Making waterproof PETG Prints

[Oliveros 11]

Hey Guys,

 

I'm trying to replicate a detergent system using 3D printed parts, I'm currently using PETG and after some tweaking it seems to be coming out okay.

Are there any tricks to making the prints waterproof, I find if I print 7 or 8, perhaps 3-5 of them come out good enough to consider they would hold water and slight pressure.

 

One end is a threaded connection, the other is a barbed fitting.

[DivingDuck 104]

Adding some extra walls and printing with slightly higher print temps can improve tightness. You need to play with these parameters a bit to find out a good compromise between surface and function.

[NBull 14]

Use one filament only if possible. if Pva is used be sure that it doesn't string or ooze. since this can be caught between the layers and make holes.

 

Go with a decent layer height 1.5

 

Print at relativly hot tempetures 

 

Extrusion Width can also help since it forces the layers to bond more eg. 0.48 on a 0.4 nozle 120% increase

 

 

Edited November 12, 2019 by NBull

[ultiarjan 1,223]

2 hours ago, NBull said:

Extrusion Width can also help since it forces the layers to bond more eg. 0.48 on a 0.4 nozle 120% increase

 

This seems counter productive to me, as the lines will also be printed 0.48 apart from each other. I would just keep 0.4 but increase flow % and temp a bit.

 

If you increase flow, and need working threads, you may need some  negative "horizontal expansion" (in CURA's  shell settings) to compensate

[NBull 14]

36 minutes ago, ultiarjan said:

This seems counter productive to me, as the lines will also be printed 0.48 apart from each other. I would just keep 0.4 but increase flow % and temp a bit.

 

Yes the lines will be 0.48 so the bond to lines on same layer wont be much difference. But for a 0.4 nozzle to make an 0.48 line it needs to squeeze out more material on the same spot to exceed the nozzles diameter and therefore bonding better to the layer beneath.

 

ps. don't know if Annealing the part will help make it more water tight or that's just work for strength!

Edited November 12, 2019 by NBull

[Oliveros 11]

Yeah, I made quite a few fittings yesterday and tested them, It's really hard to tell and they seem to break really easily, I mean, 1/4" is not a lot and it's tricky to try and compensate with wall thickness and making sure where the fitting joins the main parts body is strong, it's a bit of a learning curve for sure.

 

The fittings I made didn't hold up, the thread was fine, printed in 0.6 layer height and they matched the thread I wanted but it wasn't very strong and broke off If I tightened it too much.

 

Thanks for the tips though.

[geert_2 557]

What I would do: print slow and in thin layers, so that the molten material has plenty of time to flow, and to make a good bonding with the previous layer. But print at the lower edge of the temp-range, otherwise the material may decompose due to sitting too long in the nozzle. Make multiple walls, or make the walls so thick that the whole part consists of wall, instead of infill. Use a single nozzle, so you do not have PVA stings going throught the PET, leaving a hole after dissolving the support.

 

These models below are in PET. They are not hollow (except for the watermarks), but if they would, I am sure they would be watertight.

 

 

 

 

 

[Oliveros 11]

Interesting, good advice, thank you.