Gluing / sealing 3d-printed PLA

[Mark Robson]

Hi all,

Today I printed this rather nice piece on Bertha (the Hackspace 3d printer). It is a water distributor for the irrigation system I'm making, and the design came from Thingiverse here: http://www.thingiverse.com/thing:332937

I still have some finishing to do on this piece. The bottom surface, which was on the bed during printing, is obviously not water-tight (I think the edges mostly are ok). I plan to either seal it somehow, or glue a piece (laser-cut acrylic?) on the bottom.

Does anyone have any suggestions? I suppose if I screw it up, I'll ruin the piece, and it took 3 hours and a fair bit of material to make.

My obvious thought is either superglue, or hot-glue a piece of acrylic on the bottom. Would this work?

Mark

[Matthew Beddow]

The problem with supergluing parts like this is that they are quite porous and don’t make a very good seal as they don’t have perfectly flat edges.

Your best bet to water tight it would be to ‘tack’ it in place with superglue then use hot glue or silicon sealant (better) to make it watertight

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[Alex Gibson]

A couple of options: Definitely use Silicone sealant all over to help watertightness and it might fix the bottom if pressure is low, or if there will be some pressure, you could print a 1mm PLA disc of the same size with 100% infill, and using heat gun, ‘weld’ this to the bottom.  Or just go crazy with the hot glue all over the bottom, making sure the surface of the PLA is heated enough to melt a little and hopefully bond strongly with it.

 

You may find you have to re-print, specifying 100% infill to increase odds of it being water-tight.  But I know this involves another half day at rLab!

 

From: reading-...@googlegroups.com [mailto:reading-...@googlegroups.com] On Behalf Of Mark Robson
Sent: 23 June 2015 22:12
To: reading-...@googlegroups.com
Subject: [RDG-Hack] Gluing / sealing 3d-printed PLA

 

Hi all,

Mark

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[Matthew Daubney]

If you can figure out a way to apply it safely, a layer of epoxy would probably seal it up.

[Mark Robson]

If I laser-cut a disc of acrylic the right size, I can then hot-glue it to the bottom of the piece. If the glue doesn't stick well to the acrylic, it doesn't matter because the hot glue should seal the holes if I use enough, right?

Water pressure will be low (< 1.5m of head) and if it does leak a little, it doesn't matter.

Mark

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[Norro]

Its reasonable easy with fine printing to get it water tight without any modification. Slightly higher temp, generous extrusion.  However as I found with my shot glasses, alcohol doesn't have as good a surface tension and drips through! :P

Gluegun works well on pla though, I'd try that.

[Richard / rgproduct]

Superglue fails when wet.

Epoxy a good choice. strong, bonds to pla and not affected by water.

Having printed some boats, i found it pot luck if watertight, but high infill makes a difference.

I have dichlori here, that melts and welds pla so a good candidate too.

R

[Stuart Livings]

On 23/06/2015 23:52, Richard / rgproduct wrote:
> I have dichlori here, that melts and welds pla so a good candidate too.

That would be my best guess (no personal experience). Melting the
outside and/or inside layers using a chemical agent to fuse it into one
continuous piece of plastic.

[Tara Martel]

I would have printed it directly onto a piece of acrylic or olycarbonate having roughed it up first...

Obviously I have little experience of these things too.