wrong?

That layer shift and shift-back looks like a mechanical issue and most likely with the belt or the pulley on a stepper motor being loose.  Be sure that the 'grub screws' are correctly tightened.

I can't tell from the photos which way your Boaty McBoatface is facing, so check the things on the axis of that shift.

I do not have that much faith in the belt numbers being accurate.  I think that the test of plucking the belt is better, and it should vibrate like a bass note instead of flopping around.  Also, you can hold the shafts of the stepper motors still with pliers and try to move either the extruder or the heat bed.  There should be no significant 'play' in the mechanical action of either axis.

Posted : 03/09/2020 6:07 am
aomiles
(@aomiles)
Active Member
Topic starter answered:
RE: Problems with upper layers on first prints - What am I doing wrong?

I have done the pliers test and there is no play. I watched a YouTube video of someone showing the tension of a prebuilt MK3s and mine appeared to be similar. Is there any way besides the belt test to actually measure the tension?

Also, benchy was printed at a 45 degree angle facing the front left corner (as you face it). I believe it was the x axis.

The other weird thing is that low prints seem to be fine. I printed a low turtle and the Batman symbol and they came out great.

This post was modified 1 year ago by aomiles
Posted : 03/09/2020 6:12 am
Peter M
(@peter-m)
Noble Member
RE: Problems with upper layers on first prints - What am I doing wrong?

Check the whole printer on loose bolts , screws, grub screws.

Check extruder is not to loose.

Pull the power on the printer, move all axis by hand, check if you feel bad spots wen moving.

Clean all rods, and put oil on them.

Check belts if they are not hitting the side, move x-axis left to right, and check if belt is hitting the side.

Make a movie wen print fails.

Posted : 03/09/2020 10:26 am
aomiles
(@aomiles)
Active Member
Topic starter answered:
RE: Problems with upper layers on first prints - What am I doing wrong?

So I found the issue. The Z axis was slightly off and I printed a 3x3 square to fix it. Then I found that one of the Y axis grub screws was loose. Now everything is printing great! Thank you for the help.

Posted : 04/09/2020 1:56 am
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