I wanted to print an arc [1] and had the problem that the nozzle hit the model. I also observed that the nozzle bent the model away and printed in the air instead of printing on the previous layer. Here the standard profile (0.2mm) was used.
To see if it was due to my design, I had an overhang test printed, using the same material and print profile [2]. The print worked, but you can see in the pictures that even at small angles of the overhang there are errors in the print. Is this normal or should it look better?
I was present during this print and filmed the end [4]. Here you can see how the nozzle hits the print (0:41, 0:51), which leads to the visible loops in image [3].
After that I tried to print with the profile “0.12 fine” and variable layer height optimized for quality [5]. But I had to abort this print because, as in [1], the model was bent away and printed in the air instead of on the previous layer.
Filament is PETG from Bambu which was previously dried overnight and dried in the Sunlu S2 during printing. The door is closed, the lid removed.
The P1S is my first printer and I do not know if this is normal and I already have to print the overhang test with support or these filigree overhangs are generally a problem and you have to expect failures? Can you change settings here such as slowing down the print head when repositioning?
Which one. My design [1] or the overhang test [2]?
You’re printing a handful of layers onto air. Have you tried printing with support?
No. I was confused, because even with support enabled in BambuStudio, it wouldn’t add support in the problematic part of [1]. Only for the very top bridge.
Your design. It would be much better to print it in two pieces so you can lay the arc/hoop flat on the bed. It will actually be stronger that way as the layers are on the same plane as the arc.
If for some reason you can’t do that, slow your printing speed right down. Second use supports and adjust the angle at which supports start. You could also manually paint in the area that needs support.
I expect to see some quality loss without supports on anything over about 50°. The exact attainable overhang depends on the model and settings. Your test print looks very good up to 50° and still decent at 60°.
Besides the fact that there is no support to hold the filament while it cools, the sticky filament can drag tall thin prints to the side as the nozzle moves. Additional support may need to be added to stabilize model, then cut away afterward.
The test model in you picture is used to see how much of an angle can be used before support is needed. As a new user, I find using that result a little confusing, but apparently you need to subtract the angle of the last good result from 90° and enter it as the Threshold angle in support settings. Here is the test model with tree supports enabled and threshold angle set at 30°:
If supports are not being generated automatically during slicing, you can manually paint them where needed:
Your design. It would be much better to print it in two pieces so you can lay the arc/hoop flat on the bed.
I started with that, but had the same problem when printing the base of the arc [6]
If for some reason you can’t do that, slow your printing speed right down.
I tried this yesterday by setting the “gap infil” and “travel” speeds to 60 mm/s, which is the same speed as the default setting for <25% overhang. Here I had the same problem at the same height as in [5]. Visible in [7].
The test model in you picture is used to see how much of an angle can be used before support is needed. As a new user, I find using that result a little confusing, but apparently you need to subtract the angle of the last good result from 90° and enter it as the Threshold angle in support settings.
Thanks for clarification. Both of you suggested to add support, I will try this next, thanks!
I now tried to print it with support by setting “Threshold angle” to 60. The nozzle still interacts with the arc https://youtu.be/ny97hP7bHMk
I thought it works out, because the arc moves, but just a little. Some minutes after I stopped the camera the nozzle hit the arc again and I heard a crack in the model. There the nozzle broke the left arc from the base ring, you can see it leaning to the right in [8]. It printed the next layers on the support instead of the misplaced arc part [9] and I stopped the print.
You could print this as two different parts and then snap/glue them together. That would allow you to lay the arc on its side – where it could easily be printed.
I know. The question is not how to print this. The question is: Is it normal that the nozzle hits the model? E.g. when you print this overhang test by bruh3d - MakerWorld
Attempting to print models like this in mid-air is definitely not normal. Perhaps the layers near the top are not supported well enough and aren’t printing in the proper location – causing the nozzle to touch more while printing the layers beyond that?
What happens when you print the overhang test with tree support like this?
It looks like the small base of tapered side is not providing enough support, which might let it rock back and forth as it prints. The ever-wider and taller layers on the top pull in an arc, until the corner rises higher than the nozzle tip, causing a collision.
I like tree supports which usually use less material and have less contact area on the print. That leaves fewer “scars” and are less work to remove.
Try “tree(auto)” supports in the “Tree Slim” style. Check the box for “On build plate only” and try manually painting more supports at a few spots on the skinny edges. “Support x/y distance” of about 0.10 or 0.15mm should keep the support (green) slightly off the model (red) but still restrict rocking. One single dot painted on each side produced this quick and crude example:
My biggest problem was that I could not understand how the nozzle can drag the model, since it is on the same layer. Therefore, it is a very good and obvious explanation for this circumstance, that by the mobility the part comes higher and has even chance to collide with the nozzle. With this I can make sure that overhangs have a big enough base to give the whole thing more stability. Thank you!
I have a dragging issue when there is a lot of infill, the nozzle drags along as it’s laying down the filament. Very discouraging that it hits so much, that it knocks prints off the bed.
Did you find a solution?
It’s happening to me too, only on a particular print that is 100% infill.
I notice it kind of builds up a small mound of material and that’s where it hits/drags.
Sounds scary like it could mess something up.
I did the PLA calibration and still did it.
I now upped the by temp 5* and it improved slightly…
This nozzle hitting the prints and the supports is a real mess. First, if using the 100% infill, which is common for small or “fragile” items, the OS will not let you choose anything but the grid infill pattern. The Grid pattern is notorious for causing nozzle strikes, especially with Ironing layers. Change to less infill to choose a different infill pattern. Second, this occurs in both the A1 and the X1. [I have both.] It is a mechanical problem. I have even tried to get the nozzle to “Hop” at the walls to no avail. So I don’t use grid anymore or 100% infill. Some support uses grid as a default and the nozzle takes them out especially toward the rear of the build plate and at Z >10 mm. [PEI exclusively in my case.] Oh and I just updated 2 days ago to the latest versions for A1 and X1 and the problem persists.
Oh wow. Having that happen sucks. Thats been my fear 6 hours into a print and boom. Thanks for letting me know. Guess I won’t be doing using that option again, that sucks as I wanted more weight to the object.
So, even using 99% so you can then select Gyroid for example still causes nozzle strikes?
