Any chemistry types know if PET based prints (like T-Glass,

3D Printing
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1

Any chemistry types know if PET based prints (like T-Glass, or CX-Glass) can be smoothed, as is done with ABS and acetone vapor procedures?

Anyone have experience making water-tight prints (at insignificant pressures) with ABS and vapor treatments?

I’m embarking on quite a lot of R&D with such techniques, and thought I’d see what experience the community might have…

Thanks!

2

If your ABS prints don’t come out water-tight, you’re likely under-extruding or printing way too cold. Vapor smoothing can take them the extra step of becoming air-tight, but water-tight is definitely achievable without post-treatment.

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I haven’t heard of anything that dissolves PET the way acetone dissolves ABS. The best I’ve been able to come up with for smoothing non-ABS prints is to paint them with a liquid made by dissolving ABS in acetone. It fills the gaps as a liquid, then the acetone evaporates leaving the ABS in place, making the prints significantly stronger and somewhat smoother.

4

I don’t believe there’s a suitable solvent for PET. I’m currently playing with ABS perimeters and tglase or nylon infill. Early stages right now but if I can get things to bond nicely, it’ll give parts with tglase strength and ABS surface finish.

5

That’s awesome @Tim_Rastall , I’ve been following your kraken work closely, and plan to put one on a rostock max in the coming months.
@Thomas_Sanladerer , I should have been more clear. I’m printing parts that will be underwater, and need to keep water out (like specialized caps for PVC pipe.) I’m not at any depths greater than 3 or 4 feet (~2 psi gauge pressure), and haven’ t actually done significant testing yet (so they may be water tight) - but was looking for anyone’s experience or troubles making cups or other water interfacing parts.
@Laird_Popkin - clever idea! I’ll give it a try if it proves necessary.

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Ah, if you need water-tightness that’s different from smoothing. I’ve been printing T-glase with very thick layers (0.4mm), and it’s amazingly solid. I wouldn’t be surprised if even one shell was watertight, though it wouldn’t be terribly smooth. :slight_smile: I’ve found that thicker layers are much more watertight than a finer resolution, because there are fewer, fatter layers bonding. And while it probably doesn’t matter for your application, the layers are much more clear, so they look quite nice.

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Polyethylene, pe, is pretty solvent resistant, but AFAIK, pet gets a bit softened by gasoline and kerosene, at least that’s what I’ve been told by people discouraging me from storing either in milk jugs

8

Back in the days of the Sells Mendel, one would print a shot glass as the very first thing on a new printer. Usually, it would take a couple of tries to get it leak-free, but you’d eventually get there.
Back then, I did manage to make a shot glass that didn’t look pretty at all, but did the job - nowadays, all my prints come out watertight, at least when there’s no pressure involved. I wouldn’t trust them under a whole meter of water, tough, since at that depth the pressure easily overcomes the surface tension that might give the illusion of water-tightness. If your parts don’t need to 100% dimensionsally accurate, brush on some ABS goop and they’ll definitely be pressure-proof.

A quick Google run for PET solvent brought up this short Yahoo thread, which mentions several possible solvents for PET: http://answers.yahoo.com/question/index?qid=20100918070247AAwAWnM

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So, nylon would be the other option eh? The molecular bonding of hot nylon ensures a very strong bond and thus (I assume) watertightness. Or would nylon be too flexible for your application?

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Nylon should work for the kind of parts I’m working on, put in an order last week! Didn’t think of the chemical nature of the bonds, and don’t look forward to wrestling with Garolite and it…

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PVC glue does wonders for getting any print water-tight. But it’s a bit thick for proper smoothing.