Parts of the print are curling up  

Re: Parts of the print are curling up

With our barely adequate cooling, curling up at overhangs can be a challenge. The best way I have found to combat this is slow down the print speed during layers with overhangs (like a LOT if it is bad), and lower your bed temperature below 55 if you don’t have adhesion problems.

Re: Parts of the print are curling up

With our barely adequate cooling, curling up at overhangs can be a challenge. The best way I have found to combat this is slow down the print speed during layers with overhangs (like a LOT if it is bad), and lower your bed temperature below 55 if you don’t have adhesion problems.

I can slow layers with just overhands? How would I go about doing that?

Re: Parts of the print are curling up

And also, I ended up trying again after just simply rotating the print 90 degrees. This also ended up failing.

Re: Parts of the print are curling up

I use Simplify3d. When I see parts of the print that I know are going to want to curl, I add another process to slow that part down (for example, layers 1-24 might be normal, layers 25-33 will have steep overhangs so I have a dedicated process for those layers that has slightly lower extrusion temperature and slower perimeter speeds, and finally another process to finish up the final layers).

Barring that, you can babysit the print and slow it down via the knob when it gets to the layers with these steep overhangs.

Re: Parts of the print are curling up

Shucks, I'm not seeing any options like that in Slic3r. =(

I'm going to try printing it at like 45 max speed and see what happens.

Re: Parts of the print are curling up

Shucks, I'm not seeing any options like that in Slic3r. =(

I'm going to try printing it at like 45 max speed and see what happens.

This may blow your printer up or do something crazy. I just slapped this together from my temp-tower script, changing a few things... I have no idea if it will work.

The M220 S100 <-- DOES work. The S100 means 100% speed, S50 means 50% speed. S250 means 250% speed.
What my Gcode below does, is at the layer... around the 22mm mark, will engage the script, and slow it down to 50%.
Once the layer around 25mm is hit, it will speed back up to 100% speed.

Feel free to change the S*** numbers around... And feel free to change the 25 and 22 numbers to whatever you need. The HIGHER NUMBER MUST COME FIRST.


;BEFORE_LAYER_CHANGE
;[layer_z]

{if layer_z > 25}M220 S100
{elsif layer_z >22}M220 S50
{endif}


I have this in the "before layer change g-code." under custom G-code under the printer settings tab. 🙂

Re: Parts of the print are curling up

to adjust stuff like that you can use modifier meshes (this term should throw up a couple of threads in the forum) in Slic3r. It's slightly cumbersome but super powerful.

btw, if anyone knows a way to save a modifier configuration please let me know 🙂

Re: Parts of the print are curling up

I'd suggest, to determine if a) the problem is that the extruded stuff hasn't got enough time to cool down, or if it's b) a problem of deflected heat of the heater block to the print, print 2 of those side by side. If the curling is then less it might be case a), if there's no change, propably b).

to improve a):
- take a look at the work of JLTX. He made a great fan duct, that i'm using right now:
https://www.thingiverse.com/thing:2740613
- needless to say, put the cooling fan to the max when printing PLA
- as already mentioned here reduce speeds
- if possible add another model to give the print more off time

to improve b):
- add a silicone sock, ore something else that blocks or reduces the heat radiation emitted form the heater block to the print.
- Eventually tune speeds up so the part gets less softened by reducing the time the heater block is above the part
- and again: if possible add another model to give the print more off time

Some advises here are repeated from previous posts, but anyways, hopefully you can gain some helpful information by these impressions.

RE: Parts of the print are curling up

I know this is an ancient post, and the suggestion to minimize print temperature is spot on - but I believe there's an important clarification for what causes the curling. It is not due to insufficient cooling, it is due to the shrinking of the plastic from (Tnozzle - Tprobed location) * (Coefficient of thermal expansion for your filament). Similar to why welded assemblies warp while cooling. The hoop stresses in the circumfrence are high, as it cools they are shortening relative to the layer below they're attached to, causing it to curl upwards.

RE: Parts of the print are curling up

Posted by: @sean-obrien

I know this is an ancient post, and the suggestion to minimize print temperature is spot on - but I believe there's an important clarification for what causes the curling. It is not due to insufficient cooling, it is due to the shrinking of the plastic from (Tnozzle - Tprobed location) * (Coefficient of thermal expansion for your filament). Similar to why welded assemblies warp while cooling. The hoop stresses in the circumfrence are high, as it cools they are shortening relative to the layer below they're attached to, causing it to curl upwards.

Would the suggestion to turn down the print speed still be valid then? Or just indirectly, since running a lower speed would allow you to run a lower temp as you wouldn't need as much flow. Would a heated enclosure help?

I've been struggling a lot with curling on thin overhangs, seems to be especially bad with rainbow PLA. Running the fan at 100% seems to help a bit but I still get a lot of failures from the extruder knocking parts. I've set my z-hop to 1mm to compensate but even so, I go to sleep not knowing whether i'm gonna wake up to a mess or a completed print.