Fun With Carbon Fiber

[stumpy-ktm]

i just noticed twinshocker said not to use the pva ...... my finish is very smooth and nice .... i guess the trick would be to keep the pva layers thin, so they dont leave an undesirable surface . ....just use a damp cloth . no worries
cheers

[P B G]

nice work stumpy-ktm.

Always amazed how many people do not want a blingy leg. We're always covering them in foam and cosmetic skins which is terribly dull.

[P B G]

Originally Posted by therivermonster

Belt Sander: I needed something to trim up edges and flanges of the composite parts that we'll be making here pretty soon, and this seemed to be just the ticket. It is a Harbor Freight tool, so we'll see how it goes, but to be fair it has received some good reviews.
For anyone that is interested in looking into this sander, check out the YouTube videos about tuning the tool. I'll also include some details about how it's working for me when I have a chance to sand some stuff with it.

Get a dust collector ASAP if you're going to start grinding on composites.

[stumpy-ktm]

cheers pbg ... i cant stand the look of the foam covered pink leg ..... my real one is gone , i never want to try and look like the old leg .... i love this look and there are a couple of companies around the world who do sweet looking covers .... bespoke innovations in the states is one , and carbon stride in the uk is another ...

sorry to change the thread ..... start making stuff in carbon fibre .... i want to try kevlar next

[P B G]

Originally Posted by stumpy-ktm

start making stuff in carbon fibre .... i want to try kevlar next

I'll try to take some photos of how we laminate sockets, materials are all about the same,

Some S-Glass, some old school e-glass, I've seen some spectra layers added, but the straight carbon are interesting.

There is a machine being used by a few fabrication labs that weaves a braid directly to the positive model of the limb, so the braid is custom to the socket which is slick, no more stretching cloths to get them to conform, but we'll never own the machine - sad.

[therivermonster]

Originally Posted by stumpy-ktm

hello , keep up the good work , ... i have just made my first part with carbon fibre , i made a leg "fairing " for my prosthetic leg , ... one practise one in fibre glass , then i made the cf one , ... made a mold of my other leg to get dimensions right , them made a front and back mold ... high gloss finish for the surface , wax on the mold release , lay up the cf into the mold , wait till it goes off , then "pop" comes right out ... heres some pics .


the molds


fresh out of the molds

Stumpy, I just saw the pics. Very nice work! Is this your first CF project?

[therivermonster]

Originally Posted by stumpy-ktm

hey rivermonster ..... make sure your mold is as smooooooth as possible , wax on 5 or so coats of release wax ... then i use a wet cloth with the pva on it and wipe all over the mold to give it a nice barrier,,, let it dry then add another pva layer .... let it dry ...very important !!! then start adding either your gelcoat or resin and cloth ..... good luck .

That's kindof the work flow that I had in mind. I'm sure that the finish would look better if I could spray the PVA on, but that's not going to happen right now.
However I have been thinking about trying one of these.
BTW, Stumpy, what exactly do you mean by "use a wet rag" to appyl the PVA?

as for how i lost my beautiful leg ...go to "face plant" forum and look at "my story"
cheers

Good God, man! That is some story. The pictures of your x rays are crazy. I am very happy that you are still with us. It makes me happy that you are someone who really enjoys life. The photo of you in the wheel chair with the "I'm only in it for the parking" t shirt is priceless.

Check out Stumpy's story here.

[therivermonster]

Originally Posted by P B G

Get a dust collector ASAP if you're going to start grinding on composites.

I have a shop vac that I plan on using to suck up all the dust from the sander. I was thinking of making some sort of scoop woth foam board mounted to the sander. On the back of the scoop, I'll tape in a length of PVC and connect my vacuum hose to the PVC. I also ordered a resperator, so that plus some safety glases should do it, right?

[therivermonster]

Originally Posted by P B G

I'll try to take some photos of how we laminate sockets, materials are all about the same,

Some S-Glass, some old school e-glass, I've seen some spectra layers added, but the straight carbon are interesting.

There is a machine being used by a few fabrication labs that weaves a braid directly to the positive model of the limb, so the braid is custom to the socket which is slick, no more stretching cloths to get them to conform, but we'll never own the machine - sad.

I would love to see some pictures of how you guys fab your parts. Any video of the custom braiding machine in action, PBG?

[P B G]

Honestly, if its me, you get a HF coupon and buy a dust collector.

Shop VACs work OK, and as you mention if you confine the space so there is an airflow, you'll trap a lot of it.

But any fiber product, be it glass or carbon itches like crazy. At work we'll try to cover any sq inch of skin, wear respirators, goggles, but you'll still be itchy.

"all the dust" is a joke, if you are talking carbon and glass, you want to have as much dust recovery as is physically possible.

[P B G]

Originally Posted by therivermonster

I would love to see some pictures of how you guys fab your parts. Any video of the custom braiding machine in action, PBG?

I can try to find video - picture shows the basics of the machine... I really want one of these in house.





Cool bit of tech, as anyone who has done lay ups knows, getting the material to have the fiber orientation, thickness, and saturation you want can be tricky.

The process we utilize the positive plug gets destroyed on every part (rarely they are removed without destruction) Since the internal dimensions mirror loaded soft tissue, the rigid plaster plug usually just gets chiseled out with a pneumatic hammer leaving the laminated bit.

We laminate exclusively over PVA bags, which are preformed, we dampen them, stretch them over our models, and let them dry a bit with a heat gun, gets everything to lay smoothly.

[therivermonster]

I cut a swatch of the CF from the fabric that was delivered today. This is the first time that I have ever seen carbon fiber in the fabric form in person. It is really interesting stuff, especially the way it acts when you pull on it from the corners. I think that the fabric looks really nice. This is the discount 2x2 twill from US Composites.
Here's the little swatch I made.


Things have been a litte bit busy lately, but I did manage to make a bit of progress on the mini fairing plug. I think that the bondo work is done (I hope).



I picked up a rattle can of high fill primer, so I am hoping to just use the primer and some glazing putty to finish it up. One problem that I am having is the hot glue is coming through in some spots, and it just doesn't sand away. I'll have to figure out how to handle this issue. Let me know if you have any ideas.
Here the plug has been sprayed with one coat of high fill primer.



When I get all the supplies that UPS delivered today into the shop tomorrow, I'll try to take some pictures.
Now I need to figure out how to manage these rolls of cloth. Hmmm....

[stumpy-ktm]

monster , i apply the pva by using a damp clothe to wipe on the pve , i just pour some pva on the mold and then use the cloth to smear it all over ....keeping it thin ....

as for the socket weaving machine ..... holy shit !!!! the fit of that socket would be sweet ...my socket is carbon fibre as well layed up in the usual method ....hopefully very soon i will not have to use a socket ever again , i am looking into osseo-intergration .... ramming a titanium rod up my femur.... and leaving a bit sticking out so i can attach my knee directly back to my skeleton !!!! ...

oh and yes this is my first project ever with fibre glass and carbon fibre

[therivermonster]

Originally Posted by P B G

Honestly, if its me, you get a HF coupon and buy a dust collector.

Shop VACs work OK, and as you mention if you confine the space so there is an airflow, you'll trap a lot of it.

But any fiber product, be it glass or carbon itches like crazy. At work we'll try to cover any sq inch of skin, wear respirators, goggles, but you'll still be itchy.

"all the dust" is a joke, if you are talking carbon and glass, you want to have as much dust recovery as is physically possible.

I see that HF does have some dust collection options. Maybe as money allows I'll check these options out. Until then the Rigid vacuum will have to work.

[therivermonster]

Originally Posted by P B G

I can try to find video - picture shows the basics of the machine... I really want one of these in house.





Cool bit of tech, as anyone who has done lay ups knows, getting the material to have the fiber orientation, thickness, and saturation you want can be tricky.

The process we utilize the positive plug gets destroyed on every part (rarely they are removed without destruction) Since the internal dimensions mirror loaded soft tissue, the rigid plaster plug usually just gets chiseled out with a pneumatic hammer leaving the laminated bit.

We laminate exclusively over PVA bags, which are preformed, we dampen them, stretch them over our models, and let them dry a bit with a heat gun, gets everything to lay smoothly.

The weaving machine is crazy cool. Talk about getting a custom fit. Not to mention the fact that manufacturing must save a tone on materials due to very low waste. Very cool.

PVA bags, eh - very intersting. Kindof like those silicone vacuum bags that are fit to the part.