Loose filament when I Print screws or screw type print

Every time I print anything that screws into anything, I get strings of filament between the spiral parts of the design. Such as the Sunlu spool adapter and the screws from Buildfinity both have strings that make the screws break or the parts get stuck when I try to screw them into the corresponding parts.

The top is where I screwed the pieces together and got it stuck and had to work it back apart. This is using Bambu Basic Pla in red but I tried it in clear (Sunlu filament) and with Elegoo’s (grey PLA) got the same results.

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Try printing the screw from my model.

I printed it on the A1 mini and in a matte PLA material and had no stringing.

Using matte in particular is a stress test for things like screw threads, so I know that works great.

You can use it to compare, if it works, see the print profile differences.

You don’t have to tint the whole lot, just select the screw from the accessories profile. You can do that in both Bambu Handy and Babu Studio.

If your walls are outer-inner, change them to inner-outer for threaded parts.

Otherwise, it might not be cooling enough, so you might need higher fan speed. Or it could be:

  • not enough retraction
  • too high temperature
  • printing too fast
  • printer not calibrated
  • wet filament
  • partial nozzle clog
  • poorly designed 3D print

Standard threads do have a relatively high overhang with 60 degrees thus are a little more demanding and do need a well tuned print/filament profile.
Generally PLA works ok and a reduction in layer height can help with adhesion at the tip areas of the threads.

If you have access to the step file of the model you can fillet the crest of the thread.

Printing at a lower layer height will also help.

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check the box to enable dynamic overhang speeds

I think since the screw on your design is so small it printed without issue but I couldn’t figure out what settings I needed to change since I still need to figure out what each of the settings produce. I will say your design is so awesome that I’m going to print one for myself. Thank you

That box is checked and it has overhang speeds based on the percentage of overhang:
10% - 25% No speed decrease
25% - 50% 50mm/s
50% - 75% 30mm/s
75% - 100% 10mm/s

As I stated in another post here I’m new so I must do a little research on what these number will do to whatever I’m trying to print. I’m learning so much from these forums. Thank you

thats plenty slow enough, the other 2 main factors are fan and temp.

fan should be maxed, temps if good elsewhere are not gonna really be a golden bullet, but drop em to 200 or less and try one. use a .2 layer until you have the culprit(s)

What is the diameter and height of your screw? I may do some testing if I have time.

Keep in mind, if a small screw prints, a big one will. It is the angles not the scale that cause issues.

Mine prints without any supports.

Hey thanks for your response! The screw in the picture is 60mm diameter and 60mm tall. It was for one of the Sunlu adapters. But you are correct the small screws from Buildfinity had the same issues (I threw away the broken ones and the rest my grandson has already taken them home).

What is the link to the model?

Have you tried printing at .16 or lower layer height? Also make sure the wall order is inner first just in case someones changed from standard.