Additional cooling for Prusa MK2?

XViper

Gawd
Joined
Aug 24, 2012
Messages
836
I think my prints are curling from not enough cooling. Is there any adverse effects if I just put a box fan blowing on the print? Should I turn off the bed heating after a few layers? Large prints aren't successful with PLA unfortunately.
 

XViper

Gawd
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Aug 24, 2012
Messages
836
Ok a bit of a report. I noticed that it will warp if I have the fan blowing on it in the first 2 layers. After the first few layers, the fan helps massively. I'm able to print large objects now on the bed. I think it's due to the fact that the printer is sitting in an enclosure and even with the door open, it seems to trap the heat and thereby causing curling from the overhangs.

Might attempt to print the Storm Trooper helmet this weekend.
 

WheresWaldo

Limp Gawd
Joined
Dec 7, 2004
Messages
183
Ok a bit of a report. I noticed that it will warp if I have the fan blowing on it in the first 2 layers. After the first few layers, the fan helps massively. I'm able to print large objects now on the bed. I think it's due to the fact that the printer is sitting in an enclosure and even with the door open, it seems to trap the heat and thereby causing curling from the overhangs.

Might attempt to print the Storm Trooper helmet this weekend.
Normally there should have been more information provided to give you an accurate assessment of the issue, like what filament, what bed temp, etc. But typically you would not want parts cooling on the first several layers to insure proper bed adhesion. Also some filaments (ABS for example) do not really like parts cooling if you want maximum intralayer adhesion. It isn't a hard and fast rule, but a typical setup.

Even if you use a different slicer, look over the visual troubleshooting guide at https://www.simplify3d.com/support/print-quality-troubleshooting/
 
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Normally there should have been more information provided to give you an accurate assessment of the issue, like what filament, what bed temp, etc. But typically you would not want parts cooling on the first several layers to insure proper bed adhesion. Also some filaments (ABS for example) do not really like parts cooling if you want maximum intralayer adhesion. It isn't a hard and fast rule, but a typical setup.

Even if you use a different slicer, look over the visual troubleshooting guide at https://www.simplify3d.com/support/print-quality-troubleshooting/
A lot of slicers have ramp up values for fan speed. Usually on the cr-10 I don't use cooling for the first 10 or so layers, then slowly ramp it in. Cooling is usually most helpful for bridging, but it is applicable in other spots as well. I'm an intermediate knowledge printer, some more advanced folks may have other thoughts.

Not sure what your bed is but I use 60C heating and purple gluesticks....it may be too much adhesion for pla...
 

XViper

Gawd
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Aug 24, 2012
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Oh I thought I posted it. I'm using PLA. It's funny but I generally only print in ABS. Enclosures are bad for PLA. I'm using Polysmooth PLA filament. Extruding at 205, bed at 60. PLA is an adventure for me. I'm using the printers for fun as work is super light at the end of the year. Going to spend time making small toys for the kids.

For ABS, I generally don't use cooling however turning on the fan to like 20-30% for layers after the first few improves the surface of ABS. I printed a cone piece that me and my brother designed and it needs the fan otherwise, the layers would collapse on each other. ABS is printed in a custom acrylic box that maintains heat without drafts. Prints come out perfect for that. Extrusion temp at 255 and 110 bed temp. I have a Prusa Mk3 and I have 4 Mk2's.
 
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I don't know that it's that enclosures are bad for PLA. Most people do that as an upgrade to cr-10s and the like. I haven't done any ABS printing on mine, but PLA will warp off glass if the speed is too high, there is too much cooling, or not enough gluestick. Just what I've found.
 

XViper

Gawd
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Aug 24, 2012
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PLA just doesn't like heat. Both ABS and PLA will shrink to a certain extent, ABS more so. I don't have issues with PLA on the first layer. It's the overhangs that curl up and my print head just hits it and all hell breaks loose.

I've heard a lot of good things about CR-10s. It's supposed to be crazy easy to assemble.

Also, I don't use gluestick for either ABS or PLA. Try using a PEI sheet. Works awesome.
 

WheresWaldo

Limp Gawd
Joined
Dec 7, 2004
Messages
183
With PEI sheets, you can print PLA with no bed heating, but I generally warm the bed to about 40°C anyway. If your prints stick too well, you can use a release agent. My goto release agent is the dollar store hairspray helps with adhesion but releases completely when cooled.

Cooling fans on PLA work well to prevent the curling on overhangs, also setting the print from inside to outside can help with any curling issues.
 

XViper

Gawd
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Aug 24, 2012
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836
So I have a large bust print that will roughly take about 12 hours to complete. For reasons unknown to me, it always fails. It's constantly layer shifting. I caught it a few times and it's due to the printer head knocking some part of a print that curled. I'll post a pic when I can.
 

WheresWaldo

Limp Gawd
Joined
Dec 7, 2004
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183
You might need to adjust slicer settings to introduce a vertical hop when making moves,

S3D = Edit Process > Extruder > Retraction vertical lift
Cura = Settings > Travel > Z-hop when retracted
Matter Control = Advanced Settings > Filament > Retraction > Z Lift

Alternatively, you can find the setting to avoid travel over printed areas. It makes the print take longer but won't drag the nozzle over what you have already printed.
 

XViper

Gawd
Joined
Aug 24, 2012
Messages
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I've tried vertical lift and it didn't work when I tried it before. Someone suggested that it could be excess heat on the control board so I took the printer out from the enclosure and restarted the print. I've made sure vertical lift was enabled so lets see if it fixes it. I'll also look into the avoid travel over printed areas.
 
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I'm going to throw this out there are food for thought, just in case helps. I run my cr10 off a pi3 with octoprint. I was getting the nozzle hitting the print a few hours in for no seemingly possible reason. Long story short, a more powerful adapter into the pi fixed the issue. Maybe you have a weird power supply issue into the control board of your mk2? I realize you don't have the problem with ABS...but who knows, may be something to check.
 

XViper

Gawd
Joined
Aug 24, 2012
Messages
836
I'm going to throw this out there are food for thought, just in case helps. I run my cr10 off a pi3 with octoprint. I was getting the nozzle hitting the print a few hours in for no seemingly possible reason. Long story short, a more powerful adapter into the pi fixed the issue. Maybe you have a weird power supply issue into the control board of your mk2? I realize you don't have the problem with ABS...but who knows, may be something to check.
That's funny you mention that. When I took it out of the enclosure, I put the print on the SD card and to my surprise, it printed just fine. I also increased more heat so I'm not sure what fixed it.
 

guitarslingerchris

Failure is just success rounded down
Joined
Oct 29, 2004
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I realize this thread is a bit old but I upgraded my parts cooling fan on my MK2S to a nicer Sunon fan from mouser and it is night and day performance with overhangs. I do also run a modified nozzle but the combination has changed everything about the ability for the printer to do steeper overhangs and just overall higher quality and lower noise.

https://www.mouser.com/ProductDetail/sunon/mf50151vx-b00u-a99/?qs=EU6FO9ffTwfWIV5p3irB3g==&countrycode=US&currencycode=USD
https://www.thingiverse.com/thing:2276997

I actually lost parts of my X axis due to a failed ABS print and had someone print up some replacements for me and they suggested this specific nozzle so I had them print me a couple and gave it a try. Out of the THIRTEEN variants I have tried this nozzle has given me universally better results and it is improved further by that fan.
 

XViper

Gawd
Joined
Aug 24, 2012
Messages
836
I realize this thread is a bit old but I upgraded my parts cooling fan on my MK2S to a nicer Sunon fan from mouser and it is night and day performance with overhangs. I do also run a modified nozzle but the combination has changed everything about the ability for the printer to do steeper overhangs and just overall higher quality and lower noise.

https://www.mouser.com/ProductDetail/sunon/mf50151vx-b00u-a99/?qs=EU6FO9ffTwfWIV5p3irB3g==&countrycode=US&currencycode=USD
https://www.thingiverse.com/thing:2276997

I actually lost parts of my X axis due to a failed ABS print and had someone print up some replacements for me and they suggested this specific nozzle so I had them print me a couple and gave it a try. Out of the THIRTEEN variants I have tried this nozzle has given me universally better results and it is improved further by that fan.
Awesome. Noise doesn't bother me but the ability to do steeper overhangs is awesome. The comments on Thingiverse say it melts. I use a sock on mine though. Hope it fits.
 

guitarslingerchris

Failure is just success rounded down
Joined
Oct 29, 2004
Messages
6,533
Awesome. Noise doesn't bother me but the ability to do steeper overhangs is awesome. The comments on Thingiverse say it melts. I use a sock on mine though. Hope it fits.
I haven't had mine even begin to melt yet and while the fan upgrade is new the nozzle I have been using for almost 10 months now. Mine is printed in ABS though, not PETG or PLA like I suspect others do.
 
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