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How to keep corners good when printing fast?
Posted: Sat Jun 16, 2018 10:45 am
by WhiteHare
Here's a test object that I'm printing at 3000mm/min using a 0.8mm volcano nozzle and PETG filament and linear advance K=20. Layer height is 0.4mm and extrusion width is 0.96mm. The corners look acceptable to me:
However, if I increase the speed to 4000mm/min, the rest of the model stays fine, but the corners look terrible:
What can I do to keep decent corners a higher speeds?
Re: How to keep corners good when printing fast?
Posted: Sat Jun 16, 2018 1:03 pm
by MasterFX
This looks for me more like a cooling problem. Did you turn your fan on? I mean 66mm/s isn't that fast, but since you are printing only perimeters (or Vase Mode) each layer takes not that long, and therefor the filament from the layer below isn't cooled down enough.
Re: How to keep corners good when printing fast?
Posted: Thu Jun 21, 2018 5:19 pm
by zemlin
I'd call that going too fast.
You might improve the results by increasing the nozzle temperature which will reduce the viscosity, elasticity, and tensile strength of the extruded bead and might improve the layer bonding.
Re: How to keep corners good when printing fast?
Posted: Fri Jun 22, 2018 7:05 am
by wirlybird
It doesn't seem to be exceptional fast but one thing is that PETG doesn't like to be printed fast. I am guessing you are on a MK2 or MK3?
I normally print PETG at a max of 40mm/s on my MK2.
Re: How to keep corners good when printing fast?
Posted: Fri Jun 22, 2018 12:11 pm
by TheBum
wirlybird wrote: ↑Fri Jun 22, 2018 7:05 am
I normally print PETG at a max of 40mm/s on my MK2.
Same on my Snapmaker. and even then the corners are a little rough.
Re: How to keep corners good when printing fast?
Posted: Fri Jun 22, 2018 1:59 pm
by dkightley
It doesn't seem to be exceptional fast...….
I'd agree there......but having looked at the nozzle size I begin to wonder if the hot end is not coping properly with the amount of plastic it is being asked to heat and extrude. I think its a flow rate issue as opposed to a speed issue!
Re: How to keep corners good when printing fast?
Posted: Sat Mar 09, 2019 9:44 pm
by jgwinner
Did you figure out what it was?
== John ==
Re: How to keep corners good when printing fast?
Posted: Tue Mar 12, 2019 11:04 am
by zemlin
Coming back to this topic with some additional experience, I'd also suggest running an extrusion width about 1.2 x of the nozzle diameter. The plastic expands naturally when it exits the nozzle. Trying to maintain an extrusion width equal to the nozzle diameter requires the stream to be stretched a bit and can pull in on the corners.
Re: How to keep corners good when printing fast?
Posted: Thu Mar 14, 2019 9:26 pm
by jgwinner
Thanks. I just checked, and for some reason my profile was at 100% of the width. I changed to "auto" and it set it at .48mm (vice .4mm, same size nozzle)
== John ==
Re: How to keep corners good when printing fast?
Posted: Fri Mar 15, 2019 8:52 am
by zemlin
jgwinner wrote: ↑Thu Mar 14, 2019 9:26 pm
Thanks. I just checked, and for some reason my profile was at 100% of the width. I changed to "auto" and it set it at .48mm (vice .4mm, same size nozzle)
== John ==
Let me know if that helps. My reply was somewhat speculative. Confirmation would be good.