First layers print OK but after 5mm or so it starts failing
 

First layers print OK but after 5mm or so it starts failing  

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muller.stephane
(@muller-stephane)
Active Member

Hi everyone,

I'm having a couple of issues with my Prusa and I can't wrap my head around them. 

The extruder makes a clicking noise, so I tried adjusting the tightening of the screw but the only time it stops is when the filament is completely loose. I don't get it... it's got to come from that right?

And then there's the print itself. First layers seem fine but after 5 mm or so the layers don't adhere to each other anymore until at some point the printer just prints in the air (see picture). I've tried playing around with Live Z-adjust because I thought the extruder was too far away, but again, no adjustment seemed to work... I even ended having the extruder so close to the plate that I have marks of the print that won't come off.

I don't get it... Does anyone have an idea of what I should do? What kind of adjustments do I need to make?

Many thanks for your help! 

Posted : 17/09/2020 3:54 pm
Peter M
(@peter-m-3)
Prominent Member

Looks like clogging, search forum for this.

Try printing petg, pla has more clogging with hot weather.

Posted : 19/09/2020 11:01 am
muller.stephane
(@muller-stephane)
Active Member

I've tried a couple of things now since my initial post.

I did a couple of cold pulls to unclog the nozzle, but it didn't change anything. Launched the same print with a different filament (still PLA though), same result. And then I thought I had a solid theory that explained everything: I had disassembled the head a couple of weeks back and thought that it could be possible that when I reassembled it the Z-adjustment was way off. If the nozzle was too close to the bed, the first layers would be pretty thin, the nozzle could get clogged somewhat and at a certain height the nozzle would be too far away from the print hence the spaghettis.

So I recalibrated the Z-axis using S3D calibration surfaces for PLA. The Z-adjustment was definitely off and now the first layer looks perfect (see picture). And yet... now the print fails even earlier than before (see picture as well)!!! Whyyyy???? God why?

What am I missing here? Please help... I'm getting real desperate here.

 

Posted : 23/09/2020 11:31 am
muller.stephane
(@muller-stephane)
Active Member

Any ideas? Anyone? 😟 

Posted : 29/09/2020 1:16 pm
Kolbi
(@kolbi)
Eminent Member

@muller-stephane,  being that your first few layers are good but then extrusion difficulties set it - this may be hotend temperature related. I'm thinking that your first few layers are just hot enough for good extrusion but then issues start once your slicer drops temp for the remaining layers.
I'd compare the temp settings and raise them a bit.

Cheers,
Kolbi

 
Posted : 29/09/2020 6:03 pm
GKMAKEIT
(@gkmakeit)
Estimable Member

@muller-stephane

Did this all start after you disassembled the head?

Have you been using that printer for a while and this problem just started?

Is it a new printer, give us a time line leading up to the problems.

Posted : 29/09/2020 8:29 pm
Peter M
(@peter-m-3)
Prominent Member

Did you do the rebuild good? Did you use thermal paste? Did you have before rebuild problems?

 

I would search for manuals for rebuild, prusa and e3d manual.

I would order a standard non prusa heatbreak, and replace the prusa heatbrake,

and then do a rebuild, and do this 100% correct.

After this you could add a extra 5 volt fan on the extruder, see thingiverse, to lower the temperature of the extruder motor, you could try without this.

If you print in a enclosure leave door open with pla prints.

 

Posted : 30/09/2020 9:32 am
muller.stephane
(@muller-stephane)
Active Member

Thanks for all your suggestions!!

@r-kolbi Will try this today and let you know how it goes.

@gkmakeit Yes, I'm afraid it started after I disassembled the head... I reassembled it with the sensor not well in place at first, which lead the Z calibration to go beyond what it should once. I corrected that, calibration went fine, but that's why I thought the live Z adjust was way off. In my head it explained everything... but now that I have a perfect first layer I have no clue what it could be.

Prior to that what I can tell you is that I've had the printer (already assembled) for a year. I have been using it regularly but not mass producing either. Just before I disassembled it, I needed to adjust the extruder idle screw because of some clicking noise. I don't know how but the grub screw of the extruder motor fell off and got stuck on the magnet. Which is why I disassembled the head in the first place.

@peter-m26 I think it's rebuild ok now, but since I still have problems I wonder... on the other hand I really don't see what could be off now. I checked the manual before reassembling it, everything is tight in place, no screws left.

Posted : 30/09/2020 9:48 am
GKMAKEIT
(@gkmakeit)
Estimable Member

@muller-stephane

After you completed the rebuild did you run a Z axis calibration not just a live Z first layer calibration?

Posted : 30/09/2020 2:52 pm
muller.stephane
(@muller-stephane)
Active Member

@gmakeit No I didn't, I just launched a new print and thought that the Z calibration before every print would do the trick... it doesn't?

Posted : 30/09/2020 3:08 pm
GKMAKEIT
(@gkmakeit)
Estimable Member

@muller-stephane

Nope.

On the printer display navigate to the "calibration" page and scroll down and you will see one called "calibration Z", but I would go through the "calibration XYZ" since you had the printer apart. See how that does and go from there, let us know the results.

After that you will need to do a live Z calibration.

This post was modified 2 months ago by GKMAKEIT
Posted : 30/09/2020 3:13 pm
muller.stephane
(@muller-stephane)
Active Member

@gkmakeit Alright! We're getting somewhere I think.

So I did the XYZ calibration. At the third spot it grabbed the paper so I lowered the PINDA a tiny bit and did the calibration again. After that I did the first layer calibration + the S3D calibration test and it looks good I'd say (see picture).

Then I printed the same little thingy and it actually managed to finish the print so yay! But some layers didn't adhere very well (I broke the little guy in two when taking it off) and the last layer is stringy.

What can I do next?

Posted : 30/09/2020 4:28 pm
GKMAKEIT
(@gkmakeit)
Estimable Member

@muller-stephane

Let's take a closer look at the first layer, are those ridges I'm seeing or just the color contrast? 

Are your Trapezoidal nuts tight?

Posted : 30/09/2020 4:34 pm
muller.stephane
(@muller-stephane)
Active Member

What do you mean by ridges? To me the layer looks alright. You mean the nozzle is a little too close to the bed? I can try lifting it a bit, see what happens.

What are trapezoidal nuts? Everything is tight from what I can tell.

Posted : 01/10/2020 2:09 pm
GKMAKEIT
(@gkmakeit)
Estimable Member

The top of the first layer, is it smooth or bumpy?

Theres...

Posted : 01/10/2020 2:34 pm
muller.stephane
(@muller-stephane)
Active Member

The top of the first layer is smooth. I've tried adjusting Z in both directions but I have just the right spot here, so it's not that I'm afraid.

Trapezoidal nuts are tight, nothing's wobbly...

Tried the print again, same result as last picture. This thing is driving me nuts.

Posted : 02/10/2020 1:54 pm
peter.k42
(@peter-k42)
Estimable Member

@muller-stephane

If you broke the little guy in two taking it off the build plate, turn the heat up.  You layer adhesion is poor.  More heat makes for better structural parts.

Posted : 02/10/2020 2:31 pm
GKMAKEIT
(@gkmakeit)
Estimable Member

Let's see how well the filament flows out of your nozzle.

Manually turn the nozzle on to the right temp for the filament you have loaded.

Remove the tensioner pulley screw(s).

Move up in Z around 150mm.

Once the nozzle is up to temperature grab the filament above the printer head and push it down at a nice consistent speed.

You should see a nice straight stream of coming out, if it curls or doesn't come out straight good change you have a partial clog. When you first start pushing it might stick to the nozzle, clear that and continue.  

Posted : 02/10/2020 3:21 pm
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