Ironing: black traces (Durabio)
I am trying to print a simple frame with a surface which shall be as smooth as possible using Durabio material (similar to PETG in terms of look and fluidity but does not like cooling and needs higher bed temperature).
For ironing, I got best results with 30% flow rate (if lower, you sometimes get small holes in the surface), spacing 0.1mm and speed 15 mm/s, printing temperature 225°.
I was able to basically completely eliminate stringing and there are no burning marks on the print (which are brown with this material). However, in about 2/3 of all prints, I get small black traces during the ironing phase. We have filmed the print and even sat near the printer with some colleagues during the whole ironing phase to see why it happens: nothing, no strings, no excess material. Also super-cleaning the nozzle (outside) did not help.
Does anyone have an idea why these black traces are developing and how to avoid them?
Thank you so much for your ideas in advance!
For the smoothest possible surface use a smooth PEI sheet and print the other way up.
Especially with ironing, the head builds up a layer of burned varnish. Clean it off with a great filament head cleaner before every print - and if you need to, mid-print - but I think mid-print would be overkill. Agree w/Diem - use the sheet to your advantage.
So just dirt? Trying with a brand new MK3s+ which has just arrived. I will let you know!
No, not dirt. Burnt filament.
So you do not mean residuals (burned filament) around the nozzle but inside the nozzle?
Probably not inside. Move your print head up to around 150, take a flashlight and look at the nozzle. Is it shiny brass? Or is it black and gunked up.
I was really optimistic but unfortunately this happens in the same way with a brand-new printer with perfectly clean nozzle. Any other idea what may cause this effect?
When you iron the extrusion rate is slowed right down and filament stays in the hot zone for much longer.
So you suggest trying to increase ironing speed to reduce the time of hot exposure?
Personally I've never seen the point of ironing, better to sand fill and paint. If I want a smooth unpainted finish then inverting and using the face in contact with the smooth PEI sheet is the obvious method.