@geert_2, thanks for the info.
So we typically chemical vapor polish most of the prints to be used as casting patterns. As we use PLA the polishing chemical we use is Chloroform. We can achieve some phenomenally smooth prints this way, and I had always just assumed it would play a part in sealing up any small holes but upon further inspection, it doesn't really.
What is interesting is that anything printed on the UM2's generally don't have issues with small holes. Only parts printed on the UM3s which leads me to believe the heat up and cool down process between nozzle switching is introducing some small anomalies.
I was always under the impression that acetone had no major affect on PLA, and in cases where it did soften the material, it was usually due to the additives and modifiers that are used and mixed into the filament when manufactured. But I have found cloakfiend's original thread, its rather large so will sit down and have a good read through. Then probably test it out myself.
I also read through some gcode and managed to identify the m104/m109 extruder temperature change commands which appear to just be slipped in between a bunch of g1/g0 travel commands, but I don't seem to be able to identify any reasoning behind where Cura chooses to insert the temp change commands. This leads me to believe there is currently no settings within Cura to let me achieve what I want. But I am very keen to find a solution for this, at least to test results so if anyone has an idea please let me know.
until then, here's some polished eye candy for you all. (casting made from solid bronze)
Recommended Posts
geert_2 558
Not a solution, but maybe a workaround: if you would print in PLA, have you tried smoothing it with acetone or other chemicals?
See the thread and photos of user cloakfiend on acetone-smoothing of PLA on this forum: he has done hundreds of models with excellent results.
I also have done a couple of tests on colorFabb PLA/PHA: a quick brush-on of acetone tends to fill the little gaps and layer lines. But it does not fill larger gaps, nor removes features or defects like blobs and strings. See the photos.
Top orange: untreated, has small openings due to minor underextrusion.
Bottom orange: acetone-smoothed by brushing on acetone: all tiny openings are filled.
Green: silicone-impressions of the orange models: they show the irregularities well.
Left: acetone-smoothed
Center: heat-treated with heatgun
Right: untreated
Same as above. Don't use heat-treatment with a heat gun: this causes the surface to melt (which is the purpose), but it also causes the entrapped bubbles below to expand and explode, creating craters. Similar to printing wet nylon. The surface gets worse instead of better.
Don't leave PLA/PHA in acetone: it penetrates the plastic and damages it. Just a quick brush-on, and then let dry thoroughly. This little block (10mm wide x 3mm high, solid) has been sitting in acetone for about 1 hour, if I remember well.
Link to post
Share on other sites