Printer Help - how to handle a small step inside a cylinder?
First, I have read @zoltan's post on how to ask for help but I am fairly new to 3D printing and this is my first post. If I am asking something that has been answered elsewhere, please help me find it as I have tried to search the forum. Part of my problem may be that I don't know the vocabulary of 3D printing well enough but I am looking forward to learning.
My setup: Original Prusa Mini (4.2.1) - 8 months old with all the standard nozzle, Prusament PLA filament, Prusa Slicer 2.3.
My STL file is attached which I created in OpenSCAD. I am using the 0.15mm Quality setting and have tried the suggestions in this post to reduce stringing. detect bridging perimeters (on) 
I am trying to print a very simple spacer with annular indents at both ends. As you can see from the picture, I get a clean top with the small indent but the bottom indent has significant stringing and hanging threads. I was hoping that the options mentioned above in v2.3 of the Prusa Slicer would help but no joy.
Here are the associated files: Archive
Any advice on how to print this seemingly simple object? Thank you
Chip McClelland
See Insights LLC
RE: Printer Help - how to handle a small step inside a cylinder?
Hi Chip,
Welcome to the forum,
Have you tried supports?
PIR Spacer
as you have found the search engine is a bit rubbish...
hopefully someone will answer your post soon.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Printer Help - how to handle a small step inside a cylinder?
Thank you for the reply. Yes, but taking out the support on the inside of that annular step is almost as bad as cutting out all there loose threads. Would be open to any other ideas.
Chip
Chip McClelland
See Insights LLC
RE: Printer Help - how to handle a small step inside a cylinder?
You've got 2 different issues:
- Printing the step overhang without support beneath it.
- Poor adhesion inside the cylinder.
The first is, as Joan notes, a problem most often solved with supports. The Prusa printers can handle a surprising amount of overhang well, but at some point, they will fail without supports. Anything -- literally -- printing in air with nothing beneath it and no connection to the far side is going to require some help. That's where supports come in. Supports can be annoying to remove, but I get good results with these settings:
- Contact Z distance: 0.25mm
- Pattern spacing: 3mm
- Interface layers: 4
- Interface pattern spacing: 0.2
- Interface loops: off
Even on a small 20mm shape, these supports pop out easily. You can try reorienting your part to reduce the amount of support required.
The adhesion problem is caused when the newly extruded filament doesn't have sufficient adhesion to the layer below. It gets pulled taut across the opening. Though this is often mistakenly identified as stringing, it's really an adhesion issue. You can address it by:
- Slowing down. Slower speeds allow the filament to bond better with the layer below.
- Increasing heat/reduce cooling. Hotter filament will adhere better. Increasing temps may contribute to stringing, so reduce cooling if possible.
- Applying lower layer heights. Higher layer heights produce extrusions that can be more circular in cross-section, with none of the oval/stadium cross-section "squish" that provides good adhesion to adjacent layers. Note that you can apply lower layer heights only when necessary using Variable Layer Heights.
RE: Printer Help - how to handle a small step inside a cylinder?
@chipmc
Hi Chip,
did you try my setup?
I have changed the Z separation to make removal easier!
standard is 0.1mm I have used 0.2mm
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Printer Help - how to handle a small step inside a cylinder?
@joantabb and @bobstro,
Thank you for the advice. I tried the print again with supports and got a much better result. Not as smooth as the top but perfectly serviceable for the task. 
Thank you both!
Chip
Chip McClelland
See Insights LLC
RE: Printer Help - how to handle a small step inside a cylinder?
Hi Chip,
did the support come out easily?
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Printer Help - how to handle a small step inside a cylinder?
yes, quite. Thank you
Chip McClelland
See Insights LLC
RE: Printer Help - how to handle a small step inside a cylinder?
@chipmc
it's worth ticking the option for removable support.
makes life easier...
Regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Printer Help - how to handle a small step inside a cylinder?
@joantabb
Yes, tried that and had no problem getting the support material off. I have now saved all these settings in a project and will use for future prints.
Chip McClelland
See Insights LLC
RE: Printer Help - how to handle a small step inside a cylinder?
@chipmc
Excellent!
Note, there is another setting which trips people up occasionally, it's the 'Don't support Bridges' option... which is ticked by default...
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK