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DoRayEgon

Blobby prints, bad infill and detaching supports.

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As per the title, I'm having some issues with a print that I've been trying to do for weeks now.

I'm using an Ultimaker 3+ and printing with Ultimaker ABS. I've got the latest firmware and Cura version.

The first few prints I did were working fine but it seems to have gotten progressively worse. The biggest issue seems to be loads of blobby parts to the outer wall of the print. The infill also come out really patchy and often doesn't print at all. Finally, the supports seem to lose adhesion to the main part of the model and detach mid-print.

I've tried cleaning the print core, autolevelling and have recalibrated the xy offset. Nothing seems to make a difference.

I'm getting the same result no matter whether I print with 0.04mm, 0.1mm or 0.15mm layer height. I'm generally printing at 230 degrees people to head and 80 degree build plate. My print speed varies from 45-60mm/s depending on layer height.

I'm a bit new to all this and I'm at a bit of a loss. The printer was performing great but has just gotten worse and I don't know why. At some stage I updated the firmware and Cura software and things seem to have gotten worse after that, but that could just be my imagination.

Here's a photo of the bad infill:

https://www.dropbox.com/s/4pr9r7fbuw01s6w/IMG_6789_zpsqlgxulgt.JPG?dl=0

The inner most circle is supposed to have 20% infill.

Here is the blobby walls:

https://www.dropbox.com/s/7am6ksfp1998v0i/IMG_6791_zpscsjxro7x.JPG?dl=0

Some of the stringy plastic is from printing collapsed supports, but it's the blobs on the outer wall that I can't live with.

Any advice to solve this would be greatly appreciated. Thanks in advance.

Edited by Guest

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First and foremost make sure the infill printing speed is the same as inner and outer shell speed. If the infill is faster then it builds up too much pressure and when it slows down for the outer shell you get issues like this. however this looks more like typical retraction stringing.

The easiest way to fix this is to just print even slower. Try 30mm/sec and again make sure *all* printing speeds are the same (travel speed should be fast - 150mm/sec is reasonable).

Other possible fixes if you want to push the speed a little faster would be to do thicker layer heights (just to save time) and cooler printing temperature (cooler filament means less leakage).

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Thanks for the suggestions gr5. I didn't have all of the settings exposed for speed so I was only setting the print speed and travel speed (45mm/s and 250mm/s respectively). After exposing the other speed values this is what Cura had them set to:

Print Speed: 45

Infill Speed: 45

Wall Speed: 25

Outer Wall Speed: 17

Inner Wall Speed: 25

Top/Bottom Speed: 25

Support Speed: 17

Support Infill Speed: 17

Are you suggesting that I set all of these speeds to something like 30mm/s? As I'm already having issues with supports detaching wouldn't increasing this speed be problematic?

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I'm getting the same result no matter whether I print with 0.04mm, 0.1mm or 0.15mm layer height. I'm generally printing at 230 degrees people to head and 80 degree build plate. My print speed varies from 45-60mm/s depending on layer height.

Do you vary layerheight by selecting a quality profile, or do you manually change the field "layer height"? Same question about speeds?

Most quality profiles supplied with Cura perform pretty well. From those profiles, you can start optimising for your part. But starting with a profile, and then altering the layer height manually sort of renders the profile useless.

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Do you vary layerheight by selecting a quality profile, or do you manually change the field "layer height"? Same question about speeds?

Most quality profiles supplied with Cura perform pretty well. From those profiles, you can start optimising for your part. But starting with a profile, and then altering the layer height manually sort of renders the profile useless.

 

I've been selecting the quality profile first and then making adjustments. I didn't find a noticeable benefit by using 0.04mm so I've been using 0.1mm for this specific print.

The values I got above come from the 0.1mm profile and I've then just changed the print speed value to 45mm/s. This automatically set the values I have above.

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Are you suggesting that I set all of these speeds to something like 30mm/s? As I'm already having issues with supports detaching wouldn't increasing this speed be problematic?

 

Yes. At least for a test. Everytime you switch to a slower speed it will overextrude for a few seconds and every time you switch to a faster speed it will underextrude for a few seconds. I have never needed to go below 20mm/sec. 30mm/sec should be plenty slow enough for high quality.

I'm wondering if you should raise the temp to 230C. I have never printed ABS on my UM3 (only um2 and um2go) and when I do I prefer around 240C.

Also for ABS it's important to do as little fan as possible. If you do too much fan the layers won't bond and the part will break easily along the layers ("grain"). Definitely don't go over 3% fan. 1% might be enough (this is for UM3 - for UM2 you want 30 to 50% fan). If you have zero fan then it won't do overhangs or bridges very well. If the layers don't bond they sometimes even peel apart in the middle of a print while it's cooling.

Also with ABS I recommend you put a front and top cover. It can be as simple as a bag or saran wrap for the front and a copy paper box for the top (copy paper boxes are perfect fit for the top of the machine with plenty of space for the bowdens in the back). Doing these covers raises the air temp to about 35C which helps quite a bit with materials that have a higher softening temp such as ABS.

PLA is much easier to print.

Could you supply a photo - maybe that will help us understand your issue. I may be misunderstanding what you mean by "blobby" part.

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I'm at 230 degrees at the moment. I might try 240 and will also experiment with covers.

These are the blobby bits I'm talking about circled in blue:

https://www.dropbox.com/s/t6o8wsvzau8qu1n/Capture.PNG?dl=0

The stringy bits are mostly bits of support that the printer is trying to print when the lower section has already fallen away.

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Thanks for the picture.  That's what I thought you were talking about but it's good to be sure.  yeah that's typically overextrusion issues.  Due to speed changes and many other possible causes.  Basically lower speed in order to lower pressure.  Lower temperature so that the viscosity keeps the plastic in it's place instead of bursting out as a little blob.

So, um, I think lowering the temp is better.  I'd try 30mm/sec at 195C although the default temp is probably fine also (200C i think?).

Edited by Guest

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I've just done another test and the print is much improved just with the lower speeds. Infill is looking good, however, I am still getting collapsing supports.

I tried adding a base to the supports to help them stick better but they keep falling off mid-print. They just seem to topple over. The biggest problem with this is that the printer obviously keeps trying to print the support and ends up dragging stringy bits of filament all over the print.

Aside from turning supports on and adding a base to them, I've left all the settings on the default. Anything else I can try?

Edited by Guest

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Watch this - there are a few techniques to get things to stick VERY well to the glass. It's a long video, sorry, but I didn't want to leave anything out. I tried to mercilessly edit it down to keep it as short as possible. Removed 1 second pauses here and there and speed up some of the video:

 

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The best way to show you the supports is in Cura:

https://www.dropbox.com/s/dhynilgxvthzch3/supports.JPG?dl=0

They're fairly high towers and they just detach from the model mid-print. The funny thing is that when I first started using the UM3+ the supports where one of the most impressive things about it because they seemed to print and detach perfectly, better than any other printer I've used.

The only difference I can think of was that I was only printing one model at a time then and I was using the 0.06mm profile. I've now gone back to the 0.06mm profile as the Support Bottom Distance can be as low as 0.06mm. Perhaps the supports will attach better with a smaller layer height? I'll find out soon enough as I've just set another print off so fingers crossed.

Edited by Guest

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You said you are printing in ABS. Are those supports in ABS also? I just prefer to create my own supports in CAD for this kind of thing. Just build the supports right into the STL file for CURA and turn off cura supports. That way the supports can be firmly attached to the print bed and get smaller as they get up to their function location.

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