Reinforcing 3d Printed Parts With Fiberglass




Introduction: Reinforcing 3d Printed Parts With Fiberglass

About: Some people can work on one project at a time. Not me.

Have you ever been in a situation where you've 3D printed something, and when you took it off the build plate you realized that the item didn't have the structural integrity you had hoped for? I recently had this experience after a 48 hour print job, and in this tutorial, I'm going to show you how I transformed the 3D print from fragile junk to rock hard awesomeness.

The back story: A couple of years ago, I decided to craft a Star Wars Sith Acolyte Eradicator costume for myself out of foam, and I posted my instructions and progress here. Since that time, I decided to go with a costume that is more screen accurate and rigid. To help me along in my progress, I purchased my armor files online and proceeded to spend many hours printing the first piece. To my dismay, the chest piece I printed felt brittle and flimsy. For something that was going to sit on a table, this wouldn't be a problem, but this was something that I planned to wear as armor. Flimsy wasn't going to work.

As I considered different options, the one that intrigued me the most was fiberglass, and after a bit of research, I took the plunge. The end result was exactly what I was hoping for, and I'm going to show you how I did it.

Step 1: Gathering Supplies

First, I made a quick trip to Home Depot to pick up some supplies:

  • Fiberglass cloth (the kind I got was unstarched, and it worked great)
  • Fiberglass resin (the hardener is included in the snap-on lid of the container)
  • Plastic mixing containers
  • Throw-away brushes
  • Stir sticks
  • Gloves

Step 2: Preparing Fiberglass Cloth

Some people have mentioned that you need very sharp scissors to cut fiberglass cloth. Since I had a pair of sheet metal shears lying around, I decided to use them instead, and they worked great!

Turning the 3D printed piece over to the unfinished side, I placed the fiberglass cloth on the 3d printed piece and then cut the fiberglass to fit the piece. Once that was done, I removed the fiberglass cloth from the piece and traced it out on the rest of the fiberglass cloth.

Then I folded the fiberglass in half and cut out the traced outline through the two layers. Once that was done, I had three nearly-identical sheets of fiberglass cloth that were cut to fit the piece.

Step 3: Applying Resin and Fiberglass

Using the instructions on the fiberglass resin container, I put on my gloves and mixed a couple of ounces of resin along with the hardener using a stir stick, scraping the sides to make sure things were well mixed.

Then I used a throw-away paint brush to paint the back of the armor piece with resin. Once that was applied, I took a sheet of fiberglass cloth and carefully spread it across the resin. As soon as it was pressed down, I brushed on a second layer of resin on top of the fiberglass cloth. When I had completely covered the fiberglass cloth with resin, I put down another sheet of fiberglass cloth followed by more resin, another cloth, and the final coating of resin.

Step 4: That's More Like It!

After letting the resin harden for a couple of hours, I went back to the garage to check on things. The resin had hardened and was nicely bonded to the 3d printed piece.

While the piece still needs some cleanup, including filing and sanding off the remaining fiberglass, after few minutes work adding the fiberglass and a couple hours of waiting, my armor had been transformed from flimsy junk to a strong piece, exactly as I had hoped.

Have you already used this technique before and have tips or suggestions? I'd love to hear them. And if you use this technique, I'd love to hear about it in the comments!

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    7 Discussions


    2 years ago

    Oh, hello there)


    Question 2 years ago on Step 2

    I fell in love with the Sith Acolyte Eradicator as well...awesome costume. Are the 3d files available to purchase or to provide for aspiring acolytes?? *grin*


    Answer 2 years ago

    I used PLA. :)


    Question 2 years ago on Step 4

    Good idea but little question: what do you use (or suggest) AFTER, I mean over the resign/fiber, to smooth it ?


    Answer 2 years ago

    For my application, that wasn’t a problem. It was the back of the armor, so it won’t be seen. But if it’s going on a visible area, you’re just going to use a little more resin on the final layer and then sand it smooth once you’re done. It would certainly take some work, but if you’re careful when you apply the fiberglass layers, it should be totally doable.