Friday, December 02, 2016


It's been a long time since I posted here.  I'm still building carbon frames but making a big change in direction.  Below is one of many steps towards molding tubes and frame components in-house.

3D Printing:

In order to create molded carbon tubes and frame parts I needed to be able to mold silicone bladders that fit the inside shape of the final carbon parts.  I didn't want to use wrinkle prone sleeves or other methods.  I want to use shaped bladders.  In order to make molds I purchased a 3D printer.  I chose an Atom 2.0 Printer for the accuracy and print volume (particularly print height).  Now, each iteration of a mold costs about $10 worth of ABS filament.

Here are mold components for a bottom bracket bladder being printed.

I lightly sanded the parts, smoothed them with acetone and covered them in mold release.

I mixed up the two part silicone and attempted to degas it prior to injecting into the mold.

I used an empty caulking tube and caulking gun to inject the silicone into the mold.  It started to pop open (the end cap) so I had to clamp it shut during the injection phase.  Having made the mold parts out of "clear" ABS I could tell the mold was filling well.

After letting it cure overnight I trimmed the excess silicone and opened the mold.

It was a bit of a struggle to get the core part of the mold out of the bladder.  Luckily the silicone stretches a long way.  The finished bladder has some flash and a few bubbles in it but it holds air which is the important part.  The flash trimmed of easily leaving a smooth outer surface.

I've also been using the printer to make models of each tube I intend to mold. More to come...


toddsters said...

Very interesting work. Any more progress? Can you show how you molded the bottom bracket?

Junyoung Choi said...

Hello. I read all your posts. It's very intersting and very educational for me. I also make custom carbon frame in Seoul South Korea.
I'd like to ask you how to make 3d printed mold to carbon fiber parts with silcone in detail.
Would you please teach me? I hope you to become my Artisan teacher. Here is my contact. instagram tonychoi0608. Please Please Please I want to learn how to build carbon frame like you.
Thank you.

Best Regards.
Tony Choi.

aaron said...

Nice work. Like the idea of making the internal silicone molds.