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What happened to my walls?

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Hi All,

I have yet another great puzzle for you. I printed this particular piece of a housing, by our own design. It has been made by a "professional" 3D printer, so I'm pretty sure my post-processing is good, the file is fine.

Then, as part of my ongoing experiment to use the ultimaker to speed up our product development process, I tried to print it myself. And this is what I got. I used the standard Cura settings (I did open the "expert settings tab"). It is PLA, the should not have been a problem. The only thing I did find, is that when I start a print, I have to manually set the nozzle temp to something, by default is says 0 degrees.

Where did my walls go? I made the print upside down, because I need a smooth outer surface. This did mean a lot of support was required. But there seems to be a mesh where my walls should be?

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5a331a1440398_IMG_72311.thumb.JPG.386c31e61bd30e1ae9d5f117396d0d34.JPG

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Did you by accident put 0 shell? i have before and my stuff came out like that.

 

No, my shell thickness was set to 0.92 (2* my nozzle size) and the shell speed was set to 9.7mm3/s

I checked it twice, I really don't understand

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First of all NEVER PRINT BEFORE CHECKING LAYER VIEW. You would have seen these problems ahead of time.

You have 3 problems.

1) The "mesh" you refer to is support material. In slice view you would have seen this as a grayish teal color. You should probably turn off all support.

2) Your walls probably were too thin - they need to be at least .8mm thick to print with a .4mm nozzle and even then they might not print due to floating point errors so I recommend 1mm thick walls. However rather than do massive edits to your CAD model you can "lie" to cura and tell it you have a slightly smaller nozzle but you must change shell width to be multiple of nozzle size or nothing will change. So experiment with .3mm .2mm .1mm or whatever it takes to get the walls to appear. The farther you stray from the actual nozzle width the worse the qualtiy gets but .35mm is excellent quality output for a .4 nozzle and .3mm should be acceptable also. .2mm - will if that's what it takes then don't print it. So play with this and look at it in slice view and see what gets your walls to re-appear. Again - CHANGING NOZZLE SIZE DOES NOTHING IF YOU DON'T ALSO CHANGE SHELL. So .35mm nozzle and .4mm shell gives you .4mm lines. .35mm nozzle and .7mm shell gives you .35mm lines. It's actually easy to leave the nozzle size at say 1mm and just adjust shell at first to get your walls to appear and only then make the values make more sense e.g. nozzle .31mm shell .62mm.

3) You have quite a bit of underextrusion - there are lots of gaps on the top layer. This is probably the hardest problem to fix as there are dozens of possible causes but the simplest is temperature and speed. Try printing it either 20C hotter or at half the speed you had used. What was your:

layer height, speed, temperature?

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By the way - that's a ridiculous amount of support. You may have trouble printing this with no support but ideally you only need it in the rounded corner area. Not printing support can save you tons of time but the print might not come out proper. Personally I would build my own support in cad at those rounded corners where wall meets roof and then leave the central flat ceiling unsupported as that will print pretty well. Removing support and cutting the print speed in half should make it print in the same amount of time with less underextrusion.

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First of all NEVER PRINT BEFORE CHECKING LAYER VIEW.  You would have seen these problems ahead of time.

You have 3 problems.

1) The "mesh" you refer to is support material.  In slice view you would have seen this as a grayish teal color.  You should probably turn off all support.

Hi GR5, thanks for responding to my post so elaborately, so let me get back to you point by point. I am new to this forum, but not to 3D printing. The support in Cura is grey, the walls are red and the fill is yellow. Check, check and check. The top of my print looks red in the Cura view, so do the outer walls. I do really need the support, I am trying to span a length of 105mm and a width of +/-55mm wits a 120mm radius curve. That's as good as horizontal.

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2) Your walls probably were too thin - they need to be at least .8mm thick to print with a .4mm nozzle and even then they might not print due to floating point errors so I recommend 1mm thick walls.  However rather than do massive edits to your CAD model you can "lie" to cura and tell it you have a slightly smaller nozzle but you must change shell width to be multiple of nozzle size or nothing will change.  So experiment with .3mm .2mm .1mm or whatever it takes to get the walls to appear.  The farther you stray from the actual nozzle width the worse the qualtiy gets but .35mm is excellent quality output for a .4 nozzle and .3mm should be acceptable also.  .2mm - will if that's what it takes then don't print it.  So play with this and look at it in slice view and see what gets your walls to re-appear.  Again - CHANGING NOZZLE SIZE DOES NOTHING IF YOU DON'T ALSO CHANGE SHELL.  So .35mm nozzle and .4mm shell gives you .4mm lines.  .35mm nozzle and .7mm shell gives you .35mm lines.  It's actually easy to leave the nozzle size at say 1mm and just adjust shell at first to get your walls to appear and only then make the values make more sense e.g. nozzle .31mm shell .62mm.

/quote]

My walls are 2mm thick. As i said, shell was set to 0.92mm, nozzle to 0.46.

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3) You have quite a bit of underextrusion - there are lots of gaps on the top layer.  This is probably the hardest problem to fix as there are dozens of possible causes but the simplest is temperature and speed.  Try printing it either 20C hotter or at half the speed you had used.  What was your:

layer height, speed, temperature?

 

That's the whole point: that's not underextrusion, I'm pretty sure thats the mesh fill. In normal printing it makes the outer shell solid and the infill (26% in this case) by crossing lines. I do not have the 0.96 shell thickness anywhere, but I only have the 26% fill where my walls should have been.

The crazy thing is: I printed it again, and it was fine. Nothing changed but the speeds were brought down by 5mm/sec (all of them). I just toggled Cura to quickprint, selected "fast print" toggled back to expert mode and brought the speeds down. It looks great. I will post a pic tomorrow for reference. I repeated the same steps for the opposite wall, thinking that I did accidentally change a setting before. But now I have the same problem again: all support and fill, no walls.

ARGH!

my temp is set to 215, layer height to 0.15 and speed to 50mm/sec, for PLA

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If you are new to this dont fiddle with too many settings. Its asking for trouble. You wont know were to begin if something goes wrong. Its very easy to forget you ticked something or changed values. Ive done it many times. If it printed ok once and not the second time, then YOU have changed something, you need to backtrack and figure out what it is. I print EVERYTHING with 1.2 shell and NEVER had any issues with walls since switching from 0.8 which i had many problems with. Leave the nozzle at 0.4 if thats what you have, and as gr5 said thats a silly amount of support, this is where bridging becomes your friend.

And as someone new to 3d printing you really should not be starting on objects with extreme overhangs. You are going to learn things the hard way, or should i say the frustrating and infuriating way.

Dont try and run if you cant walk.

Edited by Guest
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Dear co-ultimakers,

I know you mean well, but this is not really the help I need. As i said before, I m not new to 3D printing. I have been in design engineering for over 10 years now. I have been using 3D print hubs for about the same time. I have worked with a resin printer (Form 1) was a while in my previous job and a Flashforge machine as well. I have never worked with Cura and Ultimaker and yes, that's frustrating the hell out of me. So please, read my posts? As I said, I did NOT change many settings, just increased the speed of the "standard" settings by 5mm/sec so it would fit into one working day. The print shown below is the same print, printed with half the supports and it is fine. SAME PRINT, STANDARD SETTINGS. I DID NOT CHANGE THE SETTINGS FOR THE THIRD PRINT, AND I GOT THE PARTS AS IN THE LAST PICTURE. What is happening? Could it be the Cura update? I did not update to 15.04.5 yet, though Cura itself says it's the latest version. Which is odd, but ok. If only that was the worst of my problems...

IMG_7247.thumb.JPG.674929364905301294cd8bf5433c7dbf.JPG

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IMG_7249.thumb.JPG.f0505f29548b2b0a4cb606c7941ef3d2.JPG

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First of all

Standard settings are to print fast stuff. You need to learn the advanced mode if you plan to print seriously on any machine.

Shell thickness as a general rule must be proportional to the nozzle. 2 layers are for 0.4 nozzle a 0.8 shell, 3 are 1.2 and so on

Since you said it printed well once I would import the profile from that gcode and process it again.

Also you need to show us the screens of the settings of that print, no matter what you selected. Maybe there's a bug that has set your top layers to 0. Anyhow, without all the info (not just 'standard settings') it's hard to help you in anyway (even if you only adjusted 1 parameter). .

Edited by Guest

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First of all

Standard settings are to print fast stuff. You need to learn the advanced mode if you plan to print seriously on any machine.

Shell thickness as a general rule must be proportional to the nozzle. 2 layers are for 0.4 nozzle a 0.8 shell, 3 are 1.2 and so on

Since you said it printed well once I would import the profile from that gcode and process it again.

Also you need to show us the screens of the settings of that print, no matter what you selected. Maybe there's a bug that has set your top layers to 0. Anyhow, without all the info (not just 'standard settings') it's hard to help you in anyway (even if you only adjusted 1 parameter). .

Hi Neotko,

These are the settings I used. This print (yet another part) is coming out fine. It's printing as we speak. I did not change the settings after yesterdays failed print. I did not even shut down Cura, I just closed my laptop and tried again today, hoping a different model would come out better. It all seems pretty random to me, I really hope you can help.

set1.thumb.jpg.1effdf88ce5107ae9e93577b1de3cb3a.jpg

set2.thumb.jpg.61a22210968aed92edca139feccb6ebe.jpg

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Ok. The first I see it's way too many speed changes. General speed it's at 50mm/s but infill it's at 100 and inner shell 80. As a general rule (the default profile if was like that it quite sucks) you need to try to print everything at the same speed, and you can go 5-10% up or down. But never (not recommend) a 200% more for one kind of infills/etc.

If you set all the advances/speed settings (except travel that you can raise easily to 180mm/s) set them to 0. This way you will control the speed from the Basic/Speed that you have at 50mm/s

Or just change that infill and inner shell to 40-60

The changes in speed that high while printing make an unatable flow from the extruder because it has to change speed. That can cause underextrusion, and errors while printing.

Try that and let's see how this goes.

Also try to read this guide, not to fix problems but to learn more details about how the slicer thinks and works. It helps in the long run to print better and better.

http://support.3dverkstan.se/article/30-getting-better-prints

Edited by Guest

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Ok. The first I see it's way too many speed changes. General speed it's at 50mm/s but infill it's at 100 and inner shell 80. As a general rule (the default profile if was like that it quite sucks) you need to try to print everything at the same speed, and you can go 5-10% up or down. But never (not recommend) a 200% more for one kind of infills/etc.

If you set all the advances/speed settings (except travel that you can raise easily to 180mm/s) set them to 0. This way you will control the speed from the Basic/Speed that you have at 50mm/s

Or just change that infill and inner shell to 40-60

The changes in speed that high while printing make an unatable flow from the extruder because it has to change speed. That can cause underextrusion, and errors while printing.

Try that and let's see how this goes.

Also try to read this guide, not to fix problems but to learn more details about how the slicer thinks and works. It helps in the long run to print better and better.

http://support.3dverkstan.se/article/30-getting-better-prints

Hi Neotco,

Thanks for your help. I will go ever the guide, see if there's something I can do to improve the prints. I did find the "picture guide" from the same website, which was also quite helpful. I guess I just did not look any further.

I will try to print again after Easter, but I will let you know how it goes.

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Try to save all you gcode files of every print you ever made with notes so you know which gcode goes with which photo. That way from cura you can do "file - load profile from gcode..." and check exactly what your settings were for a print.

Some of the things you say don't agree with each other - something isn't quite right:

The pattern on the very first photo above could either be 50% infill showing at the top (not top layers to cover the infill) or it could be heavily underextruded solid layers. I assumed the later because people don't usually choose 50% infill and in fact you seem to think the infill was set to much less in your later posts. So I still stand by the fact that the first print was extremely underextruded - by about 50% (50% of the material is advancing through the nozzle as desired). Lowering speed by 5mm/sec shouldn't make any difference instead while it's printing go to the tune menu and cut the speed in half and wait for 10 lines to be drawn and listen to the speed change and then re-evaluate and adjust the speed from there.

Changing speeds on walls versus infill can indeed cause exactly what we saw. 100mm/sec with .15mm layers and even at 240C this is challenging but I assume you were much cooler than 240C (sorry if you said I read some of your posting yesterday). The cooler you print the more viscous the filament is (think toothpaste at 190C and honey at 240C) so you have to print slower at cooler temperatures but it's worth it if you want extra nice quality.

There is a very very recent bug in cura that changes nozzle size to .46 even if your actual nozzle is .4. Ultimaker is just now recommending going 7/8 if anything so after years of recommending .4mm nozzle size setting for .4mm nozzle they are now thinking putting .35mm in Cura (lying) which is the opposite direction of your .46. Anyway having it at .46 means it has to push that much more plastic through that tiny nozzle which also increases underextrusion potential so I'd change that (and change shell to .8 as shell should always be an integral multiple of nozzle size (unless you are an expert and understand the actual code of how it chooses line width).

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Regarding bridging:

If the roof of that first photo is bridged on a single layer the UM2 can do it no problem with PLA. The UM2 can bridge completely from one side of the print bed to the other if it happens suddenly on the next layer up. If it is a gradual bridge forget it. Almost impossible.

So you may be right that you need the support everywhere but if it's indeed level you don't need support for that section.

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...snip

There is a very very recent bug in cura that changes nozzle size to .46 even if your actual nozzle is .4.  Ultimaker is just now recommending going 7/8 if anything so after years of recommending .4mm nozzle size setting for .4mm nozzle they are now thinking putting .35mm in Cura (lying) which is the opposite direction of your .46.  Anyway having it at .46 means it has to push that much more plastic through that tiny nozzle which also increases underextrusion potential so I'd change that (and change shell to .8 as shell should always be an integral multiple of nozzle size (unless you are an expert and understand the actual code of how it chooses line width).

 

As an aside, there is another thread on this subject and I have been testing these past few days. Yesterday I saw that .35 gave a significant increase in dimensional accuracy over 0.4, although so far the finish quality has been almost the same - I do need to fully evaluate this dimensional result. In all cases .46 has provided the worst results, not bad, indeed quite good but not as good as the thinner settings.

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