Help with apparently too hot printing
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I thought I would run this past you all to see what you think;
This model is printed upside down with PLA, 200 nozzle temp, 80 bed temp.
The object is hollow but has a fairly thick top (bottom in printing position).
What you see here is good printing for thickness of the top but then it all goes to pot.
The corners especially are behaving as if there wasn't enough part cooling happening (cooling is at 100% but is at a fairly shallow angle across the model). The walls are 45 degrees, infill is 20% and wall thickness is IIRC 4 mm with 3 walls. The inside of those corners is printed just fine, it's only the outside that is messed up. Outer wall speed is 35 mm/sec but inner wall speed is 50 mm/sec.
It is only the angled section that is messed up, the straight up and down section is just fine.
I tried a different roll of PLA - same outcome..Thoughts ?
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On further examination, one corner is perfectly fine, the other three that are messed up show signs of the print curling up at the corners during printing.
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@jens55
How big is the part....?
Reduce bed temp....I have always printed pla at about 60°C
Are you shure that the fan works with the correct voltage?
Use a cooling option in the slicer to reduce print speed in smaller areas.
Use a sock....
Print two of them with a distance. (I have had similar problems when the heating block is always above the part.)(UTC+1)
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@diy-o-sphere
Maybe another possibility is to set the acceleration higher, so that the nozzle goes faster around the corners ...(UTC+1)
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@diy-o-sphere said in Help with apparently too hot printing:
@jens55
How big is the part....?80 mm by 80 mm by about 50 mm tall
Reduce bed temp....I have always printed pla at about 60°C
Will give that a try although bed adhesion (I use straight glass) could become an issue.
Are you shure that the fan works with the correct voltage?
Yes, I verified that the fan (blower) turns
Use a cooling option in the slicer to reduce print speed in smaller areas.
I would if there was a 'smaller area' but this thing is not small. Also, remember that the straight edges on the model print just fine.
Use a sock....
I will check but I think I have a sock installed .... but good call!
Print two of them with a distance. (I have had similar problems when the heating block is always above the part.)
Not sure what to say here ... I am getting more and more convinced that the fact that I am printing a 45 degree tilted wall and there is pronounced lifting of the corner are somehow to blame.
For now I will verify that I am using a sock and I will reduce the bed temp to 60C after the first few layers are down.
Thanks for your thoughts !
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@diy-o-sphere said in Help with apparently too hot printing:
@diy-o-sphere
Maybe another possibility is to set the acceleration higher, so that the nozzle goes faster around the corners ...The problem here is that this is a bed slinger with a 500x500 mm bed and is already showing all kinds of artifacts because of vibration. I can however try printing the exterior wall at full speed rather than the reduced speed I normally do for outside walls.
Thank You ! -
@jens55 said in Help with apparently too hot printing:
Not sure what to say here ... I am getting more and more convinced that the fact that I am printing a 45 degree tilted wall and there is pronounced lifting of the corner are somehow to blame.
I have also found that the tilted walls are more difficult to print in this direction especially for certain filaments.
But rather unusual problem for PLA and this size
I would consider reducing the print temperature a bit as well -
The first reprint was with outside wall speed increased from 35 mm/s to 70 mm/sec with no apparent difference. I am now printing with an initial bed of 90 C (as before) but then reducing the bed temp to 60C (instead of 80C) I have also reduced printing temperature from 200C to 190C.
So far, there seems less bending up on the corners but it is pretty early in the process to tell for sure. -
Just had another look - three corners seem ok but one corner is still curling up. This is a 6 hr print but I will abort it at maybe 2 hours which should cover the sloped section and I will report back.
I am getting concerned with layer bonding by printing this cold ..... -
@jens55 be sure that your minimum layer time is at least 30 seconds. If it still curls, increase it (make the printer slower). PLA need a lot of fresh air and maybe your blowers are not strong enough. Also bed temp is way too high! On which surface are you printing? i have a plain PEI and print at 45°C from first layer. This helps a lot with cooling.
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@jens55 Would definitely agree with the others that 80deg is probably too hot for PLA bed temp. Hairspray my friend! Either that or get a PEI sheet
Have you checked how much your cooling fan is actually running during the print? If it's not at 100% when doing those overhangs then probably worth bumping up the slicer settings! I made this mistake when setting up my delta, then realised my fan was only running at 20% when I needed 100%...
Also, have you tried using smaller layer heights (for the overhang bit at least?) . Lower layer heights generally allow better overhangs because the overhang each layer does (in mm) is less. Ther other advantage here is that you are putting in less hot plastic for each nozzle pass so it can cool down quicker.
Also on layer adhesion, I've found most PLA's work even down to 180deg, so wouldn't be too scared of going lower. Unless this is a structural part, in which case, PLA might not be your best choice anyway...
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@engikeneer said in Help with apparently too hot printing:
@jens55 Would definitely agree with the others that 80deg is probably too hot for PLA bed temp. Hairspray my friend! Either that or get a PEI sheet
I hate hate hate putting any goo of any kind on my print bed. It isn't necessary, makes a mess and usually you can see it on the print surface that touched the bed.
The current print is sticking well at 90C for the first layer ad then dropping to 60C. Actually that print, which is still running, is doing very well and I decided to let it run for the entire job rather than aborting it half way through.Have you checked how much your cooling fan is actually running during the print? If it's not at 100% when doing those overhangs then probably worth bumping up the slicer settings! I made this mistake when setting up my delta, then realised my fan was only running at 20% when I needed 100%...
I verified that the blower was turning but don't know how to verify that it's at 100% (Duet reports 100%)
Also, have you tried using smaller layer heights (for the overhang bit at least?) . Lower layer heights generally allow better overhangs because the overhang each layer does (in mm) is less.
Good idea, I will keep that in mind!
Also on layer adhesion, I've found most PLA's work even down to 180deg, so wouldn't be too scared of going lower.
It will be interesting to see how a190C print turns out.
Thanks!
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@jens55 Fair points!
RE the fan setting, I was meaning check what your slicer is setting it to (PrusaSlicer will colour the model with the fan speed for each layer to show you, guessing others will do the same). If DWC says 100%, then probably is 100% though!
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The next print sample is finished. The outcome is MUCH better than before but one out of the four edges is still dud.
Here is the bad edge and you can see just a hint of the edge lifting (remember this is printed upside down so 'lifting' here means 'edge pulling down' in this picture.
This is one of the other edges
In my mind, these results confirm that things were printed too hot but I am surprised that even 190C seems too high.
Next I will print at 185C to see if I can get the last edge 'fixed'
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@jens55 i don't understand why you ask for help and then do the same mistakes after everyone told you that 90°c is too high for PLA. You might check out what glass transition temperature is and how much it is for PLA.
However remember that your cooling fan is not cooling every edge the same way. Turing the nozzle temperature too low will not help with that because the bed will keep the part too hot. Try putting a fan in front of your printer pushing fresh air: maybe your part will be brittle but you will see how much the surface finish will improve and use it as reference for further tuning.
If you don't have it buy a pei sheet or use blue masking tape and print the same gcode with 30°c bed (or also cold). We all faced that type of issues and the problem is always that PLA is not a material that likes 60°C temperature and high speed print.
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@mikes said in Help with apparently too hot printing:
We all faced that type of issues and the problem is always that PLA is not a material that likes 60°C temperature and high speed print.
Curious.
I have always printed regular PLA on a 60 degree bed and never had an problems.
But I do print the first layer at a slow speed (15 mm/s) then moving up to 60 or better.
Frederick
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@jens55 my guess I that that bad corner is your seam? Looks like there I bit of over extrusion at the very start of the first line of the first layer, then some of ripples at the end. Might be worth trying to tune PA and retraction a bit more, or use the P1 jerk policy.
Or alternatively, put the seam in the middle of one of the edges and/or set hour slicer to print the outer perimeters last?E3D TC with D3Mini and Toolboards.
Home-built CoreXY, Duet Wifi, Chimera direct drive, 2x BMG, 300x300x300 build volume
i3 clone with a bunch of mods -
@mikes said in Help with apparently too hot printing:
@jens55 i don't understand why you ask for help and then do the same mistakes after everyone told you that 90°c is too high for PLA. You might check out what glass transition temperature is and how much it is for PLA.
Somebody seems to have a bad day .... sorry, hope it improves!
For the record, I have taken all the advise people have given me and adjusted my print accordingly. I was printing at 200, went down to 190 (this last set of pictures) and am presently printing at 185
I am not sure were the 90C comes from that you are talking about but the only place that comes in is for the bed temperature for the first layer and this is nowhere near where the issue occurs.However remember that your cooling fan is not cooling every edge the same way. Turing the nozzle temperature too low will not help with that because the bed will keep the part too hot. Try putting a fan in front of your printer pushing fresh air: maybe your part will be brittle but you will see how much the surface finish will improve and use it as reference for further tuning.
I did a print with 60C bed temp (all but the first layer) - no difference.
If you don't have it buy a pei sheet or use blue masking tape and print the same gcode with 30°c bed (or also cold). We all faced that type of issues and the problem is always that PLA is not a material that likes 60°C temperature and high speed print.
As I said, there was no difference in the nature of the problem when I dropped the bed temperature to 60C. There was a large improvement in the issue when I went from 200C to 190C nozzle temperature!
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@engikeneer said in Help with apparently too hot printing:
@jens55 my guess I that that bad corner is your seam? Looks like there I bit of over extrusion at the very start of the first line of the first layer, then some of ripples at the end. Might be worth trying to tune PA and retraction a bit more, or use the P1 jerk policy.
Or alternatively, put the seam in the middle of one of the edges and/or set hour slicer to print the outer perimeters last?Now that is a really interesting thought and one well worth digging into. It would certainly explain why 3 edges are good and one is bad!
Thank you, I will look into that ! -
@jens55 60°C is still high for normal PLA. If you need these type of temperature try using some filament that is composite for take the glass transition temperature higher which is around 60°C for PLA. If you keep the part over that temperature overhangs will be a lot harder to print.
I've found some cheap PLA that cost around 11€/kg and it is much more prone to curling that for example colorfabb PLA/PHA.
10 degress less on the nozzle would change the curling behaviour only a little because the real heat reservoir in this case is the bed.Also as already suggested try randomize the seam position to, at least, know if also it is making the edge worse. If that is the case so try to check retraction settings and PA.
Just for debugging it i see a lot of wobbling on your print. Are you sure you are not printing too fast/too much acceleration?
