How to vacuum seal a 3d printed nozzle adaptor for SMT PnP

For SMT PnP a small adaptor has been made around a simple syring needle and a force sensing resistor FSR 402. The stack of nozzle holder, FSR holder and top item with the vacuum pipe is made with PLA (0.25mm layer thickness, 0.5mm nozzle, 4mm wall thickness with 4x solid at the borders, 195 degC filament temp.). The upper and the lower parts are mounted by screws to the middle part with the FSR. It has about 4800mm2 surface at the outside (40mm diameter, 40mm height).

Unfortunately the 3D printed parts are not vacuum tight right after the print. I can breath through the hose mounted to the adaptor ... it means most of the vacuum is left until it comes to the nozzle tip. At the moment liquid rubber on the inside and paint on the outside seales it enough. But it takes time (2x 24h) to get it dried :-(
The printer runs with slight underextrusion to fit inner and outer design geometries (0.5mm nozzle gives a 0.58mm string).

How can I get the parts really airtight without a long-standing postprocessing as described above?

Edited 6 time(s). Last edit at 08/26/2015 02:48AM by lutz_dd.

... infiltrate it with acrylate ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Could you please be a little bit more specific with the term "acrylate". My first thinking was "Sekundenkleber/cyanacrylate" ... the 2nd idea "Akryllack". I'm not sure what you are pointing at?

... my first idea was "Sekundenkleber" for its lower viscosity, so better infiltrating properties ... but "Acrylfarbe" could be usefull too ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Thx ... will check "Acriylfarbe". Need to print a 2nd one anyway for the smaller 0603 parts.

Made a new one over the weekend. Let the parts swim for about 1 hour in the thinned paint (mixture receipe is 50:50/water:paint). It is hard to tell wether the thinner paint is a good idea or a flaw. The PLA was not cleaned before (e.g. grease) and it behaves to some degree reluctant to get the surface wetted.
But the result is good ... all the air goes through the nozzle. The proposal was a good idea .... thank you Viktor.
Btw. even the print failure in the thin section seems to be sealed.

Edited 1 time(s). Last edit at 08/31/2015 12:11PM by lutz_dd.