Fun With Carbon Fiber

[therivermonster]

Originally Posted by djborden

Be very careful about cutting, sanding or grinding carbon fiber. I have been told it is VERY bad for you to inhale it. Not unlike asbestos. Just be sure to use an appropriate mask and dust control.

David

That is a very good point, David. I do wear a respirator when grinding on this stuff.

[DaBit]

Hmm,

I do get that orange peel texture also sometimes.



Out of 12 panels it was this bad on 1 panel and not quite as bad but visible on 2 more. The others were OK.

The 'moon surface' panel epoxy surface was cleaned with tap water, sanded with 80-grit, rinsed with deionized water and then dried with a hair dryer before applying the (tinted) epoxy. Outside temperatures were close to 30C / 85F, so no additional heat was used for curing and the panel was laid flat inside to cure. Epoxy mixed by weight and mixing ratio was spot on. No finger prints or other greasy contaminations either; I wear nitrile gloves all the time. No wax or other mold release agents were used either.

I am currently using a very fluid/low viscosity (think 'warm olive oil') epoxy system with a very long pot life (200 minutes) which also needs a post-cure for maximum strength and heat resistance. Since it is so fluid it is hard to even get bubbles in it. This does seem to worsen the orange peel compared to regular epoxies with 30-40 minutes of pot life and higher viscosity.

Strange thing: once this happens to a surface, it is almost impossible to get subsequent layers of epoxy to flow nicely. I tried wiping with acetone, rinsing with brake cleaner, wet sanding, etcetera.

For small parts it works to just clean/sand it and fill the craters with a quick-setting epoxy glue. For larger parts this is an expensive option; epoxy glue bought from the hardware store is over 16 times more expensive than epoxy resin bought in 'volume'.

I am going to try the sprayer-with-acetone method next time. See if that helps.

[ebrabaek]

Originally Posted by DaBit

Hmm,

I do get that orange peel texture also sometimes.



Out of 12 panels it was this bad on 1 panel and not quite as bad but visible on 2 more. The others were OK.

The 'moon surface' panel epoxy surface was cleaned with tap water, sanded with 80-grit, rinsed with deionized water and then dried with a hair dryer before applying the (tinted) epoxy. Outside temperatures were close to 30C / 85F, so no additional heat was used for curing and the panel was laid flat inside to cure. Epoxy mixed by weight and mixing ratio was spot on. No finger prints or other greasy contaminations either; I wear nitrile gloves all the time. No wax or other mold release agents were used either.

I am currently using a very fluid/low viscosity (think 'warm olive oil') epoxy system with a very long pot life (200 minutes) which also needs a post-cure for maximum strength and heat resistance. Since it is so fluid it is hard to even get bubbles in it. This does seem to worsen the orange peel compared to regular epoxies with 30-40 minutes of pot life and higher viscosity.

Strange thing: once this happens to a surface, it is almost impossible to get subsequent layers of epoxy to flow nicely. I tried wiping with acetone, rinsing with brake cleaner, wet sanding, etcetera.

For small parts it works to just clean/sand it and fill the craters with a quick-setting epoxy glue. For larger parts this is an expensive option; epoxy glue bought from the hardware store is over 16 times more expensive than epoxy resin bought in 'volume'.

I am going to try the sprayer-with-acetone method next time. See if that helps.

Most of the time is is surface tension, which can be caused by the factors I mentioned earlier. It purely could also be just a misbehaving epoxy, and sadly only way to find out, is to try another. Polymers are certainly not created equally.
I have ruled out a few other why good epoxy's over the years, because of poor surface retention. That is why I use the brand I use, as It gives me no trouble. Curious though..... Have you tried a batch with out the pigment, just to make sure that is not creating your issues????

[DaBit]

Originally Posted by ebrabaek

Most of the time is is surface tension, which can be caused by the factors I mentioned earlier.

I think I tried ruling them out although your 'forced air heating is a no-no' is definitely an eye-opener.
However, these panels were not cured by additional heat; outside temperatures were high enough (and inside even warmer. Nice choice: wearing either a T-shirt and getting the itch or covering the entire body and sweating myself to death)

It purely could also be just a misbehaving epoxy, and sadly only way to find out, is to try another. Polymers are certainly not created equally.

I use quality stuff coming from R-G composites. Datasheet of the epoxy used: http://download.r-g.de/td_de_100107.pdf. Note that it is in both German and English.

I chose this system because of the long pot life (45-60 minutes is not much when laying up more complex parts), long shelf life, low viscosity (quickly saturates fabric, excess is easily pressed outduring compression of the laminate), full cure at rtoom temperature, good mechanical properties and fairly low price per kg.

However, I had the same behaviour previously with epoxy from a local supplier (Poly-service THV500). Slightly less, but that epoxy was faster (pot life 25 minutes or so) and less fluid, which of course lessens the problem becuase the epoxy has less time to orange-peel before it starts gelling.

That is why I use the brand I use, as It gives me no trouble.

Would love to use the same brand, but US-brands are less available in Europe, and vice versa.

Curious though..... Have you tried a batch with out the pigment, just to make sure that is not creating your issues????

Not with these panels. Here I used additional layers of epoxy to smooth out the fabric texture as preparation for painting. But I have seen it happening with untinted epoxy on the luggage carriers also.

A little background: I used these panels with a glass, glass, Depron, aramid, aramid-carbon stackup for composite cases to accompany the composite luggage rack.
I am not done yet (have to make the mounting system), but here is a picture of one of the boxes in close-to-finished state:



Weight is not extremely low with 2.7kg total weight for a 30-liter pannier, but contructing them by making flat panels and glueing these together with aluminium has some construction advantages. I can use simple pressing to compact the laminate instead of a complete vacuum setup, for example. And since I do not use the cases every day I could live with the weight vs. ease of construction tradeoff.

I painted these cases black since I think a Kevlar finish is filthy, I already have enough carbon on the bike (and carbon IS expensive), and freshening up the cases is as easy as masking and rolling over another layer of paint.

I am not going to fill this topic with my own stuff, thus when interested: more pictures can be found here. Forum is Dutch, but the pictures speak a universal language I think.

[redprimo]

Originally Posted by ebrabaek

..... Curious though..... Have you tried a batch with out the pigment, just to make sure that is not creating your issues????

That was my first thought as well. It looks like you added a fair amount of pigment and even when using a compatable pigment when you aproach the maximum amount it can do some funny things. keep in mind that most systems are designed to be used in a mold and to be used with a gel coat so yor orange peel issue would never be an issue.

If you are just making flat panels I would try laying down your pigmented epoxy and letting it gel a bit then follow it with your cloth. Another option for flat panels like that is to just go with G-10. I used to have a source for G-10 scrap where it was sold by the pound and I could get just about any thickness or color and some pretty decent sizes.

[therivermonster]

Originally Posted by DaBit

Hmm,

I do get that orange peel texture also sometimes.

Out of 12 panels it was this bad on 1 panel and not quite as bad but visible on 2 more. The others were OK.

The 'moon surface' panel epoxy surface was cleaned with tap water, sanded with 80-grit, rinsed with deionized water and then dried with a hair dryer before applying the (tinted) epoxy. Outside temperatures were close to 30C / 85F, so no additional heat was used for curing and the panel was laid flat inside to cure. Epoxy mixed by weight and mixing ratio was spot on. No finger prints or other greasy contaminations either; I wear nitrile gloves all the time. No wax or other mold release agents were used either.

I am currently using a very fluid/low viscosity (think 'warm olive oil') epoxy system with a very long pot life (200 minutes) which also needs a post-cure for maximum strength and heat resistance. Since it is so fluid it is hard to even get bubbles in it. This does seem to worsen the orange peel compared to regular epoxies with 30-40 minutes of pot life and higher viscosity.

I have also read that the more fluid (low viscous) the epoxy is, the better the chances that fish eyeing will happen.
This is interesting because the epoxy that I am using is fairly thick and viscous.

Strange thing: once this happens to a surface, it is almost impossible to get subsequent layers of epoxy to flow nicely. I tried wiping with acetone, rinsing with brake cleaner, wet sanding, etcetera.

I wasn't able to get another coat to lay down very smoothly. That's not to say that it fish eyed, but it was still quite "bumpy". It sanded down nice and smooth though.

For small parts it works to just clean/sand it and fill the craters with a quick-setting epoxy glue. For larger parts this is an expensive option; epoxy glue bought from the hardware store is over 16 times more expensive than epoxy resin bought in 'volume'.

I have read that using acetone can also cause problems too. If it is used, most experts recommend wiping it on and then wiping it off with a clean paper towel while it is still wet. This will remove the contaminants that the solvent is supposed to clean up.

I am going to try the sprayer-with-acetone method next time. See if that helps.

Dabit, your panniers look very nice BTW.

Originally Posted by ebrabaek

Most of the time is is surface tension, which can be caused by the factors I mentioned earlier. It purely could also be just a misbehaving epoxy, and sadly only way to find out, is to try another. Polymers are certainly not created equally.
I have ruled out a few other why good epoxy's over the years, because of poor surface retention. That is why I use the brand I use, as It gives me no trouble. Curious though..... Have you tried a batch with out the pigment, just to make sure that is not creating your issues????

[therivermonster]

Originally Posted by redprimo

That was my first thought as well. It looks like you added a fair amount of pigment and even when using a compatable pigment when you aproach the maximum amount it can do some funny things. keep in mind that most systems are designed to be used in a mold and to be used with a gel coat so yor orange peel issue would never be an issue.

If you are just making flat panels I would try laying down your pigmented epoxy and letting it gel a bit then follow it with your cloth. Another option for flat panels like that is to just go with G-10. I used to have a source for G-10 scrap where it was sold by the pound and I could get just about any thickness or color and some pretty decent sizes.

Flat Panel Layup Technique...
I have read that you can also get really nice results by applying mold release to two glass pains, lay down a nice coat of epoxy on one of the pains, lay your fabric, lay down the other glass pain on top of the wet fabric, then apply weight to the top glass pain.
Apparently this yields a nice, smooth panel.

[zoomzu]

Originally Posted by therivermonster

Flat Panel Layup Technique...
I have read that you can also get really nice results by applying mold release to two glass pains, lay down a nice coat of epoxy on one of the pains, lay your fabric, lay down the other glass pain on top of the wet fabric, then apply weight to the top glass pain.
Apparently this yields a nice, smooth panel.

That gives me ideas on some hard panniers.

[100mpg]

Originally Posted by dabit

i am not going to fill this topic with my own stuff, thus when interested: More pictures can be found here. Forum is dutch, but the pictures speak a universal language i think.

pm sent!!!

[DaBit]

Originally Posted by redprimo

That was my first thought as well. It looks like you added a fair amount of pigment and even when using a compatable pigment when you aproach the maximum amount it can do some funny things.

It is a pigment made to dye polyester, vinylester and epoxy resins. But what is the maximum amount? The datasheet doesn't say much more than 'add as much as is needed'. It is also a very strong pigment; two drops in a batch of 100 grams epoxy yields black paint.

keep in mind that most systems are designed to be used in a mold and to be used with a gel coat so yor orange peel issue would never be an issue.

True. But then I would say that it would always suffers from orange peel. Not 9 panels no, 3 panels yes.

If you are just making flat panels I would try laying down your pigmented epoxy and letting it gel a bit then follow it with your cloth.

I used the bare, clear epoxy to make the flat panels. Later on I used a dyed epoxy to smooth out the 'wavy' surface of the cloth. I dyed it so a scratch in the paint won't immediately reveal the yellow aramid.

Another option for flat panels like that is to just go with G-10. I used to have a source for G-10 scrap where it was sold by the pound and I could get just about any thickness or color and some pretty decent sizes.

G-10 is just like FR-4 printed circuit board laminate, right? I use that every day
Certainly strong, but heavy also.

The side panels consist of 2 layers of glass fabric (0,5mm thickness or so), then a 3mm Depron core, and then a layer of aramid and a layer of aramid/carbon hybrid. Aramid/carbon only because that's what I had on the shelf. Total thickness around 4mm.
The bottom panel, which bears more load, has 2 Depron cores, a layer of carbon/aramid between the cores, and several holes filled with epoxy/glass to tightly interconnect the fabric layers.
The backsidepanel where the mounting resides has a 4mm plywood core instead of Depron. Heavier but far more resistant to concentrated stress around the mounting points and pressure.

The aramid on the outside provides tearing resistance, the very lightweight core increases outside dimensions which provides stiffness. The glass/depron/aramid panels weight almost nothing (45x20cm panel weights somewhat less than 80 grams), but they are pretty stiff and strong. Especially when mounted in the aluminium angle 'frame'.

Truly a composite construction made of glass, aramid, carbon, epoxy, expanded polystyrene, wood, aluminium and steel

I have also read that the more fluid (low viscous) the epoxy is, the better the chances that fish eyeing will happen.
This is interesting because the epoxy that I am using is fairly thick and viscous.

Besides the fisheyeing I am pretty happy with the system. Long pot life is a blessing since it usually takes quite some time to lay up and saturate all the fabric for a part, and then the epoxy must still be fluid enough to press out the excess into the absorber mat when pressurizing the laminate. I have a hard time doing that in 40-60 minutes, except for a flat panel or so. The low viscosity saturates fabric quickly without bubbles or air pockets, and makes it hard to use far too much resin to begin with.

BTW: it is easy to thicken the resin, even up to peanut butter consistency. Did that for the 'glue' I used to assemble the panels into a box. It will lose it's transparency and become milky though when adding thickener, so not suitable for bare carbon finishes. But it is what I probably should have done for these panels. Thicken epoxy, apply, sand smooth.

I have read that using acetone can also cause problems too. If it is used, most experts recommend wiping it on and then wiping it off with a clean paper towel while it is still wet. This will remove the contaminants that the solvent is supposed to clean up.

Normally I use water only. The surface is not contaminated anyway since it is freshly cured epoxy which nobody touched with bare fingers. So all I have to deal with is possibly amine blush (which can be removed with water) and a little dust.
But if water doesn't work we all grab whatever chemical is within reach, right?

Dabit, your panniers look very nice BTW.

Thanks!
Will put a full post on them (and the composite luggage carrier) in OC when done.

Flat Panel Layup Technique...
I have read that you can also get really nice results by applying mold release to two glass pains, lay down a nice coat of epoxy on one of the pains, lay your fabric, lay down the other glass pain on top of the wet fabric, then apply weight to the top glass pain.

I used layers of fairly thick polyethylene foil between the panels and sheets of PE on top/bottom. Epoxy doesn't stick well to PE, so no mold release is required.

I did press by stacking the panels and applying weight and C-clamps. But mind you, if you are after maximum strength, you need a LOT of pressure. Even for modest surface areas. This is the beauty of vacuum; 6-10 tons per square meter of pressure. Almost 15 pounds per square inch. And a square inch is not very much. 15 pounds on that little amount of area is, ehm, pretty much.

With this in mind: needless to say that my panel laminate is only around 40% fiber or so. Can't calculate accurately because I did not weigh the Depron in advance. But for this purpose, who cares?

[therivermonster]

The mini fairing layup popped off the plug with no trouble. Notice the PVA film on the inside of the part...


It looks good. Feels strong...


I can see how laying up in a female mold could give a very nice finish. The inside is much nicer then the outside, but it still has its problmes. Bubbles...


You can see the inside finish a little better here.


Here they are - the plug and the part. I spent a fair amount of time on that plug. Probably too much.


I trimmed the fairing up a little bit, including a fair amount of the lower part. I like the looks better this way.
I used these cutters in my Dremel from Harbor Freight Tools. They are super cheap and work very well.


Because I layed the fabric on the outside of the plug/mold, the surface finish on the outside of the part is fairly rough with the fabric printing through. Nothing a little sanding won't help.
I didn't forget the beer this time.


I sanded with 60 grit, then 220 grit to get to what you see here. It's much smoother, but doesn't look all that good.


Seeing as this is an experimental piece, I decided to get a little creative with it. Stripes!!!


Sexy. But the cf is still a bit dull.


So I put another thin layer of epoxy down and all is well.
It could look better, but I'm calling it done on this part.


We went from some pieces of foam board, to a plug, to a part. Thats the name of the game, friends!!




Thanks every one for tagging along. Now on with the next project... a muffler shroud for the DR.

[JimVonBaden]

I think it looks fantastic!

Can you show us on the bike how it will look?

Jim

[therivermonster]

Project #2: DR 650 Exhaust Shroud

I pulled the exhaust shroud off the DR today to prep it to make a clone out of carbon fiber. I'll make a proper mold for this part.

We'll be making a copy of the shroud pictured here. Notice I have already removed the screws in order to remove the shroud.


I hot glued the shroud to a piece of plywood. The shroud will stay glued to the plywood through the process of creating the mold.


After sanding the aluminum shroud, I shot it with a coat of high build primer.


Then I used some Bondo to fill the small gap between the edge of the part and the plywood.


Then another coat of primer.


That's all I had time for tonight, but I'll post updates as the project progresses.

This is fun stuff!!

[therivermonster]

Originally Posted by JimVonBaden

I think it looks fantastic!

Can you show us on the bike how it will look?

Jim

Is that a joke, Jim?

The fairing is far to small to work on the bike. It's just a little model. More of a proof of concept really.

The real deal fairing project will come in the future.

[JimVonBaden]

Originally Posted by therivermonster

Is that a joke, Jim?

The fairing is far to small to work on the bike. It's just a little model. More of a proof of concept really.

The real deal fairing project will come in the future.

No, I didn't catch that it wasn't full size! However, it still looks fantastic!

I can see a couple uses for it right now. A sconce in the den or garage, first comes to mind.

Jim