3 Attachment(s)
Is ASA much easier to print than people think ?
Hi All,New to the forum but have been 3D Printing about 9 months. In that time I've printed mostly in PLA but have also used PETG, TPU and now ASA.PLA of course is very easy to print and get good results from but has limitations with temperature and UV resistance.The next material up for temperature resistance is PETG, however I have really not had a lot of luck with PETG and just don't like the way it prints, with oozing and stringing being the main issue. I've tried all the usual tuning techniques with temperature, retraction, (I have a direct extruder) fan speed, etc but cannot fully tune out stringing, with even print jobs that are mostly solid blocks having fur on them and complex shapes having an unacceptable amount of stringing. I've also noticed inexplicable inconsistencies in layer bonding strength from one print to another where sometimes prints come out more brittle than other times.To test and tune bed adhesion and layer bonding strength I have a small model I designed with a flat octagon base and two small towers with bridges which can be downloaded here:https://www.printables.com/model/571...r-test-printIt prints in about 10-15 minutes and only uses about 4g of filament. With PLA you can easily get near perfect bridging and zero stringing, with PETG I always get significant stringing no matter what, and that is with a brand new roll of filament which has just come out of the sealed bag. (And when not in use I put it back in a sealed bag with desiccant) To test layer adhesion the whole base can be bent - PETG will sometimes "crackle" when doing this due to internal layers not being bonded properly, and if you bend it far enough it sometimes shatters. Snapping off the towers also gives a good indication of layer strength, with PETG usually being very brittle in this test compared to PLA, and also inconsistent when making small changes to printing parameters. (For example sometimes increasing hot end temperature makes it more brittle not less!)In short my venture into PETG is a frustrating disappointment and I only use it where absolutely necessary for temperature resistance on a part where I know the shape will allow me to clean up the stringing afterwards.Wanting to print some parts that will be subject to high temperatures (things like plastic clips for use in cars) but not liking how PETG strings so much and often comes out brittle I started thinking about ABS or ASA - however I don't have an enclosure, and most articles say these can't be printed without one, although I have seen some people say that ASA is a bit more lenient than ABS and has less tendency to crack and warp. It is also UV resistant while ABS is not so I thought why not do some experimentation with ASA ?I also want to experiment with Cura's "draft shield" feature to see whether it could make an ASA print work on an open printer that might otherwise suffer with cracking and warping.So I ordered a roll of black ASA and started doing some experiments a few days ago and I am blown away by how good it is and what I can get away with without an enclosure! :)Yes, it has some peculiar properties compared to either PLA or PETG when printing and needs very different settings but within a day I had worked out what works well. I print directly onto a powder coated spring steel PEI sheet.A few things I've learnt so far:1) Plus - It does not string, at all, even at very high hot end temperatures. This is incredibly welcome after the stringy mess that is PETG. The roll I have says 210-250C is recommended, which is a bit lower than what I've seen recommended online, however after tuning I've settled on 250C and I just get NO stringing at all with my other settings. I have printed two tall cylinders at once causing lots of transit moves between them during the print - usually with PETG this would cause massive stringing between the two towers but here there is none and they look flawless as if I had printed them one at a time. I would say it is less prone to stringing than PLA despite the much higher printing temperature. Incredible.2) Plus - Bed adhesion to a powder coated PEI bed is very good, but only if the bed is very hot. My bed can only go to 100C and I would say that any less is insufficient. One of my standard quick test prints is a simple bar that is 10mm wide, 5mm thick and 100mm long. Despite the spool recommending 60-100C, printed with the bed at 90C the end starts to lift up and warp before the print is even finished due to poor adhesion, however at 100C it sticks firmly without even needing a brim, in fact I have printed stuff like a 100mm tall 20mm diameter cylinder standing on end with no brim or other bed adhesion aids and it sticks like glue at 100C and takes quite a bit of force to dislodge after printing if you try while it is still hot but lets go by itself if you let the bed cool first, very much like PLA on this bed. So I always use the full 100C bed temperature for ASA and so far I have not had any bed adhesion issues or warping away from the bed.3) Minus - even a small amount of part cooling fan (10%) can cause a rough surface finish on the top layer at the ends of a part. This is particularly noticeable on the bar I mentioned earlier. I was initially printing at 240C with 10% part cooling fan and the roughness at the ends was quite bad. I then increased the temperature to 250C which reduce the area of the rough patch but didn't completely eliminate it. I realised that the ends were affected worse as the part cooling fan would linger over the ends more than the middle so I tried 250C with no part cooling fan at all and that eliminated the roughness completely and gave a surface finish comparable to PLA. This can be seen in the attached photo of the three bars where the left part is 240C with 10% fan, the middle is 250C with 10% fan and the right is 250C with no fan.4) Plus - Bridging is incredible - as long as the layer time is sufficient you can get almost perfect bridging with no part cooling fan, which genuinely surprised me. This can be seen with the second photo. The tower on the left is 250C with no part cooling fan - the bridging is iffy and the towers are also very blobby - while printing it was clear that the layer time was so short that the next layer was going down while the previous one was still soft as the towers were wobbling during the print. In the middle one I turned the part cooling fan on to 10% for the top half and you can see the towers became a lot cleaner and the top bridge is better, however it did add a small amount of stringing and as previously seen this would cause a rough surface finish on a top surface. The right hand one is no part cooling fan but I enabled a draft shield. While there was no draft to shield the time spent printing it increased the layer time of the towers dramatically giving enough time for natural cooling without fan and the result is basically flawless and is good as the best I can get from PLA with part cooling. Because the material doesn't suffer from stringing there is no stringing between the part and the draft shield as there would be with PETG.5) Minus - can't print quite as fast as PLA, but faster than PETG. I print on a Sovol SV06 Plus and I can print most PLA prints at up to 150mm/s, which I would consider to be draft quality, although for a more delicate/intricate print I often drop to 80mm/s. With ASA I'm finding I can print at 150mm/sec from an extrusion point of view however if the print head is seeking between two parts (such as a part and a draft shield) I'm seeing some artefacts on the surface of the part where the seeks come and go from the part - sort of bumps. These seem to be periodic bumps spaced up the print and I believe they are caused by mechanical resonances in the printer itself when operating at that speed. Dropping to 80mm/s seems to eliminate these artefacts and give a blemish free surface even when seeking to and from another part or a draft shield. All the prints shown in pictures were printed at 80mm/s.6) Minus - printing in ASA does small a little bit, nothing bad but if you are near the printer you can smell it. Must be printed with ventilation like a window open which could be problematic for drafts in the winter, although printing a draft shield may help with that. (I guess I'll find out when winter comes..)7) Plus - So far I have not experienced any cracking or warping on taller items as I had been expecting from ABS/ASA on an open bed printer, and this is a genuine surprise after watching countless videos showing how much cracking and warping is an issue with ABS/ASA without an enclosure. I have been deliberately trying to print things that should fail with cracking or warping so that I can reprint them with a draft shield to see if it helps, but so far nothing has cracked or warped so I have not been able to validate the draft shield except as a means of increasing layer time to improve bridging!Among the things I have tried are printing various tall cylinders - I've tried both solid (with relatively dense infill) and also thin walled cylinders with and without a draft shield and none of them have failed and they all have almost impeccable finish and feel quite strong with good layer bonding. See the final picture for some examples of these.In short, I'm really impressed with ASA and it will be replacing PETG for me for most things that PLA can't do as it has higher temperature resistance, prints without stringing, seems to have much better layer bonding than PETG and almost as good as PLA, has good bridging and seems to give a lot more consistent results. Perhaps you would have problems with some really large dense prints without an enclosure, I guess I'll find out, but without and enclosure I'm still able to print useful sized functional prints with relative ease and they are coming out really nice often on the first try.A summary of my settings:Hotend 250C, bed 100C, part cooling fan 0-10%, 80mm/s maximum print speed, print a draft shield to use up layer time if small details like towers/bridges are suffering due to short layer times. Try not to use any part cooling fan if you want the best surface finish.Anyone else have good experiences with ASA on open bed printers ?
