Trying to make a water tight part with PETG
I'm trying to make something that connects to a garden hose. I'm using PETG and I want this to be water tight. To figure out how to get the setting right, I took a model of a garden hose connector from Thingiverse and modified it to be a plug. That is, it just has a cap on top of a male end, so if you connect it to a garden hose, it should just stop the water completely.
I'm finding that it is not water tight. Water literally oozes out of it. I've done 3 tests, so far, and I have a 4th printing right now.
Test 1 had like four or five perimeters and a 25% hexagon infill. The second test, I set the number of perimeters to the maximum I could for the model. There are still some areas that it uses infill, but I set the infill to 100%. I also set the pattern to concentric, since my part is round. There are still some areas where the infill is rectilinear. I'm not sure why. Anyway, it didn't help. In fact, it seemed a little worse. Then I bumped the extrusion width up from .45 to .46 mm and I bumped the temperature up 5C. That also seemed to get worse, instead of better.
The print going on right now is at .47mm and 250˚C.
Oh, I am using the Prusa Edition of Slic3r, so I used the layer editing to add maximum detail for the layers where the threads are. I'm not a hundred percent sure of what that does, but the threads seem to come out smoother, so I'm guessing it changes the layer height from my default .2mm to something less.
I'm just going to keep adding extrusion width slowly, at this point. I'm going to leave the temperature at 250 because that is the max listed on the PETG roll.
Anyone have any experience with making parts that need to be water tight? Is there maybe a better material?
Re: Trying to make a water tight part with PETG
I may be misunderstanding the extrusion width setting. Should I be changing the extrusion multiplier, instead?
Re: Trying to make a water tight part with PETG
As a general rule, it's not possible to make truly water (or air) tight parts using an FDM printer.
The reason is that no matter what you do there's always going to be very small gaps between the layers.
If you need to make something water tight, you will need to coat the finished part with something to seal it. PETG is a problem in this regard because not much sticks to PETG.
You can try printing in ABS and painting the final part with a slurry of ABS dissolved in acetone. That has worked for me in the past.
You could also try flame-polishing the PETG part with a torch. I don't know if it will work or not but if you've already got a printed part to experiment with, why not.
Re: Trying to make a water tight part with PETG
I reset the extrusion width back to their defaults because making them wider made the problem worse. Instead, I bumped up the extrusion multiplier by 5%. That worked much better. I had about three or four tiny slow leaks. I'm going to try 10% and see what happens.
Re: Trying to make a water tight part with PETG
With an extrusion multiplier of 1.1, it is very nearly watertight. There was one tiny little leak at the seam, which I could fix with a bit of epoxy, but it was so small that it remained under pressure overnight. I think I will bump up the multiplier another percent or two, but it is probably as good as I need. The next challenge with be to make a water tight enclosure.
Re: Trying to make a water tight part with PETG
Try using more perimeters and use 100% print it worked for me.
Re: Trying to make a water tight part with PETG
I design vacuum chucks (to bond verify items using vacuum pressure) all the time. The material is porous (leaks air/any other fluid) so we melt the interior and exterior surface with acetone, don't think the threads would like this, so maybe just the exterior of the part and NOT the threads!
Re: Trying to make a water tight part with PETG
Just my 2 cents but...The only part that needs to be water tight is the end cap. The parts that are threaded usually aren't and if they are the water will ooze out past the threads anyway. You need a gasket. That will keep the water between the end cap and the inside of the hose. Water hose gaskets can be bought cheap at any hardware/ garden store. Or print your own with one of the softer filaments like TPU.
New project!
Hope that helps,
Neal
Edit...Just lay on the top or bottom (depends on your print orientation) layers until you're happy.