Bonding fiberglass to ABS 3d prints

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maker_dad

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Hi All,

I've been designing and 3d printing low-power model rockets from ABS plastic for a while now. I really like this approach because I can print the fins and body tube as one single structure. Everything comes out nicely aligned, and generally I only need to lightly reinforce the frame.

Recently I've been wanting to print larger models that can accommodate E and F engines. I figure that I'll need to reinforce the structure with something substantial, such as a few layers of fiberglass. (Otherwise the printed ABS layers will delaminate). In my limited experience, epoxy doesn't bond to ABS as well as to fiberglass or wood. So, this got me thinking....

If I brush a thin layer of acetone onto my 3d-printed parts, the solvent will melt the top layer. Then if I push a layer of fiberglass onto the melted top layer, the plastic will partially impregnate the glass. This hybrid abs-glass layer might be a better substrate for bonding subsequent layers of glass. Has anyone ever tried this with any success?

I've got a gallon of West-system from my days working in a boat house, and so I'd probably be using that with some 3 oz or 6 oz e-glass.

Thanks so much.

~Paolo
 

tfish

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John Coker did a video on testing glassing 3D parts...

[video=youtube;g7cVa0K_txM]https://www.youtube.com/watch?v=g7cVa0K_txM[/video]

I think it was IREC last year that I saw one group had printed up some fin 'cores' and then laid-up 2-3 layers of carbon fiber over those cores. I'm not sure what material they used but the cores did not like the very hot temps out at the launch site.

Bryce Chanes had some 3D printed fins go to mach 2 IIRC

Tony
 
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maker_dad

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Thanks!

Acetone would likely be too damaging if you wiped it down with it. This also has organic solvents, so don't spray too wet. Mist it on several coats.
Regarding acetone, are you thinking it would damage the ABS or the glass? Or perhaps just not promote good bonding? I use it all the time on ABS parts to clean up bad prints / glue parts together. (You can even make basic plastic glue by melting scrap plastic in a small jar of acetone).
 

dhbarr

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I have some ABS, acetone gassed, sanded, .75 oz fiberglass applied. Just regular epoxy, no adhesion trouble.
 

rharshberger

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Spray with this:

https://www.amazon.com/dp/B0007UAXJQ/?tag=skimlinks_replacement-20

Lets me epoxy to waxy paper. Also lets me prime and paint plastic nosecones.

Acetone would likely be too damaging if you wiped it down with it. This also has organic solvents, so don't spray too wet. Mist it on several coats.
I think the main reason the product is assisting with your bonding is because its 98.48% Solvents and Propellants, the Solvents are MEK (52%), Acetone (19%), Xylene (3.64%), and Ethylbenzene (.64%), the remaining percentages are Propane (11.73%) and Butane (11.27%), the remainder is probably lacquer solids. Probably just wiping the exterior of sono-tube with MEK would do the same job for less expense on the paper, the nosecones is where the lacquer solids and the aggressive solvents work together to adhere to the plastic.

View attachment Duplicolor Adhesion Promoter.pdf
 
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maker_dad

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Thanks for input, everyone. I ended up going with a (very) light coating of acetone to the abs. I found that while the plastic is still wet, I can push the glass into the abs just a little bit. When the solvent evaporates, the fiberglass is then bonded quite strongly to the plastic, enough so that I break the part by trying to separate the fabric. I had to let the abs / glass + acetone dry in a jig so that plastic didn't warp. After that, a layer of west system + one more layer of glass makes what appears to be a super strong part. I've attached a few pics of the (mostly) completed rocket. One shows a large portion of glass bonded to abs without epoxy. Still needs a bit more sanding and a little work to fix a few blemishes. The patchiness in the full resolution picture is just the underlying 3d printed structure. It's not solid so as to reduce weight and allow for through-structure bonding to the motor mount and other parts.


IMG_1727.jpgIMG_1751.jpg
 

dhbarr

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Hrmm, since FG/CF are so porous, I'm thinking lay the fabric, brush on acetone, clamp.
 

cbrarick

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I wonder how the weight and cost of the fiberglass reinforced ABS compares to thin-wall fiberglass so readily available now.
All the same, it's cool you can make these things from raw materials....
 

maker_dad

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Hrmm, since FG/CF are so porous, I'm thinking lay the fabric, brush on acetone, clamp.
You can also do it that way (lay glass, then acetone), but I'd be hesitant to clamp with anything heavy unless it provides pressure evenly on both sides of the part. The ABS I'm using is pretty then, only 0.8mm, so the acetone will weaken it greatly until diffusing out of the part.
 

maker_dad

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I wonder how the weight and cost of the fiberglass reinforced ABS compares to thin-wall fiberglass so readily available now.
All the same, it's cool you can make these things from raw materials....
Good question; I should have checked the weight of everything more carefully as I was building. Minus the motor mount, baffle, nosecone, and recovery stuff, the frame probably weights on the order of 250 to 300 grams. The tube is 80 cm in length. Overall the thing is a bit heavy for a 3 foot rocket, but it's also got too much resin. Black ABS infused into FG makes it a little harder to tell when the glass is wetted out.
 

JohnCoker

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Thanks Tony for the link.

I would be wary of treating 3D printed parts with solvents. That would be likely to make a smooth surface, which would provide a poor bond. In fact, I improved the bond to the PLA part by sanding it.
 

OverTheTop

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I tried bonding an iso-grid core (3D printed in ABS) so some CF sheet. ABS surface was flame-treated and then bonded to the ABS with West Systems 105/206. Extremely variable results. Some parts stuck well, others easily peeled. Changed the core back to G10 F/G for the final parts instead.

notbonded.JPG

The bonding seemed very process-dependent which is why I went back to something more predictable.
 
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