Issue using fiberglass resin & cloth to reinforce armor

[RamenN00dl3]

So I am running a test to check a few things in using fiberglass cloth and resin to reinforce the inside of armor pieces I am working on, and found that when cured, the fiberglass seems to not adhere very well to the 3D print, so poorly that i was able to pull it off almost like a casting. Just curious if this is normal, or if there is some other step I need to take to make sure it adheres well? This started as an air pocket that formed after I flexed it a bit to test, and with some minor flexing and prying it popped off.

For reference, this test piece wasn't sanded at all, however I don't plan on sanding the inside faces of the armor that this was going to reinforce. The resin was cured properly with enough hardener as well. The armor will have some nooks and crannies that I think will give this more teeth, so maybe it's just the shape of the piece I tested, but I'm curious to see what others think and if there are any tips for working with fiberglass and resin to reinforce prints. Granted I coaxed this along a bit, but that's part of what I'm testing as well. I feel like with natural movement this could have happened over time, and what it tells me is it really wasn't doing much to reinforce, but maybe that's just my unfamiliarity with the technique and product.

 

[MrJamin]

Can you describe your process for applying the fiberglass + resin?

 

[RamenN00dl3]

Can you describe your process for applying the fiberglass + resin?

Not much to it, I mix the resin in the appropriate ratio, put a little down on the piece with a chip brush, add a piece of cloth, add a bit more resin to fully saturate it, do one more cloth piece, add a bit more resin and blot it all in and smooth it out as much as possible.

 

[Hein B287]

I think the inside of the print is to smooth. The resin has nowhere to grab onto. Maybe roughening it up with some sanding paper might help?

 

[MrJamin]

Not much to it, I mix the resin in the appropriate ratio, put a little down on the piece with a chip brush, add a piece of cloth, add a bit more resin to fully saturate it, do one more cloth piece, add a bit more resin and blot it all in and smooth it out as much as possible.

That seems like a pretty standard process.

I think that part of the problem with this test is just the shape of the piece. When applying it to something like a helmet or armor you will have much more complex geometry for the resin + fiberglass to grab on to.

You could always do a test with a different piece.

Here is a quick image of some of my fiberglass work (butt plate)

Even this simple piece has more spots for it to grab onto than your test.

 

[RamenN00dl3]

I think the inside of the print is to smooth. The resin has nowhere to grab onto. Maybe roughening it up with some sanding paper might help?

That could definitely be the case, I am going to sand the piece with 60-grit and try again this afternoon, see if it makes a difference.

That seems like a pretty standard process.

I think that part of the problem with this test is just the shape of the piece. When applying it to something like a helmet or armor you will have much more complex geometry for the resin + fiberglass to grab on to.

You could always do a test with a different piece.

Here is a quick image of some of my fiberglass work (butt plate)

Even this simple piece has more spots for it to grab onto than your test.

That could be for sure. I printed this test as a way to test for warping and heat resistance as I had tried a similar reinforcement process with Bondo before but it ended up melting half my pieces. I made this little curve piece so I could set it to cure in such an orientation that IF the heat were too much, it would flatten out. Luckily it seems to have held up pretty well, just faced with a different issue now. I agree that more complicated geometry will definitely help, though as above I think roughing up the surfaces a bit will help as well. Thanks for sharing!

 

[RamenN00dl3]

That seems like a pretty standard process.

I think that part of the problem with this test is just the shape of the piece. When applying it to something like a helmet or armor you will have much more complex geometry for the resin + fiberglass to grab on to.

You could always do a test with a different piece.

Here is a quick image of some of my fiberglass work (butt plate)

Even this simple piece has more spots for it to grab onto than your test.

Just curious, did you mask the edges prior to fiberglassing? What is the reasoning behind that?

 

[MrJamin]

Just curious, did you mask the edges prior to fiberglassing? What is the reasoning behind that?

I was doing it on a fully painted piece in the picture. I didn't want to accidently get resin on the parts that would be visible.

I also didn't have any issues with heat warping on any of the pieces that I did it for.