Strange alterations in printquality at the first 4-5 mm hight

[Harry Plotter 3]

Hi, I am printing objects now for a couple of month and have advanced quite a bit. First I used sketchup then I trained on spark mechanical.

 

Now it´s running fine but since the update of the firmware of Cura and or the new upgrade of the printer there seems to be a bug and I can not see where the problem is.

 

Some prints are not affected. But especcially when I am printing in conjunciton with PVA the objects get distorted or somewhat unpricise (see fotos).

 

Can I do a firmware reset, or can I reset Cura to original settings and retry? Or maybe you know what this is all about and give me some hints in what can cause this. Especially the foto with the comparison print (strange print next to normal print). There you will see a humongous difference on how the same .stl file was and is printed... I did not draw or see in the .stl - File that theere should be a difference between the outer wall and the 4 feet that rise upwards... it should have come out like in the first print. Maybe my printer uses up all of my Gin... do printers can get drunken lately ;O)

 

I am somewhat clueless.

 

Maybe one of you had similar problems and found a solution or has a hint for me as to where I should look for.

 

Greetings

 

 

Daniel

[gr5 2,172]

I'm pretty sure there are 4 different issues here.  So here's what might happen - we'll start focusing on one issue and the other issues will be forgotten.  so I recommend if that happens you start a new topic and don't keep posting here.  The new topic(s) should focus on only one issue.

 

Let's start with the black part.

 

In the first picture of the black part the photo is to blurry to see what you are talking about - please improve that.

 

In the last picture that looks like some serious print error.  Was that present in cura slice view?  Always check slice view before printing.  Well that error does NOT look like an ultimaker 2 or 3.  It looks like play/backlash.  Caused typically by loose belts.  I guess I need to know what printer this is and if it's the X or Y axis (because some printers unlike UM are very different for the 2 axes).  Please read about "backlash" perhaps on wikipedia which has a good article and think about "play".  Try pushing the nozzle (with printer off and cold - dont' burn your fingers) and feel how much you can move the nozzle without any steppers moving.  Also check friction of X and Y axis.  Does your printer use belts?  They might be too loose (causing play directly) or too tight (causing friction which increases backlash).

 

Regarding "the bottom 4-5mm in height".  If you have a heated bed you will see differences in the bottom 4mm or so because the air is warmer.  On UM printers I recommend 60C (no hotter, no colder).  70C will make the problems much worse.  Fans will make the bottom layers a bit better and also printing cooler (try dropping print temp by 10C) will help but the best fix is usually to fix this in the CAD.  If walls are printing/moving inwards you can fix this in CAD by moving them outward again.

 

I think on some of your issues you had overhang issues maybe?  Not sure - need better photos please.  But note that 3d printers don't do as well on overhangs and the fix is usually first and foremost MORE FAN (add more fans to your printer - make sure they are at 100%).  This fix only works for PLA by the way.  The other fix is to print slower and cooler.

[Harry Plotter 3]

Hi gr5,

 

thank you for your reply. I will check the "belt issue" for sure! I am using a UM3 Exd. and as I am already printing for some 6 month+ I supposed it was not a hardware-based problem. Nor was there a problem with overhangs. The main problems was that the objects did come out in another shape than Cura slices them (see comparison of the black objects) Another problem was that the objects printed were not perfectly round anymore (see the "ripped off" curve from the syringe and the stamp...

 

Right now this issue seems to be solved. I tell you what I did. First I reinstalled CURA because there was an update beween the last and the acutal print. Every time I checked the slice-view and there was no difference in beween the print-views. But as you saw the black parts came out way differently, so I suppose it was Cura itself. Anyhow I completely reseted Cura and also the UM3. For now it seems to work fine again. Maybe there was still another issue with the PVA-layers in conjunciton with the overhangs because the overhangs I usually print with support every time. When the nozzle with th PVA behaves strange (what kind of happens sometimes if the nozzle is not 100% clean) it tends to string and probably that is what left the traces on the ball. Another thing I recognized is that with the experimental check "use adaptive layers" I  can not print in conjunction with PVA. This will fail 90% of all times so I quit using this. Sometimes this will save alot of time but it won´t work in conjunction with PVA nor does it work with the PVA alone. This cloggs and rips off the material everytime and no overhangs will survive after that.

 

Anyhow I will do some research on the belt issue but I hope that it will not happen again and that it was a Cura - realted issue ( I´using Cura 3.2.1 right now b.t.w).

 

Greetings

 

 

Daniel