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direnc wrote: ↑

Thu Jan 07, 2021 11:47 am

fluidity wrote: ↑

Thu Jan 07, 2021 10:15 am

Cubic infill. It forms closed pockets. You can't print with big layer height though, the infil walls slope at about 45 degrees. Also, change your extrusion width from % to absolute, say you have a 0.4mm nozzle, set the extrusion path to 0.45mm. This will lay down wider tracks that seal better over the layer underneath.

I already used cubic infill, but that's probably not enough to make it waterproof. As for extrusion width, with a 0.4mm nozzle I sometimes go up to .6mm wide extrusions. Maybe it leaks at the seams. I do not remember what kind of seam placement I picked.

i have printed many joint for vacuum and they were always air proof.
i suggest you following:
- use Petg (for example pla is never air proof)
- use a bigger nozzle diameter it lets you thicker layers therefore less probability of having leakage (but you shall avoid to small printing angle)
- use a wider contour 3 4 time the nozzle diameter (for example nozzle 0.8mm 2.4 3.2mm contour). the perimeter being produced without interruptions should be always air proof.
- try higher printing temperature to let layer attach better each other
-modify design and avoi trailing edge be like a cusp.
assure that it finish like a segment or a fillet with thickness at least 3 4 time the nozzle
- to be air proof the infill does not play any role. the outer skin shall be waterproof. to definetly understand if the problem is the 3d print just print it again with an open infill and do a water leak test : put the wing underpressure under water and you will see bubble by leaking

now i read in thinginverse you have used PLA if it is true changing to PETG will solve 90% of the problem

direnc wrote: ↑

Thu Jan 07, 2021 11:47 am

fluidity wrote: ↑

Thu Jan 07, 2021 10:15 am

Cubic infill. It forms closed pockets. You can't print with big layer height though, the infil walls slope at about 45 degrees. Also, change your extrusion width from % to absolute, say you have a 0.4mm nozzle, set the extrusion path to 0.45mm. This will lay down wider tracks that seal better over the layer underneath.

I already used cubic infill, but that's probably not enough to make it waterproof. As for extrusion width, with a 0.4mm nozzle I sometimes go up to .6mm wide extrusions. Maybe it leaks at the seams. I do not remember what kind of seam placement I picked.

You shouldn't need to switch to PETg with it's associated humidity issues( very hydroscopic) to solve water intake.
It's about staying within the sweet spot of layer height vs over extrusion diameter. Big over extrusion only works if you crank the temperature up, have big layer height, very fluid plastic. PETg's surface tension is great for tidying up the fine details but the printing recomendations for it rely on aditional thermal mass of laying down thick tracks.

Check your noxxle diameter, if you have been printing wood, carbon or cleaned it with a bigger drillbit than 0.4mm then that will have compromised your print diameter vs nozzle diameter. My last print was like that. +20 % actual nozzle diameter and 1/3 nozzle diameter for layer height will seal well with cubic infill even on PLA. Also, big cubic infil pockets up the rick of unsealed pockets, smaller ones let the extrusion rate build to a better rythm closer to slicer settings with less inteferance from machine factors like bowden tube slack and over extrusion during fast moves.

Once you have it right for PLA you will have the advantage of less post cleanup due to the lower layer height.

petg is hygroscopic but it is not an issue: it is commonly used for water plastic bottle. i am using it for bindings and never had a failure in 3 year of application. up to you wich material are you able to print better

fluidity wrote: ↑

Thu Jan 07, 2021 6:33 pm

direnc wrote: ↑

Thu Jan 07, 2021 11:47 am

fluidity wrote: ↑

Thu Jan 07, 2021 10:15 am

Cubic infill. It forms closed pockets. You can't print with big layer height though, the infil walls slope at about 45 degrees. Also, change your extrusion width from % to absolute, say you have a 0.4mm nozzle, set the extrusion path to 0.45mm. This will lay down wider tracks that seal better over the layer underneath.

I already used cubic infill, but that's probably not enough to make it waterproof. As for extrusion width, with a 0.4mm nozzle I sometimes go up to .6mm wide extrusions. Maybe it leaks at the seams. I do not remember what kind of seam placement I picked.

You shouldn't need to switch to PETg with it's associated humidity issues( very hydroscopic) to solve water intake.
It's about staying within the sweet spot of layer height vs over extrusion diameter. Big over extrusion only works if you crank the temperature up, have big layer height, very fluid plastic. PETg's surface tension is great for tidying up the fine details but the printing recomendations for it rely on aditional thermal mass of laying down thick tracks.

Check your noxxle diameter, if you have been printing wood, carbon or cleaned it with a bigger drillbit than 0.4mm then that will have compromised your print diameter vs nozzle diameter. My last print was like that. +20 % actual nozzle diameter and 1/3 nozzle diameter for layer height will seal well with cubic infill even on PLA. Also, big cubic infil pockets up the rick of unsealed pockets, smaller ones let the extrusion rate build to a better rythm closer to slicer settings with less inteferance from machine factors like bowden tube slack and over extrusion during fast moves.

Once you have it right for PLA you will have the advantage of less post cleanup due to the lower layer height.

I just finished to coat my wing with glass but I printed the wing in 38 pieces with a resin printer. Will test and report back

Hi,
I would not get distracted by filament and infill discussions in the first step.
A laminate should be tight and with the effort you have spent I also would expect that it is.
In windsurfing times there was a rumor that exposed carbon fibers start do by capilar forces . But I think that is quite akademic.

I would suggest that you expose your wing to heat (sun or 50C in the oven). Cover it with a mix of water an washing detergent and you should recieve bubbles where the heated air of water starts to get out (and in in teh first step). You also can put it under warm water.

What I experiences durifng my countless tinkering failures is that pin holes oft remain pin holes after normal coating. I do not exactly why but I think that it has to do with the cohession of the resin or paint. Propper fine sanding and spackeling works best. And always bubble testing before the first maiden voyage. Just learned that last summer once again.

Your aproach of hand laminateing and the vacuum laminating is good. I had that in my mind to.
I guess spackling then is not a bad idea.
I had this problem always using corecork or even PVC with holes in to prevent air trapped underneath. The vakuum sucks out air from the core into bleeder layer. It only needs a wiff and you have pin hole. I read that 0,2 µm diameter is enough to enable kapilar water. The more air you have inside and the higher the temp differences on land and water are the more it will suck.

Here the Filament and infill discussion start to make sence.I guess you then start to make a bubble test with each single print part befor assemply and fix the holes with one second glue.

Dirk

Hi
Did you find anything?
Dirk