First Composite/Mold Adventure

General Composites Discussions Showcase
#1

Well, I’m brand new to composites and just got my first orders of 12k tow, mold making supplies, epoxy, a few yards of texalium, a few yards of fiberglass, and a bunch of other stuff. I thought I’d share my first projects and get some feedback to help me out in the future.

First, I decided while taking down an old light fixture that it had a really cool shape for a decorative bowl. I decided this would be my first mold. I set it on hardboard with clay around the outside and covered the hole in the middle. I left a little gap between the clay and glass, not enough to let gelcoat through, but enough to make an indented line in the mold so I know where to cut the edges of the bowl when it comes out. I waxed the part and the board about 5 times and applied a layer of PVA. I put a layer of gelcoat on the glass and realized it probably wasn’t going to be enough after it sat for a while and I could still see clay through it. I waited about a day and then filled my gaps with another coat and extended the flange a bit. I let that get mostly cure and just used bondo on the back of the mold since I had that laying around and this isn’t necessarily a mold that will be heavily used, just more a learning exercise. I’ve got to say I’m very pleased with the practically mirror finish of the mold. The glass pretty much slid out of the mold and left a really good result. I’m not impressed with the one rough spot in the mold where the circle of clay is in the middle. That doesn’t concern me since that will be the bottom of the bowl. I’ll figure out how to prevent that from happening in the future when it does become important. The mold still needs to be cleaned up and trimmed down.

Since I got a couple rolls of tow (12k and 24k) with the intent to make some small stuff and at some point furniture, I decided to try laying it up as a picture frame as my first project. I traced the dimensions on the back of a sheet of glass as a template and then I applied PVA on the other side. I cut several pieces of tow to size and put them on a piece of wax paper. I decided to wet the tow out on the wax paper based on what I read about working with tow. I just laid the pieces onto the glass overlapping the different sides so they would really stick. I noticed that the tow got pretty wavy as I was laying it on the glass. I let it cure completely and took it off the sheet to see a paper thin, somewhat flexible shape. I’ve since sanded it down and I’m going to apply a few more layers to build up thickness and make it more rigid. I’ll trim it down with a dremel to the picture frame dimensions that it should be. I figure at that point I’ll wrap tow around the frame just to give it an interesting design. I’ve decided not to wet that out first and rather coat the frame and just wrap the tow tightly around it. After that I will coat the tow with a layer of epoxy on top and I won’t have to worry about distorting it. Looking back, I probably should have sandwiched it like a flat panel between sheets, but I didn’t think of that at the time.

#2

Thank you for that new idea of a picture frame!!! I would hide layers of fabric between the carbon tows, just to give it all around strength.

#3

That’s a good idea, but the thing is still surprisingly strong for just 3 layers of tow. If I make another I’ll do that for strength and uniformity of the layers. I still have to cut it down to the size I wanted, but it’s pretty much finished. I’ll have to rig up something to hold the glass against the frame tonight. I’m thinking that can be done with just a few pieces of tow and clay that I can remove when it cures. I’ll post more pictures of how it comes out.

#4

In the first picture I laid a second set of 12k tow down on top of the first layer. For the third layer I decided not to wrap the frame, but rather just lay another layer on top, but use 12k. I went around the frame laying each tow on top of the previous and worked my way toward the center. I applied a thin layer of resin to stick the fibers in place and then another thin layer on top just to make sure they were stuck. It seems like the roll of 24k tow possibly has something to bind the fibers into a flat ribbon and it stays that way even when I wet it out. The 12k doesn’t and it just frays like crazy and gets all wavy. If I would have just used 24k, I’m pretty positive this would have come out much straighter and not so wavy. Anyways, after the top layer cured, I sanded the resin completely off the top exposing the carbon. I applied about 4 layers of a really cheap clearcoat. After that dried I just used the back of picture frame that I had and laid it where I wanted it. The back had little tabs that turn around to hold the back in place. I laid two strips of tow that was wet with resin on top of the tabs. After it dried I pushed the tabs down to break them loose. The result is a fully carbon fiber frame besides the glass and back. I may take some pictures of the back of it.

It looks horribly crooked in the pictures, but it looks really good in person because the flaws aren’t as obvious at all. The shine and color variation is awesome. I think I may try to make another that is a bit straighter and finished a bit better. The fact that it is wavy seems to add character and interest instead of making it look crappy. If I wanted to make it look much more uniform, I would use a mold.

#5

i think the decorative bowl with the weave pattern your using with the tow would look SICK…

#6

Hi all from tishGirl

#7

or a mix between carbon and kevlar tows in the layup…like a yellow and black caution tape!