H2C print issues tall thin object

Euresko · February 6, 2026, 8:51pm

I’m printing a mini Zelda sword, about 185mm tall. It’s fairly thin and tall, which I know could be an issue. I’m having issues. The tip of the sword will melt into a ball. Sometimes the small hilt parts get knocked off, or the handle and supports get knocked down, and have to cancel the print. I have ran the full printer calibration and used the vision encoder plate a few times. Whole the H2C has issues, my P1S with hundreds of hours prints it flawlessly as shown in the photo. Left is from my P1S with a 0.4 nozzle, same filament (printed flawlessly) and right is H2C (glob at the top). I’m using the same roll on each printer.

Using the H2C with 0.4 left nozzle and Bambu matte PLA, that was dried. Both printers are using the latest official firmware and slicer (2.5.0.66). I load the STL, added auto tree supports and hit print. After 15 attempts on the H2C, it will not print correctly, even once. Seems like the nozzle is dragging around in the filament and balls it up on the tip on the H2C. Not sure what is causing this. To troubleshoot I’ve tried slowing down various settings, putting the H2C in silent mode, leaving the door open, increasing fan speed, increasing print speed.

Someone on Reddit replied to my question and suggested I enable smooth time lapse, which makes it print a prime tower and move the point head to snap. A time lapse photo n they thought maybe doing this would slow it down more and let the previous layer cool more. That did not help. I also tried printing a cylinder near the sword so the printer would have to move and go deposit some filament elsewhere and come back to the sword, and that was not helpful either.

I have even gone through the slicer for P1S settings and made them the same over on the studio session for the H2C. I also have uninstalled the slicer, deleted all settings, rebooted, reinstalled the slicer, and when it asked to download my personal configs and stuff, I said no. So I have tested with bone stock H2C settings as I possibly can. I still get a ball on the top of the sword blade.

What could I possibly change to get the tip to print correctly, or address issues of parts of the hilt getting knocked off the supports, etc. I know the plate is clean, as that has been washed with warm water and soap. I don’t print a lot of PETG, and haven’t done PETG recently.

I have also opened up a support ticket with Bambu.

sneezr · February 7, 2026, 6:58am

Could you share a link to the model to look at it?

Gerrit · February 7, 2026, 7:30am

The issue with the tip is a common cooling issue.

The layer time is getting too short and causes this behavior.

There are 2 things you might want to look at. And that is minimum layer time, but more importantly the minimum speed in that section. Because that overrules the minimum layer time. It also helps to have your part cooling increased to the max for that.

You will find all those settings under the cooling tab in the filament settings.

waynejohns1973 · February 7, 2026, 3:01pm

Or put a basic square column at the same height as your model/sword on the opposite side of the build plate.

Set it to 5% infill and 1 wall.

The time it takes to go over there, print a single layer, then return will be sufficient to allow your main model - in this case the sword - to cool and stop the issue altogether.

This will work for any tall thin models.

RocketSled · February 7, 2026, 3:39pm

This happens because the model is tall and thin and that means it can wobble when the extruder tries to extrude on it. The nozzle and extruding plastic pull the top of the print along, a little behind the nozzle’s position, as it moves.

Fix it by slowing down a lot at these layers, or painting some intermediate supports connecting to the sides to stabilize the print. You don’t need to go to the top, 2/3rds of the way will be enough.

You might also need to bump the flow up a tiny bit.

Euresko · February 7, 2026, 6:16pm

I opened a ticket with Bambu but asked them to close it after doing more digging, since I came up with a solution I think.

There does not seem to be anything different about the slicer results when you look at it line by line around the tip area, comparing P1S vs H2C, at least not that I could tell.

The issue was that the top of this model when sliced is printing solid material about 50 layers down from the tip. This concentrates the heat and starts to soften it and after about 10 layers it’s a lost cause and will just form into a ball, instead of a sharp sword tip.

The fix for me was a few things:

Attached screenshot below: Global > Strength > Advanced. Changing those settings as I have shown seemed to help thin out the walls at the tip, instead of being solid it thined to be 2 walls like I had set in the “Strength > Walls > Wall loops” setting. The rest of the model has 2 walls, but the tip would form a solid layer and then just keep building on that for the last 50 layers
Other settings screenshot: Global > Strength > Top/bottom shell layers. Changed these settings to what I am showing in the other screenshot, not sure if that helped or is not necessary, but was attempting to thin my top surface, thinking that was where my problem was at.
In an effort to make the tip as lightweight as possible, to avoid heat soaking it from a spinning nozzle and solid infill, I added a modifier cube to the tip, and was able to eliminate the gyroid infill completely, so all it does now for these last 50 layers is built 2 walls for the tip, nothing internal at all. The results were my attached samples, the blue sword tips.

Once these settings were applied to the tip, the top surface of the hand guard/hilt was too thin and was showing holes. To fix that issue I applied another modifier cube and assigned it some wall settings to just infill each side of the hilt and now it makes a solid surface a few layers deep, instead of a thin top surface that looked like swiss cheese.

After all these settings were changed, my small sample blades printed on the H2C without issue. I then printed the full sword with default tree supports and changed nothing else (no fan, filament, door still closed, etc), everthing else in my previous test and final results were the same with Bambu PLA. I then used Bambi PLA Silk+, did not change anything else besides the filament in the slicer, and that worked awesome as well. During and after my testing I had not altered the PLA settings for either printer, just used the default settings Bambu has in the slicer. On both before/after tests on either printer the door was closed, as leaving the door open and testing did not give any better/worse results.

Hopefully this helps someone else that is struggling to get fine details with the H2C where the nozzle sits and prints for too long.