Bottom surface of printed model seems to be missing  

RE: Bottom surface of printed model seems to be missing

First of all, was the file you downloaded a pre-sliced .gcode file or .STL file?

RE: Bottom surface of printed model seems to be missing

STL. Somehow the forum does not allow me to post the stl file. It is located as follows:

https://drive.google.com/file/d/1cgXCGpBY86U65iHCkmH8OkG5s1qTAdFA/view

RE: Bottom surface of printed model seems to be missing

Ok, let me try slicing it and see what I get.

RE: Bottom surface of printed model seems to be missing

Ok, I sliced it with Prusaslicer (more or less latest version) and it definitely shows solid infill on the bottom so many layers.  I'm attaching a screen shot of the bottom of the slice.

What are you using to slice it?

RE: Bottom surface of printed model seems to be missing

Thanks. I am using PrusaSlicer 2.2.0 based on Slic3r. I am using Prusament PLA.

Are there settings that I may need to change? Last time when I printed using PETG, support asked me to change some parameters values. It seems that whenever I launch the slicer, those values remain.

On the top left, I have 0.15mm QUALITY, Prusament PLA and Original Prusa i3 MK3S, None, Infill 15%.

RE: Bottom surface of printed model seems to be missing

That's what I am using, and I just used the defaults for a generic PLA, which was what I was using for a piece of a project I am working on.

You mentioned a raft.  Is there a particular reason you used a raft?  That may have something to do with it.

If you need me to, I can re-slice it using .15 quality and post the .gcode.  The only gcode tweaks I've made from default are to turn off two nag messages.

RE: Bottom surface of printed model seems to be missing

I just looked at the bottom of the model in the slicer with no raft. Unlike yours, there is no purple part but orange part like the one shown in the photo.

RE: Bottom surface of printed model seems to be missing

Posted by: @jsw

That's what I am using, and I just used the defaults for a generic PLA, which was what I was using for a piece of a project I am working on.

You mentioned a raft.  Is there a particular reason you used a raft?  That may have something to do with it.

If you need me to, I can re-slice it using .15 quality and post the .gcode.  The only gcode tweaks I've made from default are to turn off two nag messages.

Yes please. It is good to find out what is wrong with my slicer. Don't know why the purple part is missing on mine.

I used raft because few days ago I made a print that had warping. I read that raft could solve that issue so I added raft this time.

RE: Bottom surface of printed model seems to be missing

Here you go.

.15mm Prusament PLA.

RE: Bottom surface of printed model seems to be missing

Peter the only reasonable way to debug these issues is if you save your project from slicer (save project as) which will save a .3mf file.  The 3mf file will contain your model and all your slicing and printer settings.  With those people can look for any obvious issues and slice, preview, modify and slice again etc.

You need to zip into an archive any files as the forum doesnt accept most file types as you have already discovered.

I notice from your screen grab that you have a colour change at 9.8mm and the preview is in colour mode rather than feature mode which is why yours doesnt have the same colours that JSW's does.  Also looks like the linked gcode was sliced for a MMS printer given the name ? Do you have a MMS setup or is it a normal MK3 or MK3s ?   Thats another reason that project files are handy as you can slice using the same settings as a starting point but say adjust the filament type used for your materials on hand if different.

It could be that during your previous changes you turned bottom layers to 0, that would result in no bottoms.  Without the project there are far too many variables to know, its pure guesswork.

RE: Bottom surface of printed model seems to be missing

Thanks jsw.

neophyl: I don't have the 3mf file. Do people usually save the 3mf file?

I do not have MMS setup. Just a regular i3 MK3s.

I printed another model. So far, it seems to be that if I don't have raft, one edge get curled especially at the region where it is close to the left edge of the build plate. Could this be due to uneven heat across the build plate? If I enable raft, say 2-3 layers, the warping issue is fixed but then again, the bottom surface is not printed. Here is photo. 

I noticed that when I enabled raft, other dimmed parameters got turned on. Is there a setting that when the raft is enable, the bottom surface is not printed?

RE: Bottom surface of printed model seems to be missing

Here is the 3mf file with raft set to 3. 

RE: Bottom surface of printed model seems to be missing

Enabling raft is enabling support so those settings get turned on if they weren't on before.  Using a raft should NOT result in no bottom layers though.  Again without a project file that actually has the issue anything is guessing.

Personally I always save as a 3mf  file (Save project), basically before I hit slice.  Its a habit I have gotten into.  Largely out of running the alpha and beta versions when available.  There is always a chance that Slicer could crash when slicing, some dodgy models can cause that and the chances are higher with the pre release versions.  When you save a project you can load it back in after a crash and any work you did placing models or modifier meshes is all saved along with all the settings.  So its very easy to return to something and tweak it again, change filament, adjust things to make printing easier etc.  In the long run it can save a lot of work.

If PLA is curling up then the first thing to look at is bed adhesion.  Its a common answer but its the single most critical thing which is why it gets so much use.  Long thin things are problematic but the next step is adding a brim to increase surface area.  Rafts were more common when bed levelling wasn't so good and adhesion was spotty and are really only useful for objects with irregular bottoms these days.  

That stand stl file should print perfectly fine with no brim, no raft, basically just as it is with the .15 quality profile.  I've just set the printer going.  Its not Prusa PLA but some no name brand that I have used before for test prints last year.  I'll let you know how it goes when its finished.

RE: Bottom surface of printed model seems to be missing

OK It looks like I was replying and setting the print off while you were posting the project file.

Looked at the project file and at your pic again to compare the sliced preview.  You do have your bottom surface, its visible in the picture you posted.  However its a bridge bottom surface which is the result you get when printing on a raft (support).  That means the lines are not squished together like they would be on a normal bottom.  Thats what printing on a support layer gets you as theres a gap between.  If there wasnt you would have the raft fused to the part.  

I'll re-iterate that the part that is in the project file and the stand stl you linked to earlier should both print perfectly fine without any raft or even a brim being needed.  If it doesnt then you really have to look at either bed adhesion or your fist layer z height. 

After the stand has finished printing I'm going to take your project and turn off the raft only and then try printing that.  Normally for a functional part I would increase the perimeter count to 3 but I'll leave it as is as we are trying to see if there are any other issues to printing this part except for bed adhesion.

RE: Bottom surface of printed model seems to be missing

@neophyl

Thank you. I may be wrong but so far, it "seems" to be that whenever I print long things without raft, curling occurs even with PETG. Here is another example: 

https://forum.prusa3d.com/forum/english-forum-general-discussion-announcements-and-releases/what-could-be-the-reasons-for-this-printed-failure/

RE: Bottom surface of printed model seems to be missing

both prints with no name pla printed fine.  I'm actually embarrassed to post pictures as my bed needs a severe cleaning :), but even in the state it was in, there was zero warp or lifting.  Using your project for the second one with a single change for setting the raft to 0 to turn it off.

RE: Bottom surface of printed model seems to be missing

Thanks for testing. So what have we found out?  For my printer, it seems to be that for long objects, if I don't use raft curling occurs. If I use raft, the bottom surface do not get printed. What can I do to solve the problem? I tried brim instead of raft for two times. Both tests failed and resulted in spaghetti within the first 10-20 seconds. 

RE: Bottom surface of printed model seems to be missing

As pointed out your picture showing 'no bottom layers' DOES have bottom layers.  Its just the type of layers you get because you are printing on support.  Raft is support.  Layers printed on support do not fuse together properly and generally are bad looking.  They basically match your picture.  I reprinted the lower section of your project with the raft enabled, and as expected there were bottom layers and they pretty much looked like your pic, ie terrible.

What we have learned is that for some reason pla parts that are not difficult to print normally warp on your printer.  The most common causes for this are-
Incorrect first layer Z height - remedy, use the Jeff Jordan method and tune it until it is correct.  Post a picture of the 75mm square from that process and get feedback.
Bed not clean - remedy is to properly clean your bed using dish soap and hot water rinse.  Just follow the instructions in one of the MANY posts on this issue where Joan has posted her excellent advice.
Bad batch of PLA - try a different type / brand of PLA, however as you have also previously stated that you have the same issues with PETG then that would strongly suggest its issue 1 or 2 or possibly both.  PETG with a smooth sheet that is clean sticks too much.  I've seen it lift the bed itself away from the magnets it sticks that well.