Quote Originally Posted by curious aardvark View Post
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fred - whether or not a 3d printed part is water tight is largely down to the way it's printed.
So I'm learning. From what I've read, if I want stronger parts with better inter layer adhesion, I want to go to a larger nozzle. The supposed advantages are that the previously laid down layer retains more head, it will bond better as the new layer is laid down. It also speeds printing considerably. For aquarium parts I think I should actually consider the E3D volcano. As a start, I will get the largest nozzle my head supports.

For water tightness, is that all down to inter layer bonding?
Anything that isn't watertight can be painted with varnish, or any of the propriatary 3d print smoothing compounds around.
I don't think varnish will hold up long term in salt water. I'd have to talk to the smoothing compound manufacturers to see what might leach into water and how well those compounds hold up. It is definitely an option.

pet-g has much better layer bonding than abs, prints on an unenclosed machine and isn't much more expensive than abs. It also has a lot less shrinkage, which helps reduce micro gaps in the structure.
If I can print water tight from the get go, its almost 'holy grail' product for my application. If plain pet-g turns out to be too flexible, I can always go for a carbon fiber reinforced product.

Bonding would be the one issue. The only product available to bond to other plastics like PVC or acrylic it Weldon 40, a rather expensive two part bonding agent. If it works and this is the only down side, I can live with that.


The fumes from abs are not as much of the problem as it's shrinkage and all the acetone you end up breathing in.
Yes people use it, I suspect many of them do so beacuse they haven't bothered to look seriously at the alternatives. The materials advances in 3d printing filaments in the last few years is just astonishing.
Another material you might want to look at is ninjatek's Armadillo. It's a rigid supertough material, that apparently prints easily. Handling it you'd think you were holding some kind of hardened nylon. I believe they said it was polyurethane.
Pretty impressive stuff.
I haven't tried it yet - but had along talk to the ninjatek guys and handled a few prints. The only thing that impressed me more this year materials wise, was a fibreglass composite from an italian company (maybe spanish). That was as light and strong as traditional fibreglass and printed - again - on an unenclosed machine.

Then you have innofil's new Pro 1 - easily the best material I've printed with for ease of use.
Lots of different applications depending on how hot and how fast you print it. Also food contact safe.
Great info, thanks. I'm at the "you don't know what you don't know stage, so its hard for me to even know where to look for info on new plastics.

Edit: Regardless of the material I work with, I plan to enclose the machine. I've spent enough time around injection mold machines (very large ones) to understand how finicky plastic can be. Since I'm concerned with long term structural integrity, I want to manage the print environment as much as possible.