Pock marks when printing larger  

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joseph.m.silverstein
(@joseph-m-silverstein)
New Member

Hey all, 

This is my first time posting here so let me know if I'm breaking any rules. 

I'd like to ask for some advice on how to eliminate some pock marks. 

Printer: MK3 with .5mm nozzle 

Material: Esun PETG

Slicer: Simplify3D

Speed:2800mm/min

Temp:245-248

Layer height/width: .38mm/.6mm

The marks shown in the attached photo only occur when printing above .3mm height and seem to be a result of poor seam/retraction settings. 

If there is any other info you need that may help, please let me know! 

- Joe

 

Posted : 05/12/2019 10:58 pm
joseph.m.silverstein
(@joseph-m-silverstein)
New Member
In case my picture didn't show up. 
Posted : 05/12/2019 10:59 pm
bobstro
(@bobstro)
Famed Member

You are printing at roughly 47mm/s * a 0.38mm layer height * a 0.6mm extrusion width. This gives an effective extrusion rate of roughly 10.7mm^3/s. Prusa rates most PETG filaments at closer to 8mm^3/s. Any faster and you risk outrunning the ability of the E3D V6 hotend to melt and move filament reliably. This could well explain the under-extrusion you're seeing. In short: Try slowing down. With those parameters, keep your speeds below 35mm/s (2100mm/m). I'd start at 25 and work up.

Unfortunately, Simplify 3D doesn't support a Maximum volumetric speed setting like PrusaSlicer, so you'll need to manually adjust your print speeds.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 05/12/2019 11:36 pm
Tim
(@tim-m30)
Illustrious Member

And the marks you are seeing are seams, nothing to do with extrusion rate.  Change where seams are placed and you'll get better looking surfaces where you need them (I hide seams to the rear on curved parts).

ps: well, your second post shows you know they are seams... and seams can be cleaned up, but that will take a lot of tweaking. But K-factor, jerk, acceleration, z-lift, retraction, all of these interplay to make good seams.

This post was modified 3 months ago by Tim
It is always wise to get more than one opinion......
Posted : 06/12/2019 5:58 am
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