What kind of print defect is this?

Have an issue you can't figure out on your own?
Stefan
Posts: 223
Joined: Thu Jun 15, 2017 12:46 am

What kind of print defect is this?

Post by Stefan » Mon Jul 31, 2017 7:56 pm

Hi Guys,

I'm trying to print a project enclosure. I've made it three times and the same defect appears in the exact same location.
  • Hatchbox PLA Grey
  • Extruder temp: 190-200 bumped the temp up each time
  • Bed temp: 60
  • Sliced on Cura 2.6: 0.2 thickness, 3 shells, no support, cooling fan on
Oddly, when I printed the model rotated 180 degrees, I got a similar defect slightly lower on a plain wall at the same spot relative to the printer. Using Slic3r the defect was not produced (though it made a generally poorer print).
IMG_0485.jpg
IMG_0485.jpg (421.69 KiB) Viewed 1822 times
Any ideas?

Thanks,
Stefan

Peter Bermingham
Posts: 13
Joined: Thu Jul 06, 2017 6:00 pm
Location: Warracknabeal Victoria Australia
Contact:

Re: What kind of print defect is this?

Post by Peter Bermingham » Sat Aug 05, 2017 1:21 pm

I know you said when you use slic3r didn't do the defect, but I've got a feeling it May have something to do with the printer more so than the slicer.
I would try printing a A wall, around the size (height and width) of where the defect is place it on the same place on the printer bed to see what happens, at least if it works fine it takes the printer out of the equation .

User avatar
PauloMateiro
Posts: 11
Joined: Wed May 24, 2017 1:33 pm

Re: What kind of print defect is this?

Post by PauloMateiro » Mon Aug 14, 2017 10:38 pm

Seems the same problem I have with horizontal holes/slits near the edge of the print. As far as I gathered this is related to slicer settings rather than printer hardware. I've seen it in a few places and even on a 3d printed part featured on a Youtube channel - non 3d printing related, BTW.

Theory is that the retraction for the gap "unprimes" the extruder and it takes a few milliliters for the extruder to re-prime itself again. Right now I'm playing with retraction settings and the "Retraction Extra Prime Amount" setting in Cura. Will keep you all posted.

Stefan
Posts: 223
Joined: Thu Jun 15, 2017 12:46 am

Re: What kind of print defect is this?

Post by Stefan » Tue Aug 15, 2017 5:01 am

Hi PauloMateiro,

I've come to a similar conclusion. Also note that the seam at that height is right at that corner. I wonder if significantly slowing down the print would help.

-S

User avatar
PauloMateiro
Posts: 11
Joined: Wed May 24, 2017 1:33 pm

Re: What kind of print defect is this?

Post by PauloMateiro » Tue Aug 15, 2017 10:27 am

Hello, Stefan,

I really don't know if slowing down the print would significantly help. For what happened to me yesterday... I have to say it wouldn't help much. You see, out of pure frustration I started a print at about 60 mm/s - usually I print at 40 to 45, even though I think I can go up to 80 or 90. I did change the retraction settings in Cura and even though the speed was 30% higher than usual, I think that those artifacts were smaller.

I will have to double check and print something else today, but for now I would suggest you to play around with those settings. Right now I have:

. 0.8 mm retraction distance;
. 30 mm/s retraction speed;
. 30 mm/s retraction prime speed;
. 0.64 mm3 Retraction Extra Prime Amount;
. 0.8 mm retraction minimum travel;

and also enabled

. Z Hop When Retracted:
. Z Hop Only Over Printed Parts;

and

. 0.075 mm Z Hop Height.

Bear in mind that this is for a chinesium grade printer with a bodged Mk 7/8 extruder.

Regards,

Paulo

User avatar
PauloMateiro
Posts: 11
Joined: Wed May 24, 2017 1:33 pm

Re: What kind of print defect is this?

Post by PauloMateiro » Thu Aug 17, 2017 12:47 pm

OK, some news.

My latest prints show some improvement with the "Extra Prime Ammount" setting. It seems that my bodged extruder "oozes" as soon as it is turned of and so it fails to extrude just after it retracts.

Let me see if later today I can get some pictures.

Stefan
Posts: 223
Joined: Thu Jun 15, 2017 12:46 am

Re: What kind of print defect is this?

Post by Stefan » Thu Aug 17, 2017 9:56 pm

Sounds great, Paulo. Look forward to seeing what you came up with.

-S

User avatar
PauloMateiro
Posts: 11
Joined: Wed May 24, 2017 1:33 pm

Re: What kind of print defect is this?

Post by PauloMateiro » Fri Aug 18, 2017 11:27 am

OK, finally managed to get some pictures - and host them.

Here is one of the defects:

Image

It seems to underextrude after the hole.

Another part, this one with the "Extra Prime Amount":

Image

That seems to improve thing a bit. :D

I will also try to design a part this weekend to further test this, specially with thinner walls, but for now I'm pleased with the progress.

Stefan
Posts: 223
Joined: Thu Jun 15, 2017 12:46 am

Re: What kind of print defect is this?

Post by Stefan » Sat Aug 19, 2017 4:04 am

The gaps you are showing appear to be much shorter; mine are about 1.5cm. Do you still think that this might get be the same problem?

-S

User avatar
PauloMateiro
Posts: 11
Joined: Wed May 24, 2017 1:33 pm

Re: What kind of print defect is this?

Post by PauloMateiro » Sat Aug 19, 2017 10:28 am

I think so. I'm just now printing a small test part and will post the results later today.

Post Reply

Who is online

Users browsing this forum: No registered users and 4 guests