Prusament PETG UV resistance suggestions
Hi,
I'm relatively new to 3D printing, only done PLA and PETG so far.
Now, I need to print corner joints for an aluminum balcony fence. It's basically an L shaped piece that gets inserted into the 2 aluminum planks. On the corner there is a slightly larger cuboid that lines up with the planks. That is the only piece of plastic that is exposed to the weather. I can post a screenshot if it's any relevance. I also left a gap in the middle of the plastic, where I will insert a piece of L shaped metal for strength.
I was planning to print this with Prusament PETG Anthracite Gray. I was under the impression that PETG is UV resistant. But now I'm reading posts that it may not be so great. This will be very difficult to replace, so I need it to last for a very long time.
So is PETG good for this? I'm not that much worried about strength, e.g. planks getting separated, since I have a metal piece inside. I'm worried that the little corner cuboid could loose color or crack. How does PETG degradation usually manifest?
If it's not good enough does anyone have a suggestion on what to do? Some options:
a) paint it. What kind of primer and paint is the best for this application? I don't want the paint to discolor or crack. I've read that PETG is generally tricky to paint
b) use different material. I don't know which. I've looked at PA, but it's 3x more expensive than PETG, making it way too expensive for this application (I need 4-5kg)
c) would making the infill of the cuboid dense (or filling it with resin) help? If so, how much is enough? I was planning on 40% infill for the cuboid
d) the last resort is to glue pieces of aluminium over the plastic cuboid. What kind of glue would be best for this purpose?
Sorry for the long post. All suggestions are welcome
PETG is more resistant than PLA but you will see discolouration and surface deterioration in a few months. One unexpected result is that water can then get into the lay and frost damage may follow.
Paint - use a plastic primer first, is a great defence against UV and if well maintained may be all you need.
Gluing metal to plastic can be difficult as they have very different thermal expansion characteristics and many glues work-harden and fail.
A useful alternative filament is Bio-Pro by 3D Tomorrow, I have had small parts exposed for two years without significant deterioration but even that I would paint for added protection. It's almost as easy to print as PLA and only a little more expensive.
Part strength is in the perimeters, fill doesn't contribute much so 30% with extra perimeters should be OK.
Cheerio,
RE: Prusament PETG UV resistance suggestions
For something like this I'd use ASA. Unlike ABS, it's easy to print, UV resistant and has little (but some) odor when printed.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE:
Thank you for the replies. I have a few additional questions:
1. painting PETG. I doubt that I can only primer it, since I doubt I'll find a primer of exact same color. So, I would need to prime and paint it. The question is what to use? I have worked with a lot of spray can paints (quality ones like Montana and Belton), but I don't think it is a great solution. It is quality paint, but it doesn't last forever. After a longer time (few years) there is discoloring, and it may crack on smooth surfaces (e.g. aluminium, brass etc.). I don't know how it will behave on plastic, but I doubt it will last forever. It's an option, but one that most likely requires sanding and repainting every few years.
2. is there some transparent UV coating that I could paint it with, instead of primer and paint? Would that be a better solution? Maybe something like this acrylic varnish https://www.montanacolors.com/en/productos/mtn-pro-acrylic-varnish-spray/
3. as for Bio-Pro by 3D Tomorrow, it only comes in black and white, so I would definitely need to paint it. Since I need to paint either way, is there any advantage of using this vs painted PETG?
4. as for ASA, I haven't used it before, I was under the impression that it's difficult to print like ABS. Does ASA "last forever", or do I still need to prime and paint it? Also can someone recommend a quality brand for ASA? I've mostly used Prusament filaments so far, but I see they don't have anthracite ASA
RE: Prusament PETG UV resistance suggestions
5. Regarding infill/perimeter... I know infill doesn't add much strength, but it's not strength that I'm after. I just wondered would there be any advantage if the weather exposed part was more dense. Also, I don't see how will adding more perimeter help either. If PETG exhibits discolouration and surface deterioration, the top layer will deteriorate, no matter how many layers are there underneath. Currently I was planning on printing this with 3 lines of 0.6mm perimeter. I could add a 4th, but don't really see how will that help