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...