Prints are coming out blobby, not the fault of Cura settings

[Anonymous]

I've been making a few things in Fusion 360 and sending them straight to Cura. When they print, the bottom layers print fine, but the top layers have all kinds of little blobs and zits, sometimes to the point of total unusability. This has happened with two different designs. Things modeled in a different program come out 100% perfect. Adjusting settings may slightly lessen the problem but no matter how optimal the settings, the result is still the same: blobs.

I'm still kind of new to 3D printing so I could easily be doing something wrong, but I know it's not the printer itself.

Additional info, if it's necessary:
- Printing on a Monoprice Select Mini v2
- Sending the models straight to Cura (basically my only option), tried many, many different settings
- Also tried exporting the STL to Blender for adjustments and printing and still have the same issue.

Here's pics:

In the last pic, my printer messed up and printed the eyes off center. This has been fixed, but the blobs are still happening. This is just the only example I had on hand to show what I mean. The printer has been completely calibrated and is printing correctly again. And the design on the spheres is supposed to be a star like in the first pic.

[algor_neil]

Post your STL file here

[lichtzeichenanlage]

I'm using Fusion 360 all the time to design my stuff to be 3D printed and never hat such a problem. If your conversions are fine, it might also be a problem with your printer.

Could you please not only post the STL file but also the exported Fusion file and the gcode here. You might have to Zip it and/or rename the file extensions to .f3d to bypass the forum filter.

[etfrench]

It's either your printer or Cura settings or the filament.  You may be over extruding or there may be too much moisture in the filament.

[daniel_lyall]

That does look like prints I get when the filament is wet, all files need to find out whats going on with that

[lichtzeichenanlage]

@etfrench: Over extruding would or to high temperatures would be my guess, too. 

[Anonymous]

Other prints are coming out 100% okay though. No blobs at all with the same printer and same settings. Would that still possibly be the case then?

[lichtzeichenanlage]

Without having f360 export, STL and gcode it's not possible to point to the
source of the error.

[Anonymous]

I don't know how to get the gcode yet but here's the export and STL.

[lichtzeichenanlage · Accepted solution]

The design contains some bad errors. Are those errors in your project, too?

[lichtzeichenanlage]

Perhaps this link and those videos might be interesting for you, too.

[Anonymous]

Thanks, this is what I was worried about. I don't know how to see the errors but I'll play around and see what I can figure out.

I really appreciate your help, thank you.

[lichtzeichenanlage · Accepted solution]

I know that I'm kind of late... But I spend some minutes to create an error free implementation of your design. 

As you can see you just need to sketches, a construction plane and four features to solve the riddle. You can even use the parameters (the sigma / sum sign) to adjust the dimensions.

[Anonymous]

Thank you so much for going to all of that effort! So I'm going to assume that it's my method that's flawed, because I recreated the entire thing in a new environment and hit CTRL+B and no errors came up, but I'm still getting a terrible print.

My method would be:

Create a half sphere using a sketch and revolve.
Making a sketch in the shape of a star.
Extruding the star sketch down into the sphere.
Adding fillet and chamfer by selecting the edges of the star.

What you've done is completely beyond my skillset at the moment, so I'm going to have to do a lot of research, I guess.

I was going to ask to see your file, but you already attached it. Thank you SO much! You're really a huge help.

[Anonymous]

I ran a test print of the eye from your file with my typical settings that are working for everything else, and I got the same issue. It was slightly less than normal, but still very blobby on the top few layers. I'm not sure what to do at this point. 😕

Did you print it, too? And if you did, did it come out correctly? 

[lichtzeichenanlage]

Right know I don't have access to my printer because I'm on a business
trip. Sry

[daniel_lyall]

@Anonymous what are your export settings this is mine 

I just printed @lichtzeichenanlage version and it is fine. 

 

[lichtzeichenanlage]

@daniel_lyall: Thx for stepping in and that you did a test print. I'm more and more convinced that the solution should be found in the print settings. Checking that the STL has a detailed mesh is a good starting point.

@Anonymous: Can you check if the bloobs do appear if the printer starts to print e.g. a layer or after it moved to a different place and starts printing again?  

[Anonymous]

@daniel_lyall Thank you for helping out!

@lichtzeichenanlage This is just weird. I've tried every solution I can find online with the settings. I'll have to watch it closely as it prints but I'm thinking it might be after it moves to a new place, since the top area around the points of the star are the most heavily blobbed.

Here's a pic of the eyes I printed overnight, showing the difference in the amount of blobs without changing any settings. And a calibration cat that I printed before test printing the eye you made.

[lichtzeichenanlage]

Okay - after moving. If a the print head moves without printing for a certain distance, it pulls in the filament / plasitc for a millimeter or so. This is done to avoid that molten plastic drops out of the nozzle. This pulling back mechanism (in combination with other features) is called retraction. The theory is, that this isn't necessary for short distances because it will start printing very soon and there will not be to much plastic. Your modle is tiny and because of the cutout the printer stops / starts printing often. If you're printing pretty hot or the part cooling fan does not cool enough might work against this theory. 

What are your retraction parameters and at what temperature are you printing what kind of plastic (PLA/ABS/etc.). What is your nozzel size and layer hight?