eSun ePA-GF - weird hue changes on layers
Average humidity here (Canberra) ranges from 35% to 64% so not as bad as the coast but still a problem in the wetter months. Those cabinets look great but each one costs almost as much as two Prusa Mk3S. I'll have to get a bit more work before I can justify one to myself.
....and that the rub. The "utra dry" ones are very expensive (though they do have a model half the size for a bit more than half the price). I also tested the cheaper sub A$1K cabinets and they don't drop the humidity enough to be worthwhile for stuff like ePA, PEEK etc as they only get down to about 30%RH
Ultra Dry seems the only sensible way to go. I'll add one of those to the long term purchasing list.
Here's an image of the final print. The one on the right is the original print with the ePa-GF filament having spent about 12 hours in the dehydrator. On the left is the print with filament having spent 36 hours in the dehydrator. The one on the left had supports off in the ribbed section and less infill otherwise the same settings. I think another 24 hours in the dehydrator would get a consistent print. Next time I'll try three days drying. I am very pleased with the second print. The filament has bridged quite well and seems very strong. Supports definitely require tuning for easy removal as the material is very strong and adheres very well.
For reference, print size is about 150 x 60 x 170mm in x,y,z. Settings: 0.6 nozzle, 0.3mm layer height, bed temp 90 degrees C and nozzle 250 degrees C. I used Simplify 3D to slice as I like its supports better than Prusaslicer. I copied the filament and print settings over from Pruserslicer's Taulman Bridge settings. Final print used about 300g of material.
Nice - it now look much better... Mimics what I saw with mine as well;
- Out of the packet: Is cream and has a balsa wood type finish with poor bridging and lots of stringing
- Getting Dry: Harder, no stringing, better bridging, more yellow, but with that weird colour banding
I'm surprised that even after all that time you had it in the dehydrator it still has the banding. The only other thing I did (apart from store it in the 0%RH Cabinet) was give it hits in the Vacuum Chamber. At least these can be inexpensive. I also saw a some discussion about using the chambers as storage as they will hold a vacuum apparently for a long time and fit 4 - 5 spools for a mid size one. The cheap e-bay pumps are fine but they really need to be a 2 stage pump to be strong enough.
I'm waiting to see more details on this https://amtechniques.com/ when it hits Kickstarter. Not that I plan to buy it (at that projected price) but I'll be interested to see what details come our from Vacuum Drying, I'm hoping to see some stats on time & dryness vs just using hot air. I'm thinking that it could be a better approach in general to filament drying but I've not had the time to test it myself.
Having a closer look at your latest pics you can see the yellow bands (fully dry) look great. The lighter bands (less yellow) still show some fussiness on the top edge of the slopes (similar to the first print).
Yep, It must have been pretty wet. The eSun bags are obviously not sufficient to prevent moisture ingress. I'll do some test printing next time and won't start a full print until I am happy with the dryness of the filament.
That looks like a great idea, but he price is a bit out of reach for the hobbyist. I'm starting make some money from printing but not enough yet to justify that. If I get more Nylon work I will need to develop a better solution than the cheap eBay dehydrator though.
Yup. FYI my vacuum setup was about A$200 for the 2 stage, 9cfm, 1hp pump and A$100 for the vacuum chamber kit.
OK. That's affordable and justifiable. Do you mind sending me links nowhere you got them from?
I initially got this Kit - https://www.ebay.com.au/itm/2-Gallon-Vacuum-Chamber-and-3CFM-1720RPM-1-4HP-transparent-cover-Pump-Degassing/222605 but the pump was not strong enough, and after discussion with the seller, we traded up to the 2 Stage / 1HP / 9CFM one. It's still a cheapo pump but it does the trick for the amount I use it. I currently don't see any Kits based on the 2 Stage pump but you could contact him (or any of the other heap of sellers selling these kits) about swapping to the much stronger 2 Stage Pump. The key is actually getting a pump that can pull down to say 10,000 microns / 29.88hg / 1010mbar at which point water is boiling at -17c (it will even work in CBR in the winter)! Full table here https://www.engineeringtoolbox.com/water-evacuation-pressure-temperature-d_1686.html . The single stage one I had only hit about 30,000 microns / 28.67gh / 971mbar = water boiling at 30c
Also I did some functional testing on filaments you might appreciate - https://forum.prusaprinters.org/forum/english-forum-awesome-prints-hall-of-fame/practical-filament-tests/#post-173183
Looks like I too have to dry the ePA-GF some more. Just did an anneal baking test with identical part in both ePA-GF and ePA-CF in an oven for 2hours @ 150c. I measured the before and after weight and this is what they lost.
- 0.5% = ePA-GF
- 0.1% = ePA-CF
My ePA-GF prints look better than my ePA-GF and they are dimensionally accurate. The ePA-GF is bigger by about 0.5mm all round so things like holes are too tight. I found this article - https://www.formfutura.com/blog/formfutura-news-1/post/styx-12-nylon-in-dept-guide-14 that suggested (with Nylon 12) you have to get it down towards only 1% to print well, and that is hard with something as hygroscopic as Nylon. They also warn of over baking the filament for too long (but don't state the issue). If I could drive 0.5% out of my ePA-GF test print it looks to still be too wet. I'll give it another round of drying on the weekend. (heat and vacuum). What I also found facinating with the article is that they then suggest once printed you want to then place your printed part in a water bath to absorb moisture which will increase it's strength! Moisture is only bad when printing.
The other thing to love about ePA-CF is it is 10% lighter than ePA-GF, so you get more filament for your $$$.
Thanks for all of that. I too like the ePA-CF but I wanted to try the GF because eSun's data say that it is stronger. Counter intuitive but my speculation is that it is because the glass fibres are actually long enough to contribute strength as well as dimensional stability. The Carbon Fibre in filaments is usually very finely chopped strands. I'd love to see some objective comparisons between the two. I also like the finish on the CF parts better too - important when you are keeping customers happy.
I'll read through your links whenI get a bit of time.